CVE-2002-0848 in VPN 500 Concentrator
Summary
by MITRE
Cisco VPN 5000 series concentrator hardware 6.0.21.0002 and earlier, and 5.2.23.0003 and earlier, when using RADIUS with a challenge type of Password Authentication Protocol (PAP) or Challenge, sends the user password in cleartext in a validation retry request, which could allow remote attackers to steal passwords via sniffing.
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Analysis
by VulDB Data Team • 06/17/2019
The vulnerability identified as CVE-2002-0848 affects Cisco VPN 5000 series concentrators running specific firmware versions, representing a critical security flaw in the authentication mechanism of remote access VPN solutions. This issue specifically impacts systems utilizing RADIUS authentication with Password Authentication Protocol or Challenge response mechanisms, creating a significant exposure point for credential theft. The vulnerability resides in the protocol implementation where authentication credentials are transmitted without proper encryption, making it susceptible to interception by malicious actors monitoring network traffic.
The technical flaw manifests in the improper handling of authentication retry requests within the RADIUS protocol stack of these Cisco devices. When a user authentication fails and a retry is initiated, the system sends the user password in plaintext format rather than utilizing secure transmission methods. This cleartext transmission occurs during the validation retry process, which is a standard mechanism designed to handle authentication failures. The vulnerability affects both hardware versions 6.0.21.0002 and earlier, as well as version 5.2.23.0003 and earlier, indicating a widespread issue across multiple firmware releases of the Cisco VPN 5000 series concentrators. The flaw directly violates security best practices for credential transmission and represents a failure in implementing proper cryptographic protections during authentication processes.
The operational impact of this vulnerability is severe and far-reaching for organizations relying on Cisco VPN 5000 series concentrators for remote network access. Remote attackers capable of performing network sniffing operations can easily capture authentication credentials during retry attempts, potentially gaining unauthorized access to corporate networks, sensitive data, and privileged systems. This vulnerability creates an attack surface that requires minimal technical expertise to exploit, making it particularly dangerous for organizations with limited security monitoring capabilities. The exposure period extends beyond individual authentication failures to include any scenario where retry requests are processed, potentially affecting multiple users and authentication sessions over time.
Organizations affected by this vulnerability should implement immediate mitigation strategies to protect their network infrastructure from credential theft attacks. The primary recommendation involves upgrading to patched firmware versions that address the cleartext transmission issue, ensuring that all Cisco VPN 5000 series concentrators operate on versions that properly encrypt authentication credentials during retry requests. Network administrators should also consider implementing additional security controls such as network segmentation, enhanced monitoring for unusual authentication patterns, and deployment of intrusion detection systems capable of identifying credential interception attempts. The vulnerability aligns with CWE-312 (Cleartext Storage of Sensitive Information) and represents a clear violation of the principle of least privilege in authentication mechanisms. From an ATT&CK framework perspective, this vulnerability maps to techniques involving credential access through network sniffing and credential dumping, making it a valuable target for adversaries seeking persistent access to corporate networks through compromised remote access points.