CVE-2023-21553 Overview
CVE-2023-21553 is a Remote Code Execution (RCE) vulnerability affecting Microsoft Azure DevOps Server. This vulnerability allows authenticated attackers with low privileges to execute arbitrary code on vulnerable Azure DevOps Server instances through network-based attacks. The vulnerability is classified under CWE-94 (Improper Control of Generation of Code / Code Injection), indicating that the flaw stems from improper handling of code generation or injection vectors within the application.
Critical Impact
Successful exploitation of this vulnerability could allow an authenticated attacker to achieve remote code execution on affected Azure DevOps Server instances, potentially compromising the integrity, confidentiality, and availability of critical development infrastructure and source code repositories.
Affected Products
- Microsoft Azure DevOps Server 2020.1.2
- Microsoft Azure DevOps Server 2020.1.2 Patch 1
- Microsoft Azure DevOps Server 2020.1.2 Patch 2
- Microsoft Azure DevOps Server 2020.1.2 Patch 3
- Microsoft Azure DevOps Server 2020.1.2 Patch 4
Discovery Timeline
- February 14, 2023 - CVE-2023-21553 published to NVD
- November 21, 2024 - Last updated in NVD database
Technical Details for CVE-2023-21553
Vulnerability Analysis
This vulnerability exists within Microsoft Azure DevOps Server, specifically in versions within the 2020.1.2 branch. The flaw is categorized as a code injection vulnerability (CWE-94), which occurs when an application improperly handles external input that can influence the generation or execution of code.
The attack requires network access to the target Azure DevOps Server instance and low-level authenticated access. While the attack complexity is high—indicating that exploitation requires specific conditions or additional preparation—successful exploitation results in complete compromise of confidentiality, integrity, and availability of the affected system.
Azure DevOps Server serves as a critical piece of infrastructure for software development teams, managing source code repositories, build pipelines, and deployment configurations. Compromise of this system could lead to supply chain attacks, intellectual property theft, or injection of malicious code into software builds.
Root Cause
The vulnerability stems from improper control of code generation within Azure DevOps Server (CWE-94). This class of vulnerability occurs when the application constructs code or commands using externally-influenced input without proper validation or sanitization. In the context of Azure DevOps Server, this could involve the processing of user-supplied data in build definitions, pipeline configurations, or other server-side processing components.
Attack Vector
The attack vector is network-based, requiring the attacker to have authenticated access to the Azure DevOps Server instance with at least low-privilege credentials. The high attack complexity suggests that exploitation may require specific server configurations, timing conditions, or additional reconnaissance to successfully trigger the vulnerability.
An attacker would typically need to:
- Obtain valid credentials for the Azure DevOps Server instance
- Identify a vulnerable input vector that allows code injection
- Craft a malicious payload that exploits the improper code generation handling
- Execute the attack to achieve remote code execution on the server
The vulnerability does not require user interaction, meaning an attacker with network access and valid credentials can exploit it without additional social engineering.
Detection Methods for CVE-2023-21553
Indicators of Compromise
- Unusual process execution originating from Azure DevOps Server application pools or services
- Unexpected outbound network connections from the Azure DevOps Server host
- Anomalous authentication patterns or access to Azure DevOps Server APIs
- Suspicious modifications to build pipelines, release definitions, or repository content
Detection Strategies
- Monitor Azure DevOps Server logs for unusual API requests or authentication anomalies
- Implement endpoint detection and response (EDR) solutions to identify malicious code execution patterns
- Review IIS logs for suspicious requests targeting Azure DevOps Server endpoints
- Deploy network monitoring to detect unexpected traffic patterns from DevOps infrastructure
Monitoring Recommendations
- Enable comprehensive audit logging on Azure DevOps Server instances
- Configure alerts for unusual service account behavior or privilege escalation attempts
- Implement file integrity monitoring on Azure DevOps Server installation directories
- Monitor for changes to critical configuration files and pipeline definitions
How to Mitigate CVE-2023-21553
Immediate Actions Required
- Apply the latest security updates from Microsoft for Azure DevOps Server
- Review and restrict network access to Azure DevOps Server instances
- Audit user accounts and remove unnecessary or excessive privileges
- Implement network segmentation to isolate DevOps infrastructure
Patch Information
Microsoft has released security updates addressing this vulnerability. Organizations should consult the Microsoft Security Response Center advisory for detailed patching guidance and download links. The patch addresses the code injection vulnerability in affected Azure DevOps Server 2020.1.2 versions.
Workarounds
- Restrict network access to Azure DevOps Server to trusted IP ranges only
- Implement strong authentication mechanisms including multi-factor authentication
- Apply the principle of least privilege to all Azure DevOps Server user accounts
- Consider temporarily isolating Azure DevOps Server instances until patches can be applied
# Example: Restrict IIS binding to specific IP addresses for Azure DevOps Server
# This can help limit network exposure while awaiting patch deployment
# PowerShell command to review current IIS bindings
Get-WebBinding -Name "Azure DevOps Server"
# Consider implementing IP restrictions via IIS URL Rewrite rules
# or Windows Firewall to limit access to trusted networks only
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
