CVE-2005-2841 in IOS
Summary
by MITRE
Buffer overflow in Firewall Authentication Proxy for FTP and/or Telnet Sessions for Cisco IOS 12.2ZH and 12.2ZL, 12.3 and 12.3T, and 12.4 and 12.4T allows remote attackers to cause a denial of service and possibly execute arbitrary code via crafted user authentication credentials.
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Analysis
by VulDB Data Team • 06/29/2025
The vulnerability identified as CVE-2005-2841 represents a critical buffer overflow flaw within Cisco IOS Firewall Authentication Proxy component that specifically affects versions 12.2ZH and 12.2ZL, 12.3 and 12.3T, and 12.4 and 12.4T. This security weakness resides in the authentication processing mechanism for FTP and Telnet sessions, creating a pathway for malicious actors to exploit the system through carefully crafted user credentials. The flaw stems from inadequate input validation and bounds checking within the authentication proxy module, which fails to properly handle excessive data lengths during credential processing. This vulnerability operates at the network infrastructure level, targeting the core authentication services that govern access to network resources through FTP and Telnet protocols, making it particularly dangerous for enterprise environments where these services remain active. The buffer overflow condition occurs when the system attempts to store authentication data exceeding the allocated memory buffer space, potentially leading to memory corruption and system instability.
The technical exploitation of this vulnerability leverages the inherent weakness in input handling within the Firewall Authentication Proxy functionality of Cisco IOS. When remote attackers submit specially crafted authentication credentials containing excessive data, the system's buffer management fails to properly validate the input length, resulting in memory overwrite conditions that can trigger system crashes or potentially enable code execution. This type of vulnerability maps directly to CWE-121, which describes stack-based buffer overflow conditions, and represents a classic example of improper input validation that allows attackers to manipulate memory structures. The attack vector is remote and does not require authentication to initiate the exploit, making it particularly dangerous as it can be triggered by any user attempting to establish FTP or Telnet connections to the affected network devices. The vulnerability's impact extends beyond simple denial of service as the memory corruption could potentially be leveraged to execute arbitrary code, providing attackers with unauthorized access to the network infrastructure.
The operational impact of CVE-2005-2841 manifests as both immediate denial of service conditions and potential long-term security compromise of network infrastructure. Organizations utilizing affected Cisco IOS versions face the risk of unauthorized network access, system outages, and potential data breaches when this vulnerability is successfully exploited. The flaw affects critical network services that many enterprises depend upon for remote access and file transfer operations, creating significant business continuity risks. From an attack perspective, this vulnerability aligns with ATT&CK technique T1190, which covers exploitation of remote services, and T1068, which involves local privilege escalation through system exploitation. The vulnerability's presence in multiple IOS release trains (12.2ZH, 12.2ZL, 12.3, 12.3T, 12.4, and 12.4T) indicates a widespread exposure across numerous network deployments, making it a high-priority target for attackers seeking to compromise enterprise network infrastructure. Organizations may experience service disruptions, unauthorized access to network resources, and potential data exfiltration through exploitation of this authentication bypass mechanism.
Mitigation strategies for CVE-2005-2841 require immediate implementation of security patches provided by Cisco, specifically addressing the buffer overflow conditions in the Firewall Authentication Proxy component. Network administrators should prioritize upgrading affected IOS versions to patched releases that contain proper input validation and memory management controls. The implementation of network segmentation and access controls can help limit the potential impact of exploitation by restricting access to vulnerable services and reducing the attack surface. Additionally, monitoring network traffic for unusual authentication patterns and implementing intrusion detection systems can help identify exploitation attempts. Organizations should also consider disabling FTP and Telnet services where possible, as these protocols are inherently insecure and vulnerable to various attacks. The remediation process should include thorough testing of patched firmware to ensure compatibility with existing network configurations and services. Security teams must also implement comprehensive vulnerability management processes that include regular assessment of network infrastructure for similar weaknesses, as this vulnerability demonstrates the importance of proper input validation in network security appliances. The remediation efforts should align with industry best practices for network security and include regular security audits to identify and address similar vulnerabilities in other network components.