CVE-2005-4499 in Secure ACS
Summary
by MITRE
The Downloadable RADIUS ACLs feature in Cisco PIX and VPN 3000 concentrators, when creating an ACL on the Cisco Secure Access Control Server (CS ACS), generates a random internal name for an ACL that is also used as a hidden user name and password, which allows remote attackers to gain privileges by sniffing the username from the cleartext portion of a RADIUS session, then using the password to log in to another device that uses CS ACS.
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Analysis
by VulDB Data Team • 07/02/2024
The vulnerability described in CVE-2005-4499 represents a critical security flaw in Cisco's PIX and VPN 3000 concentrators that affects the Downloadable RADIUS ACLs functionality. This issue stems from the insecure generation of internal identifiers within the Cisco Secure Access Control Server environment, creating a significant attack surface that can be exploited by remote threat actors. The vulnerability specifically manifests when the system creates a random internal name for Access Control Lists that serves a dual purpose as both an ACL identifier and a hidden username and password combination for authentication purposes.
The technical implementation of this flaw involves the creation of a predictable authentication mechanism where the randomly generated internal name becomes embedded within RADIUS session data in cleartext format. This design flaw violates fundamental security principles by exposing authentication credentials within network protocols that are inherently susceptible to interception. The vulnerability operates at the network protocol level, specifically within the RADIUS authentication framework where the system fails to properly separate authentication mechanisms from access control list management functions. This creates a situation where network traffic monitoring tools can capture the cleartext credentials, effectively providing attackers with a direct path to unauthorized access.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass potential lateral movement within network environments that utilize Cisco Secure Access Control Server for authentication management. Attackers who successfully intercept the cleartext credentials can leverage them to authenticate to other devices within the same authentication domain, creating a chain of compromise that can span multiple network segments. This vulnerability directly relates to CWE-312 (Cleartext Storage of Sensitive Information) and CWE-259 (Use of Hard-coded Password) while also aligning with ATT&CK techniques involving credential access and privilege escalation. The attack vector is particularly dangerous because it requires minimal technical sophistication and can be executed through passive network monitoring rather than active exploitation.
Mitigation strategies for this vulnerability should focus on implementing network segmentation to isolate authentication services from general network traffic, deploying RADIUS encryption mechanisms such as EAP-TLS or PEAP to prevent cleartext credential exposure, and implementing network access control policies that restrict unauthorized access to authentication servers. Organizations should also consider implementing monitoring solutions that can detect anomalous authentication patterns and credential reuse attempts. The remediation process requires careful coordination between network security teams and authentication service administrators to ensure proper configuration of encryption protocols and access control policies. Additionally, regular security audits should verify that authentication credentials are not being transmitted in cleartext and that proper separation of concerns exists between access control list management and authentication credential generation within the Cisco Secure Access Control Server environment.