CVE-2020-7911 in TeamCity
Summary
by MITRE
In JetBrains TeamCity before 2019.2, several user-level pages were vulnerable to XSS.
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Analysis
by VulDB Data Team • 01/31/2020
The vulnerability identified as CVE-2020-7911 affects JetBrains TeamCity versions prior to 2019.2 and represents a cross-site scripting vulnerability that impacts multiple user-level pages within the application. This issue allows attackers to inject malicious scripts into web pages viewed by other users, potentially compromising the security of the entire TeamCity environment. The vulnerability exists due to insufficient input validation and output encoding mechanisms within the web interface components that handle user-provided data. The affected pages likely process user input without proper sanitization, creating opportunities for attackers to execute malicious JavaScript code in the context of other users' browsers.
This vulnerability falls under the CWE-79 category of Cross-Site Scripting, specifically representing a stored XSS attack vector where malicious payloads can persist in the application's database or configuration files. The operational impact of this vulnerability is significant as it can enable attackers to steal session cookies, perform unauthorized actions on behalf of users, or redirect victims to malicious websites. Given that TeamCity is a continuous integration and deployment platform, the compromise of user sessions could lead to unauthorized code deployments, access to sensitive build configurations, and potential exposure of source code repositories. The vulnerability affects the authentication and authorization mechanisms of the platform, potentially allowing attackers to escalate privileges or gain access to restricted administrative functions.
The technical exploitation of this vulnerability requires an attacker to first gain access to a user account or find a way to inject malicious content through legitimate user input fields. Attackers could leverage this vulnerability by crafting malicious payloads that would be executed when other users view affected pages, potentially including build results, user profiles, or configuration settings. The vulnerability demonstrates poor security practices in input validation and output encoding, which are fundamental requirements for preventing XSS attacks according to OWASP Top Ten and the ATT&CK framework's T1203 technique for Exploitation for Credential Access. Organizations using TeamCity versions before 2019.2 should immediately implement security patches and consider implementing additional security controls such as Content Security Policy headers and input validation mechanisms.
The impact extends beyond simple script execution as this vulnerability could enable attackers to establish persistent access to the TeamCity environment through session hijacking or by creating backdoor access points. The affected user-level pages likely include build result displays, user profile management, project configuration interfaces, and other interactive elements that process user input. Security teams should conduct thorough assessments of their TeamCity installations to identify all potentially affected components and ensure proper patching procedures are followed. The vulnerability also highlights the importance of regular security updates and the need for comprehensive security testing of web applications, particularly those handling sensitive operational data. Organizations should also review their incident response procedures to ensure they can quickly detect and respond to potential exploitation attempts. The remediation process requires not only applying the official patches but also implementing additional monitoring and logging mechanisms to detect suspicious activities that might indicate exploitation attempts.