CVE-2019-1076 in Azure DevOps 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 • 07/09/2020
The CVE-2019-1076 vulnerability represents a critical cross-site scripting flaw within Microsoft Team Foundation Server that exposes organizations to significant web application security risks. This vulnerability stems from insufficient input validation and sanitization mechanisms within the server's processing pipeline, allowing malicious actors to inject malicious scripts into web interfaces that are subsequently executed by unsuspecting users. The flaw specifically manifests when the system fails to properly sanitize user-provided data before rendering it within web pages, creating an attack vector that can be exploited across various interactive components of the TFS platform.
The technical exploitation of this vulnerability occurs through the manipulation of input fields and parameters that are processed by Team Foundation Server's web interface. Attackers can craft malicious payloads containing javascript code or other script-based attacks that are then stored or transmitted through the vulnerable system. When legitimate users interact with these maliciously crafted inputs, typically through project management interfaces, issue tracking systems, or collaborative features, the embedded scripts execute within the user's browser context. This behavior aligns with CWE-79 which specifically addresses cross-site scripting vulnerabilities and represents a fundamental failure in input validation and output encoding mechanisms. The vulnerability's impact is particularly severe as it can be leveraged to steal user sessions, access sensitive project data, manipulate workflow processes, or redirect users to malicious websites.
The operational implications of CVE-2019-1076 extend beyond simple script execution, creating a comprehensive attack surface that can compromise entire development environments and organizational security postures. Organizations utilizing Team Foundation Server become vulnerable to session hijacking attacks where attackers can impersonate legitimate users and gain unauthorized access to source code repositories, build artifacts, and sensitive project information. The vulnerability can be exploited through various attack vectors including but not limited to issue tracking forms, work item descriptions, comments, and project configuration interfaces. This presents a significant risk to software development lifecycle processes, as attackers could potentially inject malicious code into development workflows, compromise build systems, or manipulate project timelines and deliverables. The attack surface is further expanded when considering that TFS is often integrated with other Microsoft ecosystem components, potentially allowing lateral movement and privilege escalation within enterprise networks.
Mitigation strategies for CVE-2019-1076 should encompass both immediate patching and defensive configuration measures to protect against exploitation. Microsoft released security updates that address the vulnerability through enhanced input sanitization and output encoding mechanisms within TFS components, requiring organizations to apply the appropriate security patches promptly. Organizations should implement comprehensive input validation policies that enforce strict sanitization of all user-provided data before processing, utilizing parameterized queries and proper HTML encoding techniques. Network-level defenses including web application firewalls and content filtering systems can provide additional layers of protection by monitoring and blocking suspicious script patterns. Security teams should also implement regular vulnerability assessments and penetration testing to identify potential exploitation vectors, while establishing incident response procedures specifically designed to handle XSS-related security events. The remediation process should include comprehensive user education about recognizing and reporting suspicious activities within collaborative development environments, as well as implementing proper access controls and privilege management to limit the potential impact of successful exploitation attempts.