CVE-2019-0743 in Team Foundation Server
Summary
by MITRE
A Cross-site Scripting (XSS) vulnerability exists when Team Foundation Server does not properly sanitize user provided input, aka 'Team Foundation Server Cross-site Scripting Vulnerability'. This CVE ID is unique from CVE-2019-0742.
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Analysis
by VulDB Data Team • 05/13/2020
The vulnerability identified as CVE-2019-0743 represents a critical cross-site scripting weakness within Microsoft Team Foundation Server that arises from inadequate input sanitization mechanisms. This flaw specifically affects the server's handling of user-provided data within web interfaces, creating an environment where malicious actors can inject harmful scripts into web pages viewed by other users. The vulnerability manifests when the system fails to properly validate and sanitize input parameters before rendering them in web responses, allowing attackers to execute arbitrary JavaScript code within the context of a victim's browser session. The issue is particularly concerning in collaborative development environments where Team Foundation Server serves as a central platform for project management, version control, and team communication, as it can potentially compromise the entire development workflow and expose sensitive project information.
The technical implementation of this XSS vulnerability stems from the server's insufficient filtering of user input across multiple web application interfaces and API endpoints. When users submit data through various input fields, form submissions, or URL parameters, the system should apply rigorous sanitization processes to remove or encode potentially dangerous characters and script tags. However, in this specific case, certain input paths within Team Foundation Server bypass these security controls, allowing malicious payloads to persist and execute when subsequent users access the affected pages. The vulnerability's impact extends beyond simple script execution as it can enable session hijacking, data theft, and privilege escalation attacks when combined with other exploitation techniques. This weakness aligns with CWE-79 which categorizes cross-site scripting vulnerabilities as a result of insufficient input validation and output encoding.
The operational implications of CVE-2019-0743 are severe for organizations relying on Team Foundation Server for their development operations. Attackers exploiting this vulnerability can gain unauthorized access to sensitive project information, manipulate code repositories, and potentially escalate privileges within the development environment. The vulnerability creates a persistent threat vector that remains active as long as the affected server version is operational, making it particularly dangerous for continuous integration and deployment pipelines where automated processes might be compromised. Organizations may experience data breaches, intellectual property theft, and disruption of development workflows that can result in significant financial and reputational damage. The attack surface is particularly broad given that Team Foundation Server typically serves as a central hub for multiple development teams and stakeholders, amplifying the potential impact of a successful XSS exploitation.
Mitigation strategies for CVE-2019-0743 should focus on implementing comprehensive input validation and output encoding mechanisms across all Team Foundation Server components. Organizations should immediately apply Microsoft's security patches and updates to address the vulnerability, while also implementing additional protective measures such as content security policies and web application firewalls to provide defense-in-depth. The implementation of proper input sanitization libraries and regular security code reviews can help prevent similar vulnerabilities from emerging in future development cycles. Security teams should also conduct comprehensive penetration testing and vulnerability assessments to identify other potential XSS vectors within the server infrastructure. From an ATT&CK framework perspective, this vulnerability maps to techniques involving command and control communication and credential access, as attackers can use the XSS payload to establish persistent access to the development environment and potentially extract sensitive credentials or access tokens stored in browser sessions. Organizations should also consider implementing user training programs to recognize and report potential social engineering attempts that might exploit this vulnerability.