CVE-2017-12426 in Community Edition
Summary
by MITRE
GitLab Community Edition (CE) and Enterprise Edition (EE) before 8.17.8, 9.0.x before 9.0.13, 9.1.x before 9.1.10, 9.2.x before 9.2.10, 9.3.x before 9.3.10, and 9.4.x before 9.4.4 might allow remote attackers to execute arbitrary code via a crafted SSH URL in a project import.
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Analysis
by VulDB Data Team • 11/06/2019
This vulnerability affects GitLab Community Edition and Enterprise Edition versions prior to specific patch releases, creating a critical remote code execution risk through maliciously crafted SSH URLs during project import operations. The flaw resides in how GitLab processes and validates SSH URLs when importing projects, allowing attackers to inject malicious commands that execute with the privileges of the GitLab server process. The vulnerability specifically impacts versions across multiple release branches including 8.17.x, 9.0.x, 9.1.x, 9.2.x, 9.3.x, and 9.4.x before their respective patch levels. This represents a significant security gap that could enable attackers to gain complete control over GitLab installations, potentially leading to data breaches, system compromise, and unauthorized access to source code repositories. The issue stems from inadequate input sanitization and command execution handling within the project import functionality.
The technical implementation of this vulnerability involves the improper handling of SSH URLs during the project import process, where user-supplied URLs are not properly validated or escaped before being used in system commands. When GitLab processes an import request with a crafted SSH URL, the system executes shell commands without sufficient sanitization, allowing attackers to inject arbitrary commands that get executed on the server. This type of vulnerability maps directly to CWE-78, which describes improper neutralization of special elements used in OS commands, and also aligns with CWE-20, representing input validation issues that enable command injection attacks. The attack vector leverages the trust model where GitLab accepts user-provided URLs without adequate security checks, creating a pathway for malicious code execution. This vulnerability is particularly dangerous because it operates at the system level, executing commands with the privileges of the GitLab service account which typically has broad access to the server's file system and network resources.
The operational impact of this vulnerability extends beyond simple code execution to encompass complete system compromise and potential data exfiltration. Attackers could leverage this vulnerability to install backdoors, modify or delete source code repositories, access confidential information stored in GitLab, and potentially use the compromised system as a launching point for further attacks within the network. The vulnerability affects organizations that rely on GitLab for source code management, as a successful exploitation could result in intellectual property theft, regulatory compliance violations, and significant business disruption. Organizations with multiple GitLab instances or those using automated import processes would be particularly vulnerable, as the attack could be executed programmatically without requiring user interaction. This vulnerability also impacts the integrity of GitLab's security model, as it allows attackers to bypass the normal access controls and execute arbitrary operations within the GitLab environment. The attack could be particularly devastating in continuous integration environments where GitLab is used for automated builds and deployments.
Organizations should immediately upgrade to the patched versions of GitLab, specifically versions 8.17.8, 9.0.13, 9.1.10, 9.2.10, 9.3.10, and 9.4.4 respectively, to mitigate this risk. Additionally, administrators should implement network-level restrictions to prevent unauthorized access to GitLab import functionality, particularly in environments where untrusted users have access to the system. The mitigation strategy should include monitoring for suspicious import activities and implementing strict input validation for all URL parameters. Security teams should also consider implementing web application firewalls to detect and block malicious URL patterns, as well as conducting regular security assessments to identify similar vulnerabilities in other components of the GitLab installation. The vulnerability highlights the importance of secure coding practices, particularly in handling user input within system commands, and demonstrates the critical need for regular security updates and vulnerability management processes. This issue also reinforces the necessity of following security best practices such as the principle of least privilege and input validation, which are fundamental to preventing command injection attacks and maintaining overall system security posture.