CVE-2019-12841 in TeamCity
Summary
by MITRE
Incorrect handling of user input in ZIP extraction was detected in JetBrains TeamCity. The issue was fixed in TeamCity 2018.2.2.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 06/30/2020
The vulnerability identified as CVE-2019-12841 represents a critical input validation flaw within JetBrains TeamCity's ZIP file extraction functionality. This issue stems from inadequate sanitization of user-supplied data during archive processing operations, creating potential pathways for malicious exploitation. The vulnerability specifically manifests in how TeamCity handles file paths and names contained within ZIP archives, allowing for improper handling of special characters and directory traversal sequences. Organizations relying on TeamCity for continuous integration and deployment processes face significant risk when this vulnerability remains unaddressed, as it could enable attackers to manipulate the extraction process and potentially execute arbitrary code or access unauthorized system resources. The flaw particularly affects environments where TeamCity processes untrusted ZIP files from external sources or user uploads, making it a substantial concern for security-conscious organizations.
The technical implementation of this vulnerability falls under CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as directory traversal or path traversal attacks. Attackers can exploit this weakness by crafting malicious ZIP archives containing specially formatted file paths that bypass normal extraction restrictions. When TeamCity processes these archives, the flawed input handling allows for directory traversal sequences to be interpreted literally rather than being properly sanitized, potentially enabling attackers to write files outside of intended directories or access restricted system locations. This vulnerability operates at the application layer and requires user interaction through the upload or processing of malicious archives, making it a medium to high severity threat in environments where TeamCity serves as a central integration point for automated build processes.
The operational impact of CVE-2019-12841 extends beyond simple data integrity concerns, as it could enable attackers to compromise entire build servers or access sensitive information within the TeamCity environment. Organizations utilizing TeamCity for automated deployment workflows face potential exposure to code injection attacks, where malicious payloads could be embedded within ZIP archives and executed during normal build processes. The vulnerability particularly impacts continuous integration environments where automated systems process large volumes of code changes from multiple sources, creating opportunities for attackers to gain persistent access or escalate privileges within the build infrastructure. Additionally, the exploitation of this vulnerability could lead to denial of service conditions, data exfiltration, or complete compromise of the build environment, making it a critical concern for security teams managing enterprise software development pipelines.
Mitigation strategies for CVE-2019-12841 focus primarily on immediate software updates to TeamCity version 2018.2.2 or later, which contains the necessary patches to address the input validation issues. Organizations should implement comprehensive monitoring of ZIP file processing activities within their TeamCity instances to detect potential exploitation attempts, while also establishing strict access controls and limiting the sources of archives processed by the system. Security teams should consider implementing additional safeguards such as sandboxed environments for archive processing, automated signature verification for uploaded files, and regular security assessments of the TeamCity configuration. The vulnerability's remediation aligns with ATT&CK technique T1059.007 for execution through script interpreters, as exploitation could involve malicious scripts embedded within compromised ZIP archives. Organizations should also consider implementing network segmentation and firewall rules to limit access to TeamCity servers, reducing the attack surface and preventing unauthorized access to the build infrastructure.