CVE-2018-1443 in SAML-based Single Sign-On
Summary
by MITRE
An XML parsing vulnerability affects IBM SAML-based single sign-on (SSO) systems (IBM Security Access Manager 9.0.0 - 9.0.4 and IBM Tivoli Federated Identity Manager 6.2 - 6.0.2.) This vulnerability can allow an attacker with authenticated access to trick SAML systems into authenticating as a different user without knowledge of the victim users password. IBM X-Force ID: 139754.
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Analysis
by VulDB Data Team • 02/17/2023
This vulnerability represents a critical XML parsing flaw in IBM's SAML-based single sign-on implementations that affects multiple versions of IBM Security Access Manager and IBM Tivoli Federated Identity Manager. The vulnerability stems from insufficient validation of SAML assertions during the authentication process, creating a potential for privilege escalation and unauthorized access within federated identity environments. The flaw specifically manifests when the system processes malformed XML data within SAML responses, allowing attackers to manipulate authentication flows through carefully crafted malicious assertions.
The technical implementation of this vulnerability leverages XML external entity (XXE) processing weaknesses in the SAML parsing components, enabling attackers to inject malicious XML content that can be interpreted by the underlying XML parser. This type of vulnerability maps directly to CWE-611 (Improper Restriction of XML External Entity Reference) and falls under the broader category of XML injection attacks that have been documented in various security frameworks including the OWASP Top Ten. The attack vector requires an authenticated session to exploit, but once successful, allows for unauthorized user impersonation within the federated identity system.
From an operational impact perspective, this vulnerability creates significant security risks for organizations relying on IBM's SAML-based authentication systems, as it enables attackers to bypass normal authentication controls and assume the identity of other users within the system. The vulnerability specifically affects the authentication delegation mechanisms that are fundamental to federated identity management, potentially allowing for complete compromise of user sessions and access to sensitive resources. The attack can be executed without knowledge of victim passwords, making it particularly dangerous in environments where password-based authentication is the primary security control.
Organizations should implement immediate mitigations including updating to patched versions of IBM Security Access Manager and IBM Tivoli Federated Identity Manager, implementing proper XML parser configuration to disable external entity processing, and strengthening monitoring of SAML assertion processing within authentication logs. The vulnerability also highlights the importance of proper input validation in federated identity systems and aligns with ATT&CK technique T1550.001 (Use of Valid Credentials) as it enables attackers to leverage legitimate authentication processes to gain unauthorized access. Security teams should also consider implementing additional authentication controls such as multi-factor authentication and enhanced session management policies to reduce the impact of such vulnerabilities in their environments.