CVE-2024-3035 in Community Edition
Summary
by MITRE • 08/08/2024
A permission check vulnerability in GitLab CE/EE affecting all versions starting from 8.12 prior to 17.0.6, 17.1 prior to 17.1.4, and 17.2 prior to 17.2.2 allowed for LFS tokens to read and write to the user owned repositories.
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Analysis
by VulDB Data Team • 08/29/2024
This vulnerability represents a critical permission bypass flaw in GitLab's Large File Storage (LFS) implementation that has persisted across multiple version ranges from 8.12 through 17.2. The issue stems from inadequate access control mechanisms that fail to properly validate user permissions when processing LFS token requests. Specifically, the vulnerability allows authenticated users to leverage their LFS tokens to perform read and write operations on repositories they own, despite the system's intended access controls that should restrict such actions. This represents a direct violation of the principle of least privilege and undermines the core security model that separates user permissions from repository access controls. The flaw is particularly concerning because it operates at the intersection of authentication and authorization mechanisms, where the LFS token authentication process fails to properly verify that the requesting user possesses the appropriate permissions for the target repository.
The technical implementation of this vulnerability demonstrates a classic access control weakness that aligns with CWE-285, which addresses improper authorization within software systems. The vulnerability occurs when GitLab processes LFS token requests and fails to validate that the token holder has legitimate access to the repository in question. This misconfiguration allows attackers to escalate their privileges through legitimate LFS token usage, effectively bypassing repository-level access controls that should normally prevent unauthorized access to user-owned repositories. The flaw exists in the LFS token validation logic where the system does not properly cross-reference the token's associated user context with the target repository's access control lists. This creates a scenario where LFS tokens, which should be scoped to specific repositories, can be used to access any repository owned by the authenticated user, regardless of the original token's intended scope.
The operational impact of this vulnerability extends beyond simple data access, as it enables potential data exfiltration and modification of repositories that users believe are protected. Attackers could exploit this flaw to read sensitive files from repositories they own, potentially accessing confidential source code, configuration files, or other proprietary information. The write capability allows for more severe consequences including repository corruption, unauthorized code commits, or the deployment of malicious code within the user's own repositories. This vulnerability particularly affects organizations that rely heavily on GitLab's LFS functionality for managing large binary files, as it could enable attackers to manipulate version-controlled assets or access sensitive data stored in repositories. The impact is compounded by the fact that the vulnerability affects such a broad range of versions, making it difficult for organizations to determine if their systems are exposed.
Organizations should implement immediate mitigations including upgrading to the patched versions 17.0.6, 17.1.4, and 17.2.2 respectively, or applying the relevant security patches provided by GitLab. Network segmentation and monitoring should be enhanced to detect unusual LFS token usage patterns, particularly when tokens are used to access repositories outside of normal operational boundaries. The vulnerability demonstrates the importance of implementing comprehensive access control testing and continuous security validation, as highlighted by ATT&CK technique T1078 which addresses valid accounts and privilege escalation. Administrators should also review existing LFS token policies and consider implementing additional verification steps to ensure that token usage aligns with the principle of least privilege. Regular security audits of access control mechanisms and automated testing of permission boundaries should be part of the security posture to prevent similar vulnerabilities from persisting in the future.