CVE-2020-24379 in Web Server
Summary
by MITRE
WebDAV implementation in Yaws web server versions 1.81 to 2.0.7 is vulnerable to XXE injection.
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Analysis
by VulDB Data Team • 06/16/2024
The vulnerability identified as CVE-2020-24379 represents a critical XML External Entity injection flaw within the WebDAV implementation of the Yaws web server software. This vulnerability affects versions ranging from 1.81 through 2.0.7, creating a significant security risk for organizations relying on this web server implementation. The issue stems from insufficient input validation and sanitization within the WebDAV module, which processes XML-based requests without properly restricting external entity references. This weakness allows malicious actors to inject malicious XML entities that can be processed by the underlying XML parser, potentially leading to unauthorized data access, server-side request forgery, or even remote code execution depending on the server configuration and available resources.
The technical exploitation of this vulnerability occurs through the WebDAV protocol implementation which handles XML-formatted requests for file operations and server management tasks. When a client submits a specially crafted WebDAV request containing malicious XML entities, the Yaws server processes these entities without adequate validation, enabling attackers to reference external resources or execute arbitrary commands. This flaw aligns with CWE-611, which categorizes XML External Entity processing vulnerabilities, and specifically maps to the broader category of insecure XML processing within web applications. The vulnerability is particularly dangerous because WebDAV operations often require elevated privileges and can access system resources that would otherwise be restricted, making the potential impact significantly greater than typical XML injection flaws.
The operational impact of CVE-2020-24379 extends beyond simple data theft or service disruption, as it can enable attackers to gain deeper system access and potentially establish persistent footholds within network environments. Organizations using affected Yaws versions may experience unauthorized access to sensitive files, directory traversal attacks, or server compromise through command execution capabilities that the XML parser enables. The vulnerability affects the fundamental WebDAV functionality that many organizations use for file sharing, collaboration, and remote management operations, making it a prime target for attackers seeking to exploit web server implementations. According to ATT&CK framework category T1190, this vulnerability could be leveraged for initial access through web application exploitation, while T1059 indicates potential for command execution once the vulnerability is successfully exploited.
Mitigation strategies for CVE-2020-24379 should focus on immediate version upgrades to patched releases of the Yaws web server software, as the vulnerability has been addressed in subsequent releases. Organizations should also implement strict XML input validation and disable external entity processing in all XML parsers used by the WebDAV implementation. Network segmentation and firewall rules can help limit access to WebDAV endpoints, while comprehensive monitoring should be deployed to detect suspicious XML requests. Additionally, implementing web application firewalls and security scanning tools that can identify and block XXE injection attempts will provide additional layers of protection. The vulnerability demonstrates the importance of proper XML processing security measures and aligns with industry best practices outlined in OWASP Top Ten and NIST cybersecurity guidelines for preventing XML external entity injection attacks. Organizations should also consider implementing automated patch management processes to ensure timely remediation of similar vulnerabilities in the future, as the WebDAV protocol's continued use requires careful attention to XML security controls and proper input sanitization measures.