CVE-2018-20683 in gitolite
Summary
by MITRE
commands/rsync in Gitolite before 3.6.11, if .gitolite.rc enables rsync, mishandles the rsync command line, which allows attackers to have a "bad" impact by triggering use of an option other than -v, -n, -q, or -P.
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Analysis
by VulDB Data Team • 06/26/2023
Gitolite represents a widely adopted access control system for git repositories that provides fine-grained permissions management and automated repository creation capabilities. The vulnerability CVE-2018-20683 specifically targets the rsync command handling mechanism within Gitolite versions prior to 3.6.11. This flaw exists in the configuration parsing logic that processes the .gitolite.rc file when rsync functionality is enabled. The vulnerability stems from insufficient input validation and sanitization of command line arguments passed to the rsync utility, creating a potential vector for privilege escalation and unauthorized system access.
The technical implementation of this vulnerability occurs within the commands/rsync module where Gitolite fails to properly validate or sanitize command line parameters before executing rsync operations. When rsync is enabled through the .gitolite.rc configuration file, the system accepts user-provided parameters without adequate filtering or restriction. This allows attackers to inject malicious rsync options that were not intended to be available to regular users. The vulnerability specifically permits the use of rsync options beyond the restricted set of -v, -n, -q, and -P, which could include dangerous flags such as --delete, --chmod, or --exec that could lead to unauthorized file deletion, permission changes, or arbitrary command execution on the target system.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass potential data integrity compromise and system availability threats. Attackers could exploit this flaw to manipulate repository contents, delete sensitive files, or execute arbitrary commands with the privileges of the Gitolite user. This represents a critical security weakness in the access control mechanism that could allow unauthorized users to gain elevated privileges and potentially compromise the entire git infrastructure. The vulnerability aligns with CWE-78, which addresses improper neutralization of special elements used in OS commands, and also corresponds to ATT&CK technique T1059 for executing malicious commands through command-line interfaces.
Mitigation strategies for this vulnerability require immediate patching of Gitolite installations to version 3.6.11 or later where the command line argument sanitization has been properly implemented. Organizations should also review their .gitolite.rc configuration files to ensure rsync functionality is disabled unless absolutely required for specific use cases. Additional security measures include implementing strict input validation at multiple layers, monitoring for unauthorized rsync usage patterns, and conducting regular security audits of access control configurations. System administrators should also consider implementing network segmentation and privilege separation to limit the potential impact of successful exploitation attempts. The vulnerability demonstrates the importance of proper input validation in security-critical components and highlights the need for comprehensive testing of command execution paths in access control systems.