CVE-2012-4661 in Cisco
Summary
by MITRE
Stack-based buffer overflow in 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(2.34), 8.4 before 8.4(4.4), 8.5 before 8.5(1.13), and 8.6 before 8.6(1.3) and the Firewall Services Module (FWSM) 4.1 before 4.1(9) in Cisco Catalyst 6500 series switches and 7600 series routers might allow remote attackers to execute arbitrary code via a crafted DCERPC packet, aka Bug IDs CSCtr21359 and CSCtr27522.
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Analysis
by VulDB Data Team • 04/18/2021
This vulnerability represents a critical stack-based buffer overflow flaw within the DCERPC inspection engine of Cisco's security infrastructure products. The vulnerability affects multiple device families including the ASA 5500 series adaptive security appliances, ASA Services Module (ASASM) in Catalyst 6500 series devices, and Firewall Services Module (FWSM) in Catalyst 6500 and 7600 series routers. The flaw manifests in software versions where the inspection engine fails to properly validate input lengths when processing DCERPC (Distributed Computing Environment Remote Procedure Call) packets, creating a condition where maliciously crafted packets can overwrite adjacent memory locations on the stack. This type of vulnerability falls under CWE-121, stack-based buffer overflow, and represents a fundamental memory safety issue that can be exploited to achieve arbitrary code execution. The affected software versions span across multiple major releases including ASA software 8.3 through 8.6 and FWSM software 4.1, with specific patch levels indicating the vulnerability persists until the mentioned service pack releases.
The operational impact of this vulnerability is severe as it enables remote attackers to execute arbitrary code on affected devices without requiring authentication. Attackers can craft specially formatted DCERPC packets that, when processed by the vulnerable inspection engine, trigger the buffer overflow condition. This allows for complete compromise of the affected security appliance, potentially enabling attackers to gain full administrative control over the device. The implications extend beyond simple code execution as compromised devices can be used as stepping stones for further network infiltration, allowing attackers to establish persistent access points within the network infrastructure. The vulnerability is particularly dangerous in network security contexts where these devices serve as primary firewalls and security gateways, as the compromise of such devices can lead to complete network exposure and data breaches.
The exploitation of this vulnerability aligns with ATT&CK technique T1059.007 for command and script interpreter, specifically targeting the Windows command shell through DCERPC protocol manipulation. The attack vector leverages the DCERPC protocol which is commonly used for Windows services communication, making it a natural target for exploitation in enterprise environments where Windows services are prevalent. Network security professionals should note that this vulnerability affects both hardware-based security appliances and software modules, indicating a systemic issue within Cisco's inspection engine architecture that requires comprehensive patching across all affected platforms. The vulnerability demonstrates the importance of input validation in protocol inspection engines and highlights the risks associated with complex network security processing logic that must handle diverse and potentially malicious inputs. Organizations should implement immediate mitigation strategies including software updates, network segmentation, and monitoring for suspicious DCERPC traffic patterns to prevent exploitation attempts.
Cisco's response to this vulnerability included the release of security advisories and patch updates for the affected software versions, specifically addressing the buffer overflow conditions in the DCERPC inspection engine. The patching process required careful consideration of the device uptime requirements and network availability constraints, as these security appliances typically operate in mission-critical network environments. Security teams implementing mitigations should verify the specific software versions and apply the appropriate patches according to Cisco's recommended remediation procedures. The vulnerability also underscores the importance of network protocol analysis and monitoring capabilities that can detect anomalous DCERPC traffic patterns, as these may indicate attempted exploitation activities. Organizations should consider implementing network access control lists and intrusion detection systems that can identify and block suspicious DCERPC packet structures to provide additional defense-in-depth measures against this specific vulnerability class.