CVE-2015-5253 in CXF
Summary
by MITRE
The SAML Web SSO module in Apache CXF before 2.7.18, 3.0.x before 3.0.7, and 3.1.x before 3.1.3 allows remote authenticated users to bypass authentication via a crafted SAML response with a valid signed assertion, related to a "wrapping attack."
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Analysis
by VulDB Data Team • 06/27/2022
The vulnerability identified as CVE-2015-5253 represents a critical authentication bypass flaw within the SAML Web SSO module of Apache CXF, affecting versions prior to 2.7.18, 3.0.7, and 3.1.3. This issue stems from a weakness in how the system processes SAML responses, specifically concerning the handling of signed assertions that enables malicious actors to exploit a wrapping attack vector. The flaw occurs when a remote authenticated user crafts a specially constructed SAML response that contains a validly signed assertion but manipulates the structure or content in a way that circumvents the intended authentication checks.
The technical implementation of this vulnerability involves a wrapping attack pattern where the malicious SAML response is constructed to appear legitimate while containing embedded elements that bypass the normal authentication flow. This attack exploits the trust relationship between the identity provider and service provider, leveraging the valid signature validation process to accept a response that has been manipulated to grant unauthorized access. The vulnerability specifically targets the SAML assertion processing logic within Apache CXF's Web SSO implementation, where the system fails to properly validate the integrity and structure of the entire SAML response envelope rather than just the embedded assertion.
The operational impact of this vulnerability is severe as it allows authenticated users to bypass authentication mechanisms entirely, potentially granting them access to protected resources and services that should only be available to authorized personnel. An attacker could exploit this vulnerability to gain unauthorized access to applications secured through SAML-based authentication, leading to data breaches, privilege escalation, and potential lateral movement within affected networks. The attack requires only a valid authenticated session to craft the malicious response, making it particularly dangerous as it can be executed by users who already have some level of access to the system.
Security mitigations for CVE-2015-5253 include immediate patching of Apache CXF installations to versions 2.7.18, 3.0.7, or 3.1.3 where the vulnerability has been addressed. Organizations should also implement additional monitoring and validation of SAML responses, including stricter parsing and validation of the entire SAML response structure rather than relying solely on assertion signatures. The fix addresses the wrapping attack by strengthening the validation process to ensure that SAML responses maintain proper structure and that embedded assertions cannot be manipulated to bypass authentication checks. This vulnerability aligns with CWE-284 Access Control Issues and can be categorized under ATT&CK technique T1078 Valid Accounts, as it exploits legitimate authentication mechanisms to gain unauthorized access to systems. Organizations should also consider implementing additional security controls such as multi-factor authentication and enhanced logging of authentication events to detect potential exploitation attempts.