CVE-2002-0241 in ACS
Summary
by MITRE
NDSAuth.DLL in Cisco Secure Authentication Control Server (ACS) 3.0.1 does not check the Expired or Disabled state of users in the Novell Directory Services (NDS), which could allow those users to authenticate to the server.
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Analysis
by VulDB Data Team • 06/17/2019
The vulnerability described in CVE-2002-0241 represents a critical authentication flaw within Cisco Secure Authentication Control Server version 3.0.1 that specifically affects the NDSAuth.DLL component responsible for handling Novell Directory Services authentication. This issue stems from a fundamental design oversight in the authentication validation process where the system fails to properly verify user account status before granting access privileges. The flaw exists at the core of the authentication mechanism, specifically within the NDS integration layer that should be enforcing account expiration and disablement policies but instead allows compromised or terminated user accounts to bypass these security controls.
The technical implementation of this vulnerability demonstrates a failure in access control validation where the NDSAuth.DLL module processes authentication requests without performing adequate checks against user account status attributes within the Novell Directory Services. This represents a classic case of insufficient input validation and access control enforcement, categorized under CWE-284 Access Control Flaws. The authentication server essentially trusts the directory service without verifying that user accounts have not been marked as expired or disabled, creating a persistent backdoor for unauthorized access. This flaw operates at the application layer of the network security stack and directly impacts the principle of least privilege by allowing users who should be denied access to continue authenticating successfully.
The operational impact of this vulnerability extends beyond simple unauthorized access to encompass potential privilege escalation and lateral movement within networks that rely on Cisco Secure ACS for authentication. Attackers who gain access through this vulnerability can maintain persistent access to systems and resources that should have been restricted due to account expiration or administrative disablement. This weakness undermines the fundamental security model of authentication systems and creates opportunities for attackers to exploit compromised user accounts or accounts that have been intentionally disabled as part of security protocols. The vulnerability particularly affects environments where account lifecycle management is critical and where administrative controls are expected to be enforced by the authentication infrastructure.
Organizations should implement immediate mitigations including upgrading to patched versions of Cisco Secure ACS, implementing additional monitoring controls to detect unauthorized authentication attempts, and ensuring proper account lifecycle management procedures are enforced. The remediation process should include verifying that all user accounts are properly disabled or expired according to security policies and that these status changes are immediately reflected in the authentication infrastructure. Security teams should also consider implementing network segmentation and additional authentication layers to reduce the attack surface. This vulnerability aligns with ATT&CK technique T1078 Valid Accounts, as it allows adversaries to leverage legitimate credentials that should have been invalidated but were not properly enforced by the authentication system. The incident response implications require organizations to review their account management processes and ensure that authentication systems properly enforce all account status information from directory services.