CVE-2017-12196 in Undertow
Summary
by MITRE
undertow before versions 1.4.18.SP1, 2.0.2.Final, 1.4.24.Final was found vulnerable when using Digest authentication, the server does not ensure that the value of URI in the Authorization header matches the URI in HTTP request line. This allows the attacker to cause a MITM attack and access the desired content on the server.
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Analysis
by VulDB Data Team • 02/28/2023
The vulnerability identified as CVE-2017-12196 affects the Undertow web server implementation across multiple version lines including 1.4.18.SP1, 2.0.2.Final, and 1.4.24.Final. This weakness resides in the digest authentication mechanism where the server fails to validate that the URI value present in the Authorization header precisely matches the URI specified in the HTTP request line. The flaw represents a critical security gap that undermines the integrity of the authentication process and creates opportunities for malicious actors to exploit the system.
The technical nature of this vulnerability stems from inadequate input validation within the digest authentication flow. When a client makes an HTTP request using digest authentication, the Authorization header contains various components including the URI being accessed. The server should verify that this URI matches exactly with the one specified in the initial request line to prevent unauthorized access. However, Undertow versions prior to the patched releases failed to perform this crucial validation step, allowing attackers to manipulate the URI component in the Authorization header without detection.
This vulnerability directly enables man-in-the-middle attack scenarios where adversaries can intercept and modify authentication headers. An attacker who successfully exploits this weakness can gain unauthorized access to protected resources by crafting malicious Authorization headers with different URI values while maintaining valid authentication credentials. The impact extends beyond simple access control bypass as it can potentially allow privilege escalation or data theft from authenticated sessions.
The operational consequences of this vulnerability are severe for organizations relying on Undertow servers with digest authentication enabled. Attackers can leverage this weakness to access sensitive content, modify data, or perform actions they would not normally be authorized to execute. The vulnerability affects the fundamental security model of digest authentication, which is designed to provide protection against password interception attacks while maintaining session integrity.
Security professionals should consider this vulnerability in relation to CWE-287 which addresses improper authentication issues, and ATT&CK technique T1212 which covers exploitation of credentials. The flaw aligns with the broader category of authentication bypass vulnerabilities that can compromise entire application security postures. Organizations should prioritize immediate patching of affected Undertow installations and consider implementing additional monitoring for suspicious authentication header patterns.
Mitigation strategies include upgrading to patched versions of Undertow where the URI validation has been properly implemented. System administrators should also implement network-level monitoring to detect anomalous Authorization header patterns and consider disabling digest authentication in favor of more secure alternatives such as OAuth or token-based authentication. Regular security assessments should verify that authentication mechanisms properly validate all header components and that no similar validation gaps exist in other server components or applications.