CVE-2010-2956 in sudo
Summary
by MITRE
Sudo 1.7.0 through 1.7.4p3, when a Runas group is configured, does not properly handle use of the -u option in conjunction with the -g option, which allows local users to gain privileges via a command line containing a "-u root" sequence.
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Analysis
by VulDB Data Team • 09/24/2021
The vulnerability described in CVE-2010-2956 affects the sudo command utility version 1.7.0 through 1.7.4p3, specifically when a Runas group configuration is in place. This represents a critical privilege escalation flaw that undermines the security model of the sudo command. The issue stems from improper handling of command line arguments when both the -u (user) and -g (group) options are used simultaneously, creating a scenario where local attackers can bypass intended access controls and elevate their privileges to root level access.
The technical flaw manifests in the sudo command's argument parsing mechanism where the presence of a "-u root" sequence in a command line that also includes the -g option causes the system to incorrectly process the user specification. This occurs because the sudo utility fails to properly validate or sanitize the combination of these command line arguments when runas groups are configured. The vulnerability specifically exploits a race condition or parsing error in how sudo interprets the order and interaction of these parameters, allowing an attacker to inject malicious user specifications that override the intended group-based access controls.
From an operational perspective, this vulnerability presents a significant risk to systems relying on sudo for privilege management. Local users who can execute commands through sudo with runas group configurations can exploit this flaw to gain root access without proper authentication or authorization. The impact extends beyond simple privilege escalation as it can enable attackers to modify system files, install malware, or establish persistent backdoors. The vulnerability is particularly dangerous in multi-user environments where sudo is commonly used to provide limited administrative access to specific users or groups.
The flaw aligns with CWE-284 (Improper Access Control) and CWE-250 (Execute with Unnecessary Privileges) categories, demonstrating how improper argument handling can lead to unauthorized privilege elevation. From an ATT&CK framework perspective, this vulnerability maps to T1068 (Local Privilege Escalation) and T1548.003 (Evasion: Uncommonly Used Port) as attackers may leverage this to establish persistent access. The vulnerability also relates to T1078 (Valid Accounts) and T1562.001 (Impair Defenses: Disable or Modify Tools) as it allows attackers to bypass security controls that should prevent unauthorized root access.
Mitigation strategies for CVE-2010-2956 require immediate patching of affected sudo versions to 1.7.4p4 or later, which contains the necessary fixes for proper argument handling. Organizations should also review sudo configuration files to minimize the use of runas groups where possible, and implement strict access controls through sudoers configuration. Additional security measures include monitoring sudo command execution logs for suspicious patterns, particularly sequences involving -u and -g options, and implementing privileged access management solutions. Regular security audits of sudo configurations should be conducted to identify and remediate similar vulnerabilities in other system utilities and applications.