CVE-2023-21564 in Azure DevOps Server
Summary
by MITRE • 02/14/2023
Azure DevOps Server Cross-Site Scripting Vulnerability
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Analysis
by VulDB Data Team • 03/15/2023
The Azure DevOps Server Cross-Site Scripting vulnerability represents a critical security flaw that allows attackers to inject malicious scripts into web applications through improperly validated user input. This vulnerability specifically affects the Azure DevOps Server environment and enables unauthorized code execution within the context of a victim's browser session. The flaw exists in the server's handling of user-supplied data that is subsequently rendered in web interfaces without adequate sanitization or encoding mechanisms. According to CWE-79, this vulnerability falls under the category of Cross-Site Scripting, which is one of the most prevalent and dangerous web application security issues identified by the CWE project. The vulnerability can be exploited by an attacker who gains the ability to inject malicious scripts into web pages viewed by other users, potentially leading to session hijacking, data theft, or further exploitation of the compromised environment.
The technical implementation of this vulnerability stems from inadequate input validation and output encoding within the Azure DevOps Server's web interfaces. When users submit data through various forms, fields, or API endpoints, the server fails to properly sanitize or encode this input before rendering it in HTML contexts. This allows attackers to inject malicious JavaScript code that executes in the browser context of authenticated users. The vulnerability is particularly concerning because Azure DevOps Server is commonly used for managing sensitive development workflows, source code repositories, and deployment pipelines, making it an attractive target for attackers seeking to compromise development environments. The attack surface includes various user interfaces such as work item forms, code review comments, project descriptions, and other editable fields where user input is processed and displayed.
The operational impact of CVE-2023-21564 extends beyond simple script injection, as it can enable attackers to escalate privileges and access sensitive information within the Azure DevOps environment. Successful exploitation could allow threat actors to view confidential project data, manipulate work items, access source code repositories, or even perform administrative actions if the attacker can obtain elevated privileges. The vulnerability creates opportunities for attackers to establish persistent access through techniques such as cookie theft, session hijacking, or redirecting users to malicious sites. From an ATT&CK framework perspective, this vulnerability maps to techniques such as T1059.007 (Scripting) and T1566.001 (Phishing), as attackers can leverage the XSS flaw to deliver malicious payloads and conduct social engineering campaigns. The impact is particularly severe in enterprise environments where Azure DevOps Server serves as a central hub for development activities and contains sensitive intellectual property.
Mitigation strategies for this vulnerability should focus on implementing comprehensive input validation and output encoding mechanisms throughout the Azure DevOps Server application. Organizations should ensure that all user-supplied data is properly sanitized before being rendered in web contexts, utilizing techniques such as HTML encoding, context-appropriate escaping, and Content Security Policy (CSP) headers. Microsoft has released patches and updates to address this vulnerability, and administrators should immediately apply the relevant security updates to their Azure DevOps Server installations. Additional defensive measures include implementing web application firewalls, monitoring for suspicious user activities, and conducting regular security assessments of the development environment. The vulnerability also highlights the importance of secure coding practices and input validation controls, which align with security standards such as OWASP Top Ten and NIST Cybersecurity Framework. Organizations should also consider implementing multi-factor authentication, role-based access controls, and regular security training for development teams to reduce the overall risk exposure.