CVE-2019-0871 in Azure DevOps Server
Summary
by MITRE
A Cross-site Scripting (XSS) vulnerability exists when Azure DevOps Server and Team Foundation Server do not properly sanitize user provided input, aka 'Azure DevOps Server and Team Foundation Server Cross-site Scripting Vulnerability'. This CVE ID is unique from CVE-2019-0866, CVE-2019-0867, CVE-2019-0868, CVE-2019-0870.
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Analysis
by VulDB Data Team • 08/28/2023
The vulnerability described in CVE-2019-0871 represents a critical cross-site scripting flaw affecting Azure DevOps Server and Team Foundation Server versions prior to the security updates. This weakness stems from insufficient input validation and sanitization mechanisms within the web application framework, allowing malicious actors to inject malicious scripts into web pages viewed by other users. The vulnerability specifically manifests when the system processes user-provided data without adequately filtering or encoding special characters that could be interpreted as executable code by web browsers. The affected platforms handle numerous user interactions including work item descriptions, comments, and other editable fields where unfiltered input could be stored and subsequently rendered to other users. This particular flaw enables attackers to execute arbitrary JavaScript code within the context of a victim's browser session, potentially compromising user credentials, session tokens, or access to sensitive project data.
The technical implementation of this vulnerability aligns with CWE-79, which defines Cross-site Scripting as a common weakness where web applications fail to properly validate or encode user-supplied data before incorporating it into dynamic web content. The flaw operates at the application layer where user input flows directly into HTML output without appropriate sanitization measures, creating an attack surface that can be exploited through various vectors including form submissions, URL parameters, or direct input fields within the Azure DevOps interface. Attackers can craft malicious payloads that, when executed, can perform actions such as stealing cookies, redirecting users to malicious sites, or manipulating the application interface to gain unauthorized access. The vulnerability's impact extends beyond simple script execution as it can facilitate more sophisticated attacks including session hijacking, data exfiltration, and privilege escalation within the context of the affected server environment.
The operational implications of this vulnerability are significant for organizations relying on Azure DevOps Server and Team Foundation Server for their development workflows and collaboration platforms. Given that these systems typically contain sensitive project information, source code repositories, build artifacts, and user credentials, a successful exploitation could lead to complete compromise of development environments and intellectual property theft. The vulnerability affects the core functionality of these platforms, potentially allowing attackers to inject malicious code into work items, comments, or other user-generated content that gets displayed to other team members. This creates a persistent threat vector where compromised users may unknowingly execute malicious code simply by viewing affected content, making the attack surface particularly broad and difficult to contain. Organizations with extensive use of these platforms face substantial risk of unauthorized access to sensitive development data and potential disruption of critical software development processes.
Mitigation strategies for CVE-2019-0871 should prioritize immediate implementation of the security patches released by Microsoft as part of their regular update cycle. Organizations must ensure comprehensive testing of the applied patches in staging environments before deployment to production systems to prevent potential service disruptions. Beyond patching, implementing robust input validation and output encoding mechanisms can provide additional defense-in-depth measures. The implementation of Content Security Policy headers and proper HTML encoding of user-supplied data can significantly reduce the risk of successful exploitation even if the underlying vulnerability persists. Security teams should conduct thorough vulnerability assessments of their Azure DevOps environments, particularly focusing on user input fields and areas where external data might be rendered in web interfaces. Regular monitoring and logging of user activities within the platform can help detect anomalous behavior indicative of exploitation attempts. Organizations should also consider implementing web application firewalls and network-based security controls to provide additional protection layers against potential exploitation attempts. The vulnerability's classification under ATT&CK technique T1566 suggests that organizations should also enhance their user education and awareness programs to prevent social engineering attacks that might leverage this vulnerability for initial access.