CVE-2019-0777 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'.
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Analysis
by VulDB Data Team • 05/16/2020
The CVE-2019-0777 vulnerability represents a critical cross-site scripting flaw within Microsoft Team Foundation Server that enables malicious actors to inject arbitrary script code into web applications. This vulnerability stems from insufficient input validation and sanitization mechanisms within the TFS platform, specifically affecting how the system processes user-provided data in web interfaces. The flaw allows attackers to execute malicious scripts in the context of other users' browsers, potentially compromising the security of the entire development environment. The vulnerability is particularly concerning in enterprise settings where TFS serves as a central collaboration platform for software development teams, making it a prime target for adversaries seeking to exploit the trust relationships between users and the system.
The technical implementation of this XSS vulnerability occurs when TFS fails to properly sanitize or encode user input before rendering it in web pages. Attackers can craft malicious payloads that exploit this weakness by injecting script code into forms, URLs, or other input fields within the TFS interface. The vulnerability manifests when user-supplied data is directly reflected back to users without adequate security measures such as output encoding or content security policies. This allows attackers to execute scripts in the victim's browser context, potentially enabling session hijacking, credential theft, or data exfiltration. The flaw exists at the application layer where input validation should occur, and it specifically impacts the web-based components of TFS that handle user interactions and data display.
The operational impact of CVE-2019-0777 extends beyond simple script execution, as it can compromise the integrity of the entire development workflow within organizations using Team Foundation Server. Attackers can leverage this vulnerability to manipulate project data, steal sensitive development credentials, or gain unauthorized access to source code repositories. The attack surface is particularly broad since TFS is commonly used for managing source control, build processes, and team collaboration, making it a valuable target for adversaries seeking to disrupt development operations or extract intellectual property. The vulnerability can be exploited through various vectors including web forms, URL parameters, and user-generated content fields within the TFS interface, potentially affecting multiple users within the organization simultaneously.
Organizations should implement comprehensive mitigation strategies to address this vulnerability, beginning with immediate application of Microsoft's security patches and updates. The remediation process involves ensuring proper input validation and output encoding mechanisms are in place throughout the TFS application stack, with particular attention to web interfaces that process user input. Security controls should include implementing strict content security policies, enabling proper sanitization of all user-provided data, and deploying web application firewalls to detect and block malicious script injection attempts. Additionally, organizations should conduct thorough security assessments of their TFS environments, review access controls, and implement monitoring solutions to detect potential exploitation attempts. This vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws, and represents a typical attack pattern categorized under ATT&CK technique T1059.007 for script injection, highlighting the need for robust application security measures in development platforms.