CVE-2017-0927 in Community Edition
Summary
by MITRE
Gitlab Community Edition version 10.3 is vulnerable to an improper authorization issue in the deployment keys component resulting in unauthorized use of deployment keys by guest users.
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Analysis
by VulDB Data Team • 02/22/2023
The vulnerability identified as CVE-2017-0927 affects Gitlab Community Edition version 10.3 and represents a critical authorization flaw within the deployment keys component. This issue allows guest users to exploit improper access controls and gain unauthorized usage of deployment keys that should be restricted to authorized personnel only. The vulnerability stems from insufficient validation mechanisms that fail to properly verify user permissions when accessing deployment key resources, creating a pathway for unauthorized individuals to leverage these keys for system access. The flaw specifically impacts the authorization logic that governs who can view, use, or manage deployment keys within project environments, fundamentally undermining the security model that separates different user roles and their corresponding access levels.
The technical implementation of this vulnerability resides in the improper enforcement of access control policies within Gitlab's deployment keys functionality. When guest users attempt to access deployment keys associated with projects, the system fails to adequately validate their authorization level, allowing these users to bypass normal access restrictions. This authorization bypass occurs due to flawed permission checking mechanisms that do not properly distinguish between different user roles, particularly failing to recognize that guest users should not have access to deployment keys. The vulnerability is classified under CWE-285, which addresses improper authorization within software systems, and aligns with ATT&CK technique T1078.101 which covers valid accounts with restricted permissions being used to access systems. The flaw manifests when the application processes requests for deployment key information without performing adequate role-based access control checks, enabling guest users to obtain sensitive deployment key data.
The operational impact of this vulnerability extends beyond simple unauthorized access to potentially compromising entire deployment pipelines and system security. Guest users who exploit this vulnerability can gain access to deployment keys that may grant them read or write access to production environments, potentially allowing them to deploy malicious code, modify application configurations, or access sensitive data. The implications are particularly severe for organizations that rely on deployment keys for automated deployments, as unauthorized access could lead to complete system compromise or data breaches. This vulnerability essentially allows low-privilege users to escalate their access level through the deployment key mechanism, creating a significant security risk that could result in unauthorized system modifications, data exfiltration, or service disruption. Organizations using Gitlab with guest user access may experience unauthorized access to production environments, potentially leading to compliance violations and security incidents.
Mitigation strategies for CVE-2017-0927 should prioritize immediate patching of Gitlab Community Edition to version 10.4 or later, which contains the necessary fixes for the authorization issue. Organizations should also implement additional monitoring controls to detect unauthorized access attempts to deployment keys and establish strict access control policies that limit guest user privileges. Security teams should conduct comprehensive audits of deployment key usage and permissions to identify any potential exploitation that may have already occurred. The fix implemented by Gitlab addresses the root cause by strengthening the authorization checks within the deployment keys component, ensuring that guest users cannot access deployment key information regardless of their project membership status. Organizations should also consider implementing network-level controls and access logging to prevent similar issues from occurring in other systems that may have similar authorization flaws. Regular security assessments of authentication and authorization mechanisms should be conducted to identify and remediate similar vulnerabilities before they can be exploited by malicious actors.