CVE-2006-0561 in Secure Access
Summary
by MITRE
Cisco Secure Access Control Server (ACS) 3.x for Windows stores ACS administrator passwords and the master key in the registry with insecure permissions, which allows local users and remote administrators to decrypt the passwords by using Microsoft s cryptographic API functions to obtain the plaintext version of the master key.
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Analysis
by VulDB Data Team • 06/17/2019
The vulnerability identified as CVE-2006-0561 affects Cisco Secure Access Control Server version 3.x running on Windows platforms, representing a critical security flaw in the handling of cryptographic credentials. This issue stems from improper permission settings on registry entries that store sensitive administrative passwords and the master key used for encryption within the ACS system. The vulnerability exposes fundamental weaknesses in the access control mechanisms implemented by Cisco's authentication server software.
The technical flaw manifests through insecure registry permissions that allow unauthorized users to access cryptographic keys and password data stored in the Windows registry. When local users or remote administrators exploit this weakness, they can leverage Microsoft's cryptographic API functions to extract the master key in plaintext format. This process bypasses the intended encryption protection mechanisms and enables attackers to decrypt previously protected administrator passwords. The vulnerability specifically targets the Windows registry storage mechanism where Cisco ACS maintains its cryptographic materials, creating a direct path for credential compromise.
The operational impact of this vulnerability extends beyond simple credential theft, as it provides attackers with elevated privileges within the network access control environment. Once an attacker obtains the plaintext master key, they can decrypt all stored administrator passwords, effectively compromising the entire access control infrastructure. This weakness undermines the fundamental security model of the Cisco ACS system, where the master key serves as the foundation for protecting sensitive authentication data. The vulnerability affects both local users who may have system access and remote administrators who could potentially exploit network-based access to the registry entries.
Security professionals should recognize this issue as a classic example of insecure cryptographic key storage, aligning with CWE-310 and CWE-312 categories that address cryptographic failures and insecure data storage. The vulnerability also maps to ATT&CK techniques involving credential access and privilege escalation, as attackers can leverage the compromised credentials to gain deeper system access. Organizations should implement immediate registry permission hardening measures, ensuring that only authorized system processes can access the cryptographic storage locations. The remediation approach requires careful attention to Windows registry security settings and the implementation of proper access controls that align with security best practices for cryptographic key management.
This vulnerability highlights the critical importance of proper access control implementation in security infrastructure components and demonstrates how seemingly minor configuration flaws can lead to complete system compromise. The issue emphasizes the need for regular security audits of cryptographic storage mechanisms and proper adherence to security standards such as those defined by NIST for cryptographic key management practices. Organizations using Cisco ACS 3.x should consider immediate upgrades to patched versions or implement compensating controls to mitigate the risk of credential compromise through registry-based attacks.