CVE-2024-36470: JetBrains TeamCity Auth Bypass Flaw

CVE-2024-36470 Overview

CVE-2024-36470 is a critical authentication bypass vulnerability affecting JetBrains TeamCity, a widely-used continuous integration and continuous delivery (CI/CD) server. This vulnerability allows attackers to bypass authentication mechanisms in specific edge cases, potentially gaining unauthorized access to TeamCity instances without valid credentials.

Critical Impact

This authentication bypass vulnerability enables unauthenticated attackers to gain unauthorized access to TeamCity servers, potentially compromising CI/CD pipelines, source code repositories, and deployment credentials.

Affected Products

• JetBrains TeamCity versions before 2022.04.7
• JetBrains TeamCity versions before 2022.10.6
• JetBrains TeamCity versions before 2023.05.6
• JetBrains TeamCity versions before 2023.11.5

Discovery Timeline

• 2024-05-29 - CVE-2024-36470 published to NVD
• 2025-02-07 - Last updated in NVD database

Technical Details for CVE-2024-36470

Vulnerability Analysis

CVE-2024-36470 represents a critical authentication bypass vulnerability in JetBrains TeamCity that allows attackers to circumvent authentication controls under specific edge case conditions. The vulnerability is associated with CWE-288 (Authentication Bypass Using an Alternate Path or Channel) and CWE-306 (Missing Authentication for Critical Function).

TeamCity servers are high-value targets for attackers due to their central role in software development pipelines. A compromised TeamCity instance can provide attackers with access to source code, build artifacts, deployment credentials, and the ability to inject malicious code into software builds. The network-accessible nature of this vulnerability makes it particularly dangerous for internet-facing TeamCity installations.

Root Cause

The vulnerability stems from improper authentication validation logic that fails to properly enforce authentication requirements in specific edge case scenarios. This flaw is classified under CWE-288 (Authentication Bypass Using an Alternate Path or Channel) and CWE-306 (Missing Authentication for Critical Function), indicating that certain request paths or conditions can be exploited to access protected functionality without proper authentication.

The authentication mechanism does not adequately validate all possible access paths, allowing attackers to craft requests that bypass normal authentication checks. This type of flaw typically occurs when authentication middleware or filters do not cover all endpoints or when conditional authentication logic contains logical errors.

Attack Vector

The attack can be carried out remotely over the network without requiring any prior authentication or user interaction. An attacker would need to identify a TeamCity instance running a vulnerable version and craft requests that exploit the specific edge cases where authentication validation fails.

The network-based attack vector with low complexity requirements makes this vulnerability particularly concerning for organizations with internet-exposed TeamCity servers. Attackers can potentially leverage this vulnerability to gain initial access to development infrastructure, establish persistence, and pivot to other systems.

Due to the critical nature of CI/CD systems, successful exploitation could enable supply chain attacks where malicious code is injected into software builds, potentially affecting downstream users and customers of the compromised organization.

Detection Methods for CVE-2024-36470

Indicators of Compromise

• Unexpected authentication events or sessions from unknown IP addresses in TeamCity access logs
• Unusual administrative actions performed without corresponding valid user authentication
• New user accounts or permission changes created without authorized administrator activity
• Suspicious API requests to authentication endpoints with malformed or missing credentials

Detection Strategies

• Monitor TeamCity access logs for authentication anomalies, particularly failed or bypassed authentication attempts
• Implement network-level monitoring for unusual traffic patterns to TeamCity servers
• Deploy web application firewalls (WAF) with rules to detect authentication bypass attempts
• Enable detailed audit logging in TeamCity to capture all administrative and sensitive operations

Monitoring Recommendations

• Configure alerting for any administrative changes made to TeamCity without corresponding user authentication
• Implement log aggregation and correlation to identify patterns indicative of exploitation attempts
• Monitor for unusual access patterns to TeamCity build configurations and project settings
• Track API usage patterns and flag requests that bypass normal authentication flows

How to Mitigate CVE-2024-36470

Immediate Actions Required

• Upgrade TeamCity to a patched version immediately: 2022.04.7, 2022.10.6, 2023.05.6, or 2023.11.5 or later
• Restrict network access to TeamCity servers using firewall rules and network segmentation
• Audit recent TeamCity access logs for signs of unauthorized access or suspicious activity
• Review and rotate any credentials stored in TeamCity, including deployment keys and service account passwords

Patch Information

JetBrains has released security patches addressing this vulnerability in the following versions:

• TeamCity 2022.04.7 and later
• TeamCity 2022.10.6 and later
• TeamCity 2023.05.6 and later
• TeamCity 2023.11.5 and later

Organizations should upgrade to the latest patched version for their respective release branch. Detailed information about security fixes is available from the JetBrains Security Issues Fixed advisory page.

Workarounds

• Place TeamCity servers behind a VPN or reverse proxy with additional authentication requirements
• Implement IP allowlisting to restrict access to TeamCity from trusted networks only
• Enable multi-factor authentication for all TeamCity user accounts
• Consider temporarily taking internet-facing TeamCity instances offline until patches can be applied

# Example: Restrict TeamCity access using iptables
# Allow access only from trusted internal network
iptables -A INPUT -p tcp --dport 8111 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 8111 -j DROP