CVE-2012-4663 in Firewall Services Module
Summary
by MITRE
The DCERPC inspection engine on Cisco Adaptive Security Appliances (ASA) 5500 series devices, and the ASA Services Module (ASASM) in Cisco Catalyst 6500 series devices, with software 8.3 before 8.3(2.25), 8.4 before 8.4(2.5), and 8.5 before 8.5(1.13) and the Firewall Services Module (FWSM) 4.1 before 4.1(7) in Cisco Catalyst 6500 series switches and 7600 series routers allows remote attackers to cause a denial of service (device reload) via a crafted DCERPC packet, aka Bug IDs CSCtr21346 and CSCtr27521.
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Analysis
by VulDB Data Team • 04/18/2021
The vulnerability described in CVE-2012-4663 represents a critical denial of service weakness affecting Cisco Adaptive Security Appliances and related network infrastructure devices. This flaw resides within the DCERPC inspection engine component of Cisco's security solutions, specifically targeting the 5500 series ASA devices and the ASA Services Module (ASASM) in Catalyst 6500 series equipment. The vulnerability also impacts the Firewall Services Module (FWSM) in Catalyst 6500 and 7600 series routers. The affected software versions span multiple release lines including ASA software 8.3 before 8.3(2.25), 8.4 before 8.4(2.5), 8.5 before 8.5(1.13), and FWSM 4.1 before 4.1(7). The security implications extend beyond simple service disruption as this weakness enables remote attackers to trigger complete device reloads, effectively rendering the targeted security infrastructure unavailable to protect network traffic.
The technical flaw manifests through the improper handling of crafted DCERPC (Distributed Computing Environment Remote Procedure Call) packets by the inspection engine. DCERPC is a protocol used for communication between distributed applications, commonly employed in Windows environments for remote administration and service calls. When the vulnerable Cisco devices receive specially crafted DCERPC packets, the inspection engine fails to properly validate or process these malformed requests, leading to a buffer overflow condition or memory corruption scenario. This processing error ultimately results in the device crashing and automatically reloading its operating system. The vulnerability specifically affects the protocol inspection functionality that monitors and validates network traffic passing through the security appliance, making it particularly dangerous as it can be exploited without requiring authentication or physical access to the device. The flaw operates at the network protocol level where the device's security engine attempts to parse and validate DCERPC traffic, creating an execution path that leads to system instability.
The operational impact of this vulnerability is severe and potentially catastrophic for organizations relying on Cisco ASA and FWSM devices for network security. Remote attackers can exploit this weakness to cause unauthorized device reloads, effectively creating a denial of service condition that can last from several minutes to hours depending on the device's configuration and recovery process. The automated device reload process can disrupt network connectivity, potentially affecting critical business operations, and may require manual intervention to restore services. The vulnerability is particularly concerning because it affects core network security infrastructure, meaning that successful exploitation can leave networks temporarily unprotected against other threats. Organizations may experience service degradation or complete network outages, especially in environments where redundant security appliances are not properly configured to handle the sudden loss of primary security devices. The impact extends beyond simple availability issues as the device reload process may also cause temporary loss of security policy enforcement and logging capabilities, leaving networks more vulnerable during the recovery period.
Mitigation strategies for CVE-2012-4663 should prioritize immediate software updates and patches from Cisco, specifically addressing the identified software versions that contain the vulnerability. Organizations should apply the relevant security patches, such as ASA software versions 8.3(2.25), 8.4(2.5), and 8.5(1.13) for the affected ASA devices, and FWSM version 4.1(7) for the Catalyst switches and routers. Network administrators should also implement network segmentation and access controls to limit exposure of vulnerable devices to untrusted networks, particularly by filtering or blocking DCERPC traffic where possible. The implementation of intrusion detection systems can help identify exploitation attempts, though the vulnerability's nature makes detection challenging due to its execution within normal protocol processing. Additional protective measures include configuring logging and monitoring to detect unusual device behavior or frequent restarts that may indicate exploitation attempts. Organizations should also consider implementing redundant security appliances or failover mechanisms to maintain network protection during device maintenance or recovery periods, as the automatic reload process can create temporary security gaps. This vulnerability aligns with CWE-121, which addresses stack-based buffer overflow conditions, and maps to ATT&CK technique T1499.004 for network denial of service attacks, demonstrating the importance of maintaining current security software versions and implementing layered defensive measures.