CVE-2013-6876 in s3dvt
Summary
by MITRE
The (1) pty_init_terminal and (2) pipe_init_terminal functions in main.c in s3dvt 0.2.2 and earlier allows local users to gain privileges by leveraging setuid permissions and usage of bash 4.3 and earlier. NOTE: this vulnerability was fixed with commit ad732f00b411b092c66a04c359da0f16ec3b387, but the version number was not changed.
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Analysis
by VulDB Data Team • 02/27/2023
The vulnerability identified as CVE-2013-6876 represents a privilege escalation flaw in the s3dvt utility version 0.2.2 and earlier, specifically affecting the pty_init_terminal and pipe_init_terminal functions within the main.c source file. This vulnerability exploits the inherent security risks associated with setuid binaries and the shell execution environment, creating a pathway for local attackers to elevate their privileges from standard user level to root access. The flaw manifests when these functions execute shell commands without proper sanitization of environment variables, particularly the PATH variable, which can be manipulated by unprivileged users to inject malicious code.
The technical root cause of this vulnerability stems from improper handling of shell command execution within privileged contexts. When the s3dvt utility runs with setuid permissions, it inherits elevated privileges but fails to properly isolate the execution environment of shell commands. The functions in question utilize bash 4.3 and earlier versions where environment variable handling is vulnerable to path manipulation attacks. This creates a condition where an attacker can modify the PATH environment variable to point to a maliciously crafted version of a command that would normally be executed by the privileged process, effectively allowing arbitrary code execution with elevated privileges.
From an operational perspective, this vulnerability presents a significant risk to systems running affected versions of s3dvt, as it transforms a local user account into a root-level attacker. The attack requires only local access to the system and does not need network connectivity, making it particularly dangerous in multi-user environments where privilege separation is critical. The vulnerability aligns with CWE-78 Improper Neutralization of Special Elements used in an OS Command, which specifically addresses the improper handling of shell metacharacters and environment variables in command execution contexts. This weakness enables attackers to bypass normal access controls and escalate privileges through a well-known attack vector that has been documented in numerous security advisories.
The impact of this vulnerability extends beyond simple privilege escalation as it can be leveraged to establish persistent access to systems, modify critical system files, and potentially compromise the entire security posture of affected environments. The fix implemented through commit ad732f00b411b092c66a04c359da0f16ec3b387 demonstrates the importance of proper environment variable sanitization in privileged code execution contexts. This vulnerability also maps to ATT&CK technique T1068, which describes the use of local privilege escalation techniques, and T1548.003, which covers abuse of sudo or setuid binaries for privilege escalation purposes. Organizations should prioritize patching this vulnerability as it represents a classic example of how insecure coding practices in setuid programs can create persistent backdoors for attackers. The vulnerability underscores the critical importance of following secure coding practices, particularly in privileged code paths, and demonstrates the necessity of maintaining current software versions to protect against known security flaws that have been addressed in subsequent releases.