CVE-2011-3299 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 CSCto92380 and CSCtq09972.
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Analysis
by VulDB Data Team • 11/23/2021
The vulnerability described in CVE-2011-3299 represents a critical denial of service flaw affecting Cisco Adaptive Security Appliances and Firewall Services Module devices across multiple software versions. This vulnerability specifically targets the handling of crafted SunRPC traffic, which is a remote procedure call protocol commonly used for distributed computing applications. The affected systems include Cisco ASA 5500 series devices and ASA Services modules in Catalyst 6500 series devices, along with various FWSM versions. The flaw manifests when these security appliances process malformed SunRPC packets, leading to unauthorized device reloads that effectively disrupt network connectivity and service availability.
The technical implementation of this vulnerability stems from inadequate input validation within the SunRPC processing components of Cisco's security appliances. When these devices receive specially crafted SunRPC traffic, the malformed packets trigger unexpected behavior in the processing logic, causing the system to crash and automatically reload its operating system. This behavior aligns with CWE-129, which describes improper validation of input ranges, and CWE-134, which addresses use of format strings in a manner that can result in arbitrary code execution. The vulnerability exists at the protocol parsing layer where the system fails to properly sanitize incoming network traffic before processing it, creating a path for malicious actors to exploit the device's resource management mechanisms.
The operational impact of this vulnerability extends beyond simple service disruption to encompass significant business continuity concerns for organizations relying on Cisco ASA and FWSM devices for network security. The remote exploitation capability means that attackers can trigger device reboots from external networks without requiring physical access or authentication credentials, making this particularly dangerous in environments where network security is paramount. The vulnerability affects multiple software release branches, indicating a fundamental flaw in the codebase that was not properly addressed across different version lines. Organizations utilizing these devices face potential downtime that could impact critical network services, user access, and overall operational efficiency. The attack vector through SunRPC traffic suggests that this vulnerability could be exploited by attackers who have access to the network segment where these devices operate, potentially through network scanning or other reconnaissance activities.
Mitigation strategies for CVE-2011-3299 should prioritize immediate software updates to the latest available patches for affected Cisco ASA and FWSM versions. Organizations must ensure that all affected devices are upgraded to software versions that contain the necessary fixes for the SunRPC processing vulnerability. Network segmentation and access controls should be implemented to limit exposure of these devices to untrusted networks, while monitoring systems should be configured to detect unusual traffic patterns that might indicate exploitation attempts. The ATT&CK framework categorizes this vulnerability under T1499.004 for network denial of service and T1071.004 for application layer protocol usage, highlighting the need for comprehensive network monitoring and traffic analysis. Additional defensive measures include implementing firewall rules to restrict SunRPC traffic to only trusted sources, disabling unnecessary services where possible, and maintaining detailed logs of network traffic for forensic analysis in case of exploitation attempts. Organizations should also conduct vulnerability assessments to identify any additional unpatched devices within their network infrastructure that may be similarly affected by this class of vulnerability.