CVE-2016-3105 in Mercurial
Summary
by MITRE
The convert extension in Mercurial before 3.8 might allow context-dependent attackers to execute arbitrary code via a crafted git repository name.
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Analysis
by VulDB Data Team • 10/09/2024
The vulnerability identified as CVE-2016-3105 resides within the convert extension of Mercurial version 3.8 and earlier, representing a critical security flaw that enables context-dependent attackers to execute arbitrary code through manipulation of git repository names. This issue stems from insufficient input validation and sanitization within the conversion process that occurs when Mercurial handles git repositories. The convert extension serves as a bridge between different version control systems, facilitating migration and conversion between formats including git, svn, and others. When processing a crafted git repository name, the system fails to properly validate or escape special characters that could be interpreted as shell commands or file system directives, creating a potential attack vector for remote code execution.
The technical nature of this vulnerability aligns with CWE-78, which describes improper neutralization of special elements used in shell commands, and CWE-20, which addresses input validation issues. The flaw operates through a command injection mechanism where maliciously crafted repository names containing shell metacharacters can be passed directly to underlying shell commands without proper sanitization. This occurs specifically during the conversion process when Mercurial attempts to parse and process git repository metadata, particularly when handling repository names that contain special characters such as semicolons, pipes, or backticks that could be interpreted by the shell. The vulnerability is context-dependent because it requires an attacker to have the ability to influence the repository name being processed, typically through a malicious git repository or by manipulating the conversion workflow in a specific environment.
The operational impact of this vulnerability extends beyond simple code execution, potentially allowing attackers to gain full control over systems running vulnerable versions of Mercurial. Attackers could leverage this flaw to execute arbitrary commands with the privileges of the user running Mercurial, which could include system administrators or developers who regularly use the convert extension. The implications are particularly severe in environments where Mercurial is used for automated workflows, continuous integration systems, or when developers import external repositories. The vulnerability could be exploited through various attack vectors including malicious repository imports, supply chain attacks, or by compromising repositories that are subsequently converted. Organizations using Mercurial for version control, especially those with automated build processes or repository import workflows, face significant risk if they operate vulnerable versions of the software.
Mitigation strategies for CVE-2016-3105 primarily involve upgrading to Mercurial version 3.8 or later, where the vulnerability has been addressed through proper input validation and sanitization of repository names during the conversion process. System administrators should implement comprehensive patch management procedures to ensure all Mercurial installations are updated promptly. Additional defensive measures include restricting repository import privileges to trusted users only, implementing network segmentation to limit access to version control systems, and conducting regular security audits of version control workflows. Organizations should also consider implementing automated scanning tools that can detect and prevent the use of potentially malicious repository names in conversion processes. The fix implemented in Mercurial 3.8 specifically addresses the command injection vulnerability by properly escaping special characters in repository names and ensuring that user-provided input is validated before being passed to shell commands, aligning with ATT&CK technique T1059.001 for command and scripting interpreter execution. Security teams should also monitor for any potential workarounds or similar vulnerabilities in related software components and maintain updated threat intelligence regarding version control system security issues.