CVE-2016-3069 in Mercurial
Summary
by MITRE
Mercurial before 3.7.3 allows remote attackers to execute arbitrary code via a crafted name when converting a Git repository.
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Analysis
by VulDB Data Team • 07/24/2022
The vulnerability identified as CVE-2016-3069 represents a critical remote code execution flaw within the Mercurial distributed version control system. This vulnerability specifically affects Mercurial versions prior to 3.7.3 and stems from inadequate input validation during the conversion process of Git repositories. The flaw occurs when Mercurial processes a crafted name parameter during repository conversion operations, creating a pathway for malicious actors to inject and execute arbitrary code on the target system.
The technical implementation of this vulnerability resides in the Git repository conversion functionality where Mercurial fails to properly sanitize or validate user-supplied names that are used in the conversion process. When a remote attacker crafts a malicious name containing specially formatted input, the system processes this data without adequate protection mechanisms, leading to code execution with the privileges of the Mercurial process. This represents a classic command injection vulnerability where user-controllable data is directly incorporated into system commands without proper sanitization or escaping.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with complete control over systems running vulnerable Mercurial installations. An attacker could leverage this vulnerability to install backdoors, exfiltrate sensitive data, modify repository contents, or establish persistent access to the affected system. The remote nature of the attack means that exploitation can occur without requiring physical access to the target system, making it particularly dangerous for organizations that maintain public repositories or use Mercurial in networked environments. This vulnerability directly aligns with CWE-78, which describes improper neutralization of special elements used in OS commands, and maps to ATT&CK technique T1059.001 for command and script injection.
Organizations should immediately upgrade to Mercurial version 3.7.3 or later to mitigate this vulnerability, as this release includes proper input validation and sanitization measures for the Git conversion process. Additional mitigations include implementing network segmentation to limit access to Mercurial servers, restricting repository conversion operations to trusted users only, and monitoring for unusual repository conversion activities. Security administrators should also consider implementing application whitelisting policies that restrict the execution of untrusted code during repository operations. The vulnerability demonstrates the critical importance of input validation in distributed systems and highlights the need for comprehensive security testing of conversion and import functionalities within version control systems.