CVE-2011-0394 in Firewall Services Module Software
Summary
by MITRE
Cisco Adaptive Security Appliances (ASA) 5500 series devices with software 7.0 before 7.0(8.11), 7.1 and 7.2 before 7.2(5.1), 8.0 before 8.0(5.19), 8.1 before 8.1(2.47), 8.2 before 8.2(2.19), and 8.3 before 8.3(1.8); Cisco PIX Security Appliances 500 series devices; and Cisco Firewall Services Module (aka FWSM) 3.1 before 3.1(20), 3.2 before 3.2(20), 4.0 before 4.0(15), and 4.1 before 4.1(5) allow remote attackers to cause a denial of service (device reload) via a malformed Skinny Client Control Protocol (SCCP) message, aka Bug IDs CSCtg69457 and CSCtl84952.
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Analysis
by VulDB Data Team • 12/01/2024
The vulnerability described in CVE-2011-0394 represents a critical denial of service weakness affecting Cisco's Adaptive Security Appliances and related security devices. This flaw specifically targets the Skinny Client Control Protocol implementation within these network security appliances, which are widely deployed for voice and data security in enterprise environments. The affected devices include the ASA 5500 series with various software versions, PIX 500 series devices, and Firewall Services Module configurations across multiple release branches. The vulnerability stems from insufficient input validation within the SCCP message processing subsystem, creating a condition where malformed protocol messages can trigger unexpected device behavior.
The technical execution of this vulnerability involves sending specially crafted SCCP messages that exploit a buffer overflow or parsing error within the device's control plane processing. When these malformed messages are received, they cause the device to enter an unstable state leading to complete system reload or reboot. The root cause aligns with CWE-121, which describes buffer overflow conditions, and CWE-122, which covers buffer overflow vulnerabilities. The flaw exists in the protocol parsing logic that fails to properly validate message lengths, content boundaries, or message structure before processing. This allows attackers to craft messages that exceed expected buffer sizes or contain malformed data structures that the device cannot handle gracefully.
From an operational perspective, this vulnerability presents a severe risk to network availability and business continuity. The remote exploitation capability means that attackers can trigger device reboots from outside the network perimeter, potentially leading to extended service interruptions. Network administrators face the challenge of maintaining voice and data security services while managing the risk of unauthenticated denial of service attacks. The impact extends beyond simple service disruption as device reloads can cause temporary loss of network security policies, requiring manual intervention to restore full functionality. Organizations using these devices may experience cascading effects on their network infrastructure, particularly in environments where these appliances serve as primary security gateways for voice communications.
The mitigation strategies for this vulnerability involve immediate software updates and patches from Cisco, specifically addressing the affected software versions mentioned in the advisory. Organizations should prioritize upgrading to patched versions of ASA software, PIX firmware, and FWSM releases to eliminate the parsing vulnerability. Network segmentation and access control measures can provide temporary protection by limiting network access to only trusted sources, reducing the attack surface for remote exploitation attempts. Implementing monitoring and alerting systems to detect unusual traffic patterns or device behavior can help identify potential exploitation attempts. Additionally, network administrators should consider disabling SCCP functionality where possible, as this protocol is primarily used for voice communication and may not be essential for all network environments. The vulnerability demonstrates the importance of maintaining current security patches and implementing defense-in-depth strategies to protect critical network infrastructure from remote exploitation attempts.