CVE-2011-3301 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 CSCtq06062 and CSCtq09986.
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Analysis
by VulDB Data Team • 11/23/2021
The vulnerability identified as CVE-2011-3301 affects Cisco Adaptive Security Appliances (ASA) 5500 series devices and ASA Services modules in Catalyst 6500 series devices, along with Cisco Firewall Services Module (FWSM) devices. This flaw represents a critical denial of service vulnerability that can be exploited remotely through specially crafted SunRPC traffic. The affected software versions span multiple releases including ASA software versions 7.0 through 8.5 and FWSM versions 3.1 through 4.1, with specific patch levels required to mitigate the risk. The vulnerability was documented under Bug IDs CSCtq06062 and CSCtq09986, highlighting its significance in the Cisco security landscape.
The technical implementation of this vulnerability stems from improper handling of SunRPC (Sun Remote Procedure Call) traffic within the affected Cisco security appliances. When these devices receive malformed or specially crafted SunRPC packets, the processing logic fails to properly validate incoming data structures, leading to memory corruption or stack overflow conditions. This improper input validation represents a classic example of CWE-121, which encompasses buffer overflow conditions, and CWE-122, which addresses insufficient validation of length of input buffers. The flaw occurs at the network protocol processing layer where the appliance attempts to parse and handle RPC requests without adequate bounds checking or error recovery mechanisms.
The operational impact of this vulnerability is severe as it allows remote attackers to trigger a complete device reload or system crash without requiring authentication credentials. This means that an attacker positioned anywhere on the network can exploit this weakness to cause service disruption, potentially resulting in extended downtime for critical network security infrastructure. The vulnerability affects the availability aspect of the CIA triad, making it particularly dangerous in environments where network security appliances are critical for maintaining network integrity and access control. Organizations relying on these devices for firewall protection, intrusion prevention, and network segmentation could experience complete service outages, potentially exposing their networks to further attacks during the recovery period. The vulnerability also aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and represents a significant risk for organizations following the MITRE ATT&CK framework for threat analysis.
Mitigation strategies for this vulnerability require immediate implementation of software patches provided by Cisco, specifically targeting the affected software versions mentioned in the advisory. Organizations should prioritize updating their ASA and FWSM devices to the latest recommended releases, particularly versions 7.0(8.13), 7.2(5.4), 8.0(5.25), 8.2(5.11), 8.3(2.23), 8.4(2.6), and 8.5(1.1) for ASA software, and the corresponding FWSM patch levels. Network administrators should also implement access control measures to limit exposure, such as restricting SunRPC traffic to trusted networks or implementing firewall rules that filter out suspicious RPC traffic patterns. Additional defensive measures include monitoring network traffic for anomalous SunRPC activity, implementing intrusion detection systems with signatures for this specific vulnerability, and establishing incident response procedures for rapid deployment of patches during security events. The vulnerability demonstrates the importance of maintaining current security patches and highlights the risks associated with legacy network security infrastructure that may not receive ongoing support or updates.