CVE-2017-0917 in Community Edition
Summary
by MITRE
Gitlab Community Edition version 10.2.4 is vulnerable to lack of input validation in the CI job component resulting in persistent cross site scripting.
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Analysis
by VulDB Data Team • 01/15/2020
The vulnerability identified as CVE-2017-0917 affects Gitlab Community Edition version 10.2.4 and represents a critical security flaw in the continuous integration job component. This issue stems from inadequate input validation mechanisms that fail to properly sanitize user-supplied data within the CI job processing pipeline. The flaw allows malicious actors to inject persistent cross-site scripting payloads that can execute in the context of other users' browsers when they view affected CI job pages. The vulnerability operates at the application layer and specifically targets the web interface components responsible for displaying CI job information, making it particularly dangerous in collaborative development environments where multiple users interact with shared CI systems. The lack of proper input sanitization creates an attack surface that can be exploited by unauthorized individuals to gain unauthorized access to sensitive information or compromise user sessions.
The technical implementation of this vulnerability resides in the CI job processing logic where user-provided data is not adequately filtered or escaped before being rendered in web pages. When a user creates or modifies a CI job configuration, the system fails to validate the input parameters, particularly those related to job names, descriptions, or other configurable fields that may contain user-controllable content. This validation gap allows attackers to inject malicious javascript code or other script payloads that persist in the system and execute whenever legitimate users access the affected CI job interfaces. The vulnerability aligns with CWE-79 which describes cross-site scripting flaws, and more specifically with CWE-20 which addresses insufficient input validation. The flaw demonstrates a classic persistent XSS vulnerability where the malicious code is stored on the server and executed against multiple users who view the affected content, making it particularly dangerous in shared development environments.
The operational impact of CVE-2017-0917 extends beyond simple data theft or session hijacking, as it can enable sophisticated attack chains that leverage the compromised CI environment. An attacker who successfully exploits this vulnerability can potentially access sensitive build artifacts, credentials stored in CI job configurations, or even escalate privileges within the Gitlab system. The persistent nature of the vulnerability means that once exploited, the malicious payloads remain active until manually removed, providing attackers with sustained access to the compromised system. This vulnerability is particularly concerning in enterprise environments where Gitlab serves as a central hub for development workflows, as it can compromise the integrity of the entire CI/CD pipeline and potentially provide attackers with access to production systems. The vulnerability can be exploited through the ATT&CK technique T1059.007 which involves command and scripting interpreter usage, specifically targeting web applications through XSS vectors. Organizations using vulnerable Gitlab versions may experience unauthorized access to source code repositories, build artifacts, and sensitive configuration data that could lead to further system compromise.
Mitigation strategies for CVE-2017-0917 should prioritize immediate remediation through official Gitlab security updates and patches. Organizations must upgrade to Gitlab versions that address this vulnerability, specifically versions released after the patch date for CVE-2017-0917. Additionally, implementing proper input validation and output encoding mechanisms within the CI job processing components can provide defense-in-depth measures. Security teams should consider implementing web application firewalls to detect and block suspicious payloads, while also conducting regular security audits of CI job configurations to identify potential injection points. The implementation of content security policies can provide additional protection against script execution, and regular security training for developers can help prevent the introduction of similar vulnerabilities in custom CI configurations. Organizations should also establish monitoring procedures to detect anomalous behavior in CI job processing and implement proper access controls to limit who can modify CI job configurations, thereby reducing the attack surface available to potential adversaries.