CVE-2020-15825 in TeamCity
Summary
by MITRE
In JetBrains TeamCity before 2020.1, users with the Modify Group permission can elevate other users' privileges.
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Analysis
by VulDB Data Team • 08/09/2020
This vulnerability exists in JetBrains TeamCity versions prior to 2020.1 and represents a privilege escalation flaw that allows authenticated users with the Modify Group permission to elevate the privileges of other users within the system. The vulnerability stems from insufficient access control mechanisms that fail to properly validate user permissions when modifying group memberships and associated permissions. Attackers exploiting this weakness can manipulate group assignments to grant elevated access rights to accounts they control, effectively bypassing the intended security boundaries between different user roles and permission levels.
The technical implementation of this vulnerability demonstrates a classic broken access control scenario where the application fails to enforce proper authorization checks during group modification operations. When a user with Modify Group permission attempts to add or remove members from a group, the system does not adequately verify whether the modifying user has the authority to grant the specific permissions that the target user would receive through group membership. This creates a path for privilege escalation where malicious actors can leverage their existing Modify Group rights to indirectly grant themselves or others higher-level permissions such as administrator access or additional project-specific privileges.
From an operational impact perspective, this vulnerability significantly undermines the security posture of TeamCity installations by allowing unauthorized privilege escalation without requiring administrative credentials or direct access to the system's core administrative functions. The flaw can be exploited by users who may have legitimate but limited access to modify group configurations, making it particularly dangerous in environments where multiple users have varying degrees of access control permissions. Organizations using affected versions of TeamCity face potential data breaches, unauthorized system modifications, and complete compromise of the build server environment if this vulnerability is exploited.
The vulnerability aligns with CWE-285, which addresses improper authorization in access control systems, and can be mapped to ATT&CK technique T1078.004 for Valid Accounts and T1484.001 for Group Policy Modification. Organizations should immediately upgrade to TeamCity version 2020.1 or later where this vulnerability has been addressed through enhanced permission validation mechanisms. Additional mitigations include implementing least privilege principles, regularly auditing group memberships and user permissions, and monitoring for suspicious group modification activities. Security teams should also consider implementing additional access control layers and conducting regular security assessments to identify potential privilege escalation paths within their CI/CD environments.