JetBrains TeamCity Guest User Access Scanner

JetBrains TeamCity is a continuous integration and delivery server developed by JetBrains. It is widely used by software development teams around the globe to automate their development processes, including building, testing, and deploying applications. The tool supports various programming languages and build tools, making it a versatile solution for diverse development environments. Companies rely on TeamCity for its robust feature set, easy configuration, and integration capabilities with multiple version control systems. Its intuitive UI and plugin-rich ecosystem enable teams to streamline their workflows and improve productivity. The TeamCity platform is often hosted within organizations to ensure quick access and security of development pipelines.

Guest User Access in JetBrains TeamCity allows anonymous users to access certain parts of the TeamCity UI without requiring authentication. This feature, while useful for some scenarios, can pose potential security risks if misconfigured or left enabled inadvertently. Malicious users could exploit this access to gain insights into the system architecture or ongoing projects within the organization. It could also provide an opportunity to gather sensitive data or metadata that might aid in more targeted attacks. Proper configuration and access management must be ensured to mitigate such risks. Teams should carefully evaluate the necessity of Guest User Access and apply strict access controls where possible.

This vulnerability arises when TeamCity's guest login feature is enabled, allowing unauthenticated users to access the system. The vulnerable endpoint typically includes paths like "/guestLogin.html", which should redirect to pages such as "/overview.html" if accessed by guest accounts. The response headers often include specific session-related parameters like "TCSESSIONID", indicating successful entry as a guest. Ensuring that this endpoint is not publicly accessible is crucial in preventing unauthorized data exposure. System administrators must periodically review configuration settings and audit accessibility to sensitive endpoints.

Exploiting this vulnerability could allow attackers to obtain unauthorized access to internal project documentation, settings, and possibly lead to information disclosure. The exposure of such information could assist attackers in crafting more sophisticated attack vectors against the organization. It might also lead to leakage of intellectual property or business-critical build and deployment scripts. By identifying and securing misconfigured access points, organizations can safeguard their development environment. Depending on the severity of the access, further illicit activities such as data manipulation or interference with the CI/CD pipeline could also occur.

REFERENCES

• https://ph33r.medium.com/misconfig-in-teamcity-panel-lead-to-auth-bypass-in-apache-org-exploit-146f6a1a4e2b
• https://www.jetbrains.com/help/teamcity/guest-user.html