CVE-2022-21187 in libvcs
Summary
by MITRE • 03/14/2022
The package libvcs before 0.11.1 are vulnerable to Command Injection via argument injection. When calling the update_repo function (when using hg), the url parameter is passed to the hg clone command. By injecting some hg options it was possible to get arbitrary command execution.
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Analysis
by VulDB Data Team • 03/16/2022
The vulnerability identified as CVE-2022-21187 affects the libvcs library versions prior to 0111, representing a critical command injection flaw that enables arbitrary code execution through argument injection. This security weakness specifically manifests within the update_repo function when utilizing the mercurial (hg) version control system. The vulnerability stems from improper input validation and sanitization of the url parameter that gets directly passed to the hg clone command without adequate protection mechanisms. Attackers can exploit this by injecting malicious hg command options into the url parameter, effectively bypassing normal execution boundaries and gaining unauthorized access to the underlying system.
The technical exploitation of this vulnerability follows a well-established pattern of command injection attacks where user-supplied input is concatenated directly into system commands without proper sanitization. When the update_repo function processes a repository URL containing malicious hg options, these options get interpreted by the hg command parser as actual command parameters rather than simple URL components. This allows attackers to inject additional commands that execute with the privileges of the process running libvcs, potentially leading to complete system compromise. The vulnerability is particularly dangerous because it leverages legitimate system commands while appearing to be normal repository operations, making detection more challenging for security monitoring systems.
From an operational perspective, this vulnerability poses significant risks to organizations that rely on libvcs for automated repository management and version control operations. The impact extends beyond simple code execution to include potential data exfiltration, system persistence mechanisms, and privilege escalation opportunities. Attackers could leverage this vulnerability to gain unauthorized access to source code repositories, modify critical system files, or establish backdoors within the affected environment. The attack surface is particularly broad given that libvcs is commonly used in continuous integration pipelines, automated deployment systems, and various DevOps toolchains where repository operations are frequently automated and may run with elevated privileges.
The vulnerability maps directly to CWE-78, which specifically addresses OS Command Injection, and aligns with several tactics in the MITRE ATT&CK framework including T1059.001 for command and scripting interpreter and T1068 for exploit for privilege escalation. Organizations should immediately implement mitigations including upgrading to libvcs version 0.11.1 or later, implementing strict input validation and sanitization for all repository URLs, and employing principle of least privilege for processes that execute repository operations. Additional protective measures include monitoring for suspicious command execution patterns, implementing network segmentation, and conducting regular security assessments of automated systems that interact with version control repositories. The fix for this vulnerability involves proper input sanitization and parameter escaping to prevent malicious options from being interpreted as command parameters by the underlying hg command execution layer.