CVE-2019-12844 in TeamCity
Summary
by MITRE
A possible stored JavaScript injection was detected on one of the JetBrains TeamCity pages. The issue was fixed in TeamCity 2018.2.3.
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Analysis
by VulDB Data Team • 10/17/2023
The vulnerability identified as CVE-2019-12844 represents a stored cross-site scripting flaw within JetBrains TeamCity continuous integration and deployment platform. This security weakness was discovered in TeamCity versions prior to 2018.2.3 and specifically affected a particular page within the application's web interface where user-supplied input was not properly sanitized before being rendered back to users. The vulnerability falls under the category of stored XSS attacks where malicious JavaScript code can be injected into the application's database and subsequently executed whenever other users view the affected page. This type of vulnerability is particularly dangerous because the malicious payload persists in the system and affects multiple users without requiring them to click on any links or perform specific actions beyond viewing the compromised content. The flaw represents a failure in input validation and output encoding mechanisms that should have prevented untrusted data from being executed as code within the browser context. This vulnerability directly maps to CWE-79 which defines the weakness of cross-site scripting and aligns with ATT&CK technique T1203 which describes exploitation of web application vulnerabilities to execute arbitrary code.
The technical implementation of this stored JavaScript injection flaw likely occurred when TeamCity processed user input through a web form or API endpoint that stored data without proper sanitization. When other users accessed the affected page, the malicious script would execute in their browser context, potentially allowing attackers to steal session cookies, perform actions on behalf of users, or redirect them to malicious websites. The vulnerability's impact extends beyond simple data theft as it could enable attackers to establish persistent access to the TeamCity environment and potentially escalate privileges within the CI/CD pipeline. The fact that this was a stored vulnerability means that the malicious code was not limited to a single request but remained embedded in the application's database and executed whenever the affected page was accessed. Attackers could exploit this by injecting malicious scripts through legitimate user interfaces such as build configuration forms, comments, or project descriptions that were then displayed to other users. The remediation implemented in TeamCity 2018.2.3 involved strengthening input validation mechanisms and ensuring proper output encoding of user-supplied content to prevent script execution in browser contexts. This fix aligns with security best practices for preventing XSS vulnerabilities as outlined in OWASP's XSS Prevention Cheat Sheet and demonstrates the importance of proper data sanitization in web applications.
The operational impact of CVE-2019-12844 extends beyond immediate exploitation risks to encompass potential long-term security consequences for organizations relying on TeamCity for their continuous integration processes. Organizations using affected TeamCity versions faced significant exposure since the vulnerability could enable attackers to gain access to sensitive build artifacts, source code repositories, and deployment credentials that are typically handled within CI/CD systems. The persistent nature of stored XSS means that even after initial exploitation, attackers could maintain access to the system for extended periods, potentially compromising multiple builds and deployments over time. The vulnerability also posed risks to the integrity of the software development lifecycle, as attackers could inject malicious code into build processes or manipulate build results to hide their activities. Security teams needed to urgently assess their TeamCity environments for potential exploitation and implement immediate mitigations while planning for the mandatory upgrade to version 2018.2.3 or later. The incident highlighted the critical importance of keeping CI/CD platforms updated and implementing proper security controls for user input handling in web applications. Organizations should have conducted thorough security assessments of their TeamCity installations and reviewed access controls to minimize the potential impact of such vulnerabilities. This case serves as a reminder that even development tools used for security automation can contain vulnerabilities that attackers can exploit to compromise the entire development infrastructure. The remediation process required careful coordination to ensure that the upgrade did not disrupt ongoing build processes while also verifying that the fix properly addressed the stored XSS conditions in all affected pages.