CVE-2011-5063 in Tomcat
Summary
by MITRE
The HTTP Digest Access Authentication implementation in Apache Tomcat 5.5.x before 5.5.34, 6.x before 6.0.33, and 7.x before 7.0.12 does not check realm values, which might allow remote attackers to bypass intended access restrictions by leveraging the availability of a protection space with weaker authentication or authorization requirements, a different vulnerability than CVE-2011-1184.
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Analysis
by VulDB Data Team • 11/28/2021
The vulnerability described in CVE-2011-5063 represents a critical weakness in Apache Tomcat's HTTP Digest Access Authentication mechanism that fundamentally undermines the security of web applications relying on this authentication method. This flaw exists in multiple versions of Tomcat including 5.5.x before 5.5.34, 6.x before 6.0.33, and 7.x before 7.0.12, making it a widespread concern affecting a significant portion of web application servers in production environments. The vulnerability stems from the implementation's failure to properly validate realm values during the authentication process, creating a potential pathway for attackers to exploit authentication mechanisms through carefully crafted requests that leverage the availability of weaker protection spaces within the same application.
The technical flaw in this vulnerability resides in the digest authentication implementation where Tomcat fails to validate the realm parameter that is part of the HTTP Digest authentication challenge. Normally, the realm parameter serves as a contextual identifier that defines the protection space and ensures that authentication credentials are only valid within the intended scope. When this validation is bypassed, attackers can manipulate the authentication process by presenting credentials that were originally intended for one protection space but are accepted in another with potentially weaker security requirements. This creates a scenario where an attacker might discover a realm with less stringent access controls and then leverage that knowledge to gain unauthorized access to resources that should otherwise be protected by stronger authentication mechanisms. The vulnerability is particularly concerning because it operates at the protocol level of HTTP authentication rather than at the application level, making it difficult to detect through traditional application security measures.
The operational impact of this vulnerability extends beyond simple unauthorized access to encompass broader security implications for web applications deployed on affected Tomcat versions. Attackers can exploit this weakness to bypass intended access controls by identifying protection spaces with weaker authentication requirements and then using those credentials to access restricted resources within the application. This type of attack aligns with techniques described in the ATT&CK framework under the credential access and privilege escalation domains, specifically targeting the exploitation of authentication mechanisms to gain unauthorized access to protected resources. The vulnerability creates a situation where the security model of the application becomes compromised, as the authentication system fails to properly enforce the boundaries between different protection spaces. Organizations using affected Tomcat versions may experience unauthorized data access, privilege escalation, and potential complete system compromise depending on the application's security architecture and the resources being protected.
The remediation strategy for this vulnerability requires immediate patching of affected Tomcat installations to versions that properly validate realm parameters during the digest authentication process. System administrators should prioritize upgrading to Tomcat 5.5.34, 6.0.33, or 7.0.12 respectively, depending on their current version, as these releases contain the necessary fixes to address the realm validation issue. Additionally, organizations should implement monitoring and logging of authentication attempts to detect potential exploitation attempts, particularly focusing on unusual patterns of realm usage or authentication failures that might indicate an attack. The vulnerability's classification under CWE-287, which addresses improper authentication, highlights the fundamental nature of this flaw and underscores the importance of proper authentication mechanism implementation. Security teams should also consider implementing additional authentication layers or alternative authentication methods for critical applications until the patching process is complete, as this vulnerability can be exploited remotely without requiring any special privileges or local access to the system.