CVE-2011-3304 in ASA
Summary
by MITRE
Cisco Adaptive Security Appliances (ASA) 5500 series devices, and the ASA Services module in Cisco Catalyst 6500 series devices, with software 7.2 before 7.2(5.3), 8.0 before 8.0(5.25), 8.1 before 8.1(2.50), 8.2 before 8.2(5.11), 8.3 before 8.3(2.23), 8.4 before 8.4(2), and 8.5 before 8.5(1.1) allow remote attackers to cause a denial of service (device reload) via crafted MSN Instant Messenger traffic, aka Bug ID CSCtl67486.
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Analysis
by VulDB Data Team • 11/23/2021
The vulnerability identified as CVE-2011-3304 affects Cisco Adaptive Security Appliances (ASA) 5500 series devices and ASA Services modules in Cisco Catalyst 6500 series devices. This issue represents a significant denial of service weakness that can be exploited by remote attackers to force device reloads, thereby disrupting network security services. The affected software versions span multiple releases including 7.2 through 8.5, with specific patch levels required to remediate the issue. The vulnerability specifically targets the processing of MSN Instant Messenger traffic, demonstrating how seemingly benign messaging protocols can be weaponized to compromise network infrastructure availability.
The technical flaw resides in the improper handling of crafted MSN Instant Messenger packets by the ASA device's inspection mechanisms. When these devices encounter malformed or specially constructed MSN traffic, the processing routines fail to properly validate input data, leading to memory corruption or state inconsistencies that ultimately trigger device restarts. This type of vulnerability aligns with CWE-129, which describes issues related to insufficient input validation, and represents a classic example of a buffer over-read or improper state handling condition. The flaw operates at the protocol inspection layer where the ASA device processes and analyzes traffic flows, making it particularly dangerous as it can be triggered without authentication or privileged access.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise network security posture and availability. When an ASA device reloads due to this vulnerability, all active security policies and connections are lost, requiring network administrators to manually restore configurations and re-establish security controls. This creates windows of vulnerability during which network traffic may bypass security measures, and the device becomes unavailable to protect against other threats. Organizations relying on these devices for perimeter security face significant risk of unauthorized access or denial of service attacks that could be used as part of larger compromise campaigns. The vulnerability also aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and represents a critical weakness in network infrastructure security that can be exploited by threat actors seeking to disrupt operations.
Mitigation strategies should prioritize immediate software updates to the patched versions specified in Cisco's security advisories, specifically targeting the software versions mentioned in the vulnerability description. Network administrators should also implement additional monitoring and alerting for unusual traffic patterns that might indicate exploitation attempts, while considering network segmentation to limit the potential impact of successful attacks. The vulnerability highlights the importance of maintaining current security patches and demonstrates how protocol inspection mechanisms, while essential for security, can themselves become attack vectors if not properly validated. Organizations should also consider implementing intrusion detection systems that can identify and block malformed MSN traffic patterns, and establish incident response procedures for handling device reload events that may indicate active exploitation attempts.