CVE-2018-1304 in Tomcat
Summary
by MITRE
The URL pattern of "" (the empty string) which exactly maps to the context root was not correctly handled in Apache Tomcat 9.0.0.M1 to 9.0.4, 8.5.0 to 8.5.27, 8.0.0.RC1 to 8.0.49 and 7.0.0 to 7.0.84 when used as part of a security constraint definition. This caused the constraint to be ignored. It was, therefore, possible for unauthorised users to gain access to web application resources that should have been protected. Only security constraints with a URL pattern of the empty string were affected.
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Analysis
by VulDB Data Team • 02/16/2023
The vulnerability described in CVE-2018-1304 represents a critical access control flaw within Apache Tomcat web server implementations across multiple versions. This issue specifically targets the handling of security constraints defined with empty string URL patterns, which should theoretically map to the application's root context. The flaw exists in versions ranging from the initial releases of Tomcat 9.0.0.M1 through 9.0.4, 8.5.0 through 8.5.27, 8.0.0.RC1 through 8.0.49, and 7.0.0 through 7.0.84, indicating a long-standing issue that affected major release lines. The vulnerability stems from the improper processing of empty string URL patterns in security constraint definitions, creating a scenario where legitimate access controls are bypassed due to incorrect pattern matching logic.
The technical implementation of this vulnerability involves the web server's security constraint evaluation mechanism failing to properly recognize empty string patterns as valid context root mappings. When administrators define security constraints using URL patterns that are empty strings, these constraints should logically apply to the entire application context root. However, due to the flawed implementation, the empty string pattern fails to match the actual context root, causing the security constraint to be completely ignored during request processing. This results in a situation where authenticated access controls that should prevent unauthorized access to protected resources are effectively neutralized, allowing any user to access content that should be restricted to authorized personnel only.
The operational impact of this vulnerability is severe as it fundamentally undermines the security model of web applications running on affected Tomcat versions. Attackers can exploit this weakness by simply accessing the application's root context, bypassing all security constraints that were intended to protect sensitive resources. This vulnerability aligns with CWE-284 Access Control Issues, specifically addressing improper access control where the system fails to properly enforce authorization checks. The flaw essentially creates a backdoor through which unauthorized users can gain access to protected application resources without proper authentication or authorization, potentially exposing sensitive data, administrative interfaces, or other protected components.
The security implications extend beyond simple unauthorized access to include potential data breaches and privilege escalation scenarios. Organizations using affected Tomcat versions may unknowingly expose their entire web applications to unauthorized access, as the vulnerability affects the core security constraint mechanism rather than specific application components. This type of vulnerability is particularly concerning because it operates at the web server level and affects the fundamental security controls that protect application resources. The vulnerability also relates to ATT&CK technique T1078 Valid Accounts, as it allows unauthorized access through bypassing legitimate access controls that should enforce proper authentication and authorization.
Mitigation strategies for this vulnerability require immediate patching of affected Tomcat installations to versions that have addressed the empty string URL pattern handling issue. System administrators should also review all security constraint definitions within their web applications to ensure that empty string patterns are properly handled or replaced with explicit root context patterns. Organizations should conduct comprehensive security audits to identify any applications running on affected versions and verify that access controls are functioning correctly. Additionally, implementing monitoring solutions to detect unauthorized access attempts to protected resources can help identify exploitation attempts before they result in data breaches. The vulnerability demonstrates the critical importance of proper URL pattern matching in security implementations and highlights the need for thorough testing of access control mechanisms, particularly those involving root context mappings and empty string handling.