CVE-2017-8386 in Git
Summary
by MITRE
git-shell in git before 2.4.12, 2.5.x before 2.5.6, 2.6.x before 2.6.7, 2.7.x before 2.7.5, 2.8.x before 2.8.5, 2.9.x before 2.9.4, 2.10.x before 2.10.3, 2.11.x before 2.11.2, and 2.12.x before 2.12.3 might allow remote authenticated users to gain privileges via a repository name that starts with a - (dash) character.
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Analysis
by VulDB Data Team • 12/06/2022
The vulnerability identified as CVE-2017-8386 affects git-shell functionality across multiple versions of the git software suite, specifically impacting versions prior to the mentioned security patches. This flaw represents a significant privilege escalation risk that could be exploited by authenticated remote attackers who possess repository access rights. The vulnerability stems from insufficient input validation within the git-shell component, which processes repository names during git operations. When a repository name begins with a dash character, the system fails to properly sanitize this input, creating a potential attack vector that could be leveraged to execute arbitrary commands with elevated privileges.
The technical root cause of this vulnerability lies in the improper handling of command-line arguments within git-shell's parsing mechanism. This issue aligns with CWE-20, which describes improper input validation, and more specifically with CWE-78, which addresses OS command injection vulnerabilities. The flaw occurs because git-shell treats repository names as command-line arguments without adequate sanitization, allowing attackers to craft malicious repository names that could be interpreted as command options rather than repository identifiers. When the system processes a repository name starting with a dash, these characters can be interpreted by the underlying shell as command-line switches, potentially enabling attackers to inject malicious commands into the execution flow.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass potential full system compromise when the affected git-shell is used in conjunction with user accounts that have elevated permissions. Attackers could exploit this weakness to execute arbitrary commands on the system hosting the git repository, potentially leading to unauthorized data access, modification, or deletion. The vulnerability affects various git server implementations including those used in enterprise environments, development workflows, and continuous integration systems where git-shell is commonly deployed. Organizations utilizing git for version control in environments where user authentication is required are particularly at risk, as the attack requires only authenticated access to a repository rather than administrative privileges.
Mitigation strategies for CVE-2017-8386 focus primarily on upgrading to patched versions of git software as specified in the vulnerability advisory. System administrators should immediately update all git installations to versions 2.4.12, 2.5.6, 2.6.7, 2.7.5, 2.8.5, 2.9.4, 2.10.3, 2.11.2, or 2.12.3, depending on their current git version. Additionally, organizations should implement repository name validation policies that prevent the creation of repositories with names beginning with special characters, particularly the dash character. Security monitoring should include detection of unusual repository naming patterns and command execution logs that might indicate exploitation attempts. This vulnerability also highlights the importance of following the principle of least privilege in git server configurations, ensuring that user accounts have minimal necessary permissions and that repository access controls are properly enforced. The ATT&CK framework categorizes this type of vulnerability under T1059 for command and script injection techniques, emphasizing the need for robust input validation and secure coding practices in shell-based applications.