CVE-2011-3302 in Firewall Services Module Software
Summary
by MITRE
Cisco Adaptive Security Appliances (ASA) 5500 series devices, and the ASA Services module in Cisco Catalyst 6500 series devices, with software 7.0 before 7.0(8.13), 7.1 and 7.2 before 7.2(5.4), 8.0 before 8.0(5.25), 8.1 and 8.2 before 8.2(5.11), 8.3 before 8.3(2.23), 8.4 before 8.4(2.6), and 8.5 before 8.5(1.1) and Cisco Firewall Services Module (aka FWSM) 3.1 before 3.1(21), 3.2 before 3.2(22), 4.0 before 4.0(16), and 4.1 before 4.1(7) allow remote attackers to cause a denial of service (device reload) via crafted SunRPC traffic, aka Bug IDs CSCto92398 and CSCtq09989.
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Analysis
by VulDB Data Team • 11/23/2021
The vulnerability described in CVE-2011-3302 represents a critical denial of service flaw affecting Cisco Adaptive Security Appliances and Firewall Services Module devices. This issue specifically targets the handling of SunRPC (Sun Remote Procedure Call) traffic within the affected software versions, creating a condition where remote attackers can exploit malformed RPC requests to force device reloads. The vulnerability affects multiple generations of Cisco ASA and FWSM products, spanning from software version 7.0 through 8.5 releases, as well as various FWSM versions from 3.1 to 4.1, making it a widespread concern across enterprise network security infrastructure. The flaw manifests when the device processes crafted SunRPC traffic, leading to an unexpected system restart that disrupts network connectivity and availability.
The technical root cause of this vulnerability lies in insufficient input validation within the SunRPC processing module of Cisco's security appliances. When the affected devices receive specially crafted SunRPC packets, the parsing logic fails to properly handle malformed or unexpected data structures, resulting in a memory corruption condition that ultimately triggers a system crash and automatic device reload. This behavior aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow scenarios. The vulnerability exploits a classic input validation weakness where the device does not adequately sanitize incoming RPC traffic before processing it, allowing attackers to manipulate the parsing routines through carefully constructed payload data that exceeds expected parameter boundaries.
The operational impact of CVE-2011-3302 extends beyond simple service disruption, as it can lead to significant network availability issues in enterprise environments. When exploited successfully, the vulnerability forces devices to reload their operating systems, potentially causing temporary network outages that can affect critical business operations. The attack vector is particularly concerning because it requires no authentication and can be executed remotely, making it accessible to any attacker with network access to the vulnerable devices. According to ATT&CK framework, this vulnerability maps to T1499.004, which covers network denial of service attacks, and T1595.001, representing network reconnaissance activities that could precede exploitation. Organizations with multiple affected devices face the risk of cascading failures, where the reload of one device could impact network routing and security policies across interconnected systems.
Mitigation strategies for this vulnerability require immediate software updates to the latest available patches for all affected Cisco ASA and FWSM versions. Cisco released security advisories and patches addressing this specific flaw, and organizations should prioritize deployment of these updates across their network infrastructure. Network segmentation and access control measures can provide additional protection by limiting exposure of vulnerable devices to untrusted networks. Implementing traffic filtering rules to restrict SunRPC traffic to only trusted sources represents another defensive approach, though this may impact legitimate network operations that depend on RPC services. Security monitoring should include detection of unusual device reload patterns and anomalous RPC traffic patterns that could indicate exploitation attempts. The vulnerability highlights the importance of maintaining current security patches and conducting regular vulnerability assessments to identify and remediate similar issues before they can be exploited by malicious actors. Organizations should also consider implementing network access control lists and firewall rules to limit the exposure of vulnerable devices while patches are being deployed.