CVE-2009-4920 in ASA 5580
Summary
by MITRE
Unspecified vulnerability in CTM on Cisco Adaptive Security Appliances (ASA) 5580 series devices with software 8.1(2) allows remote attackers to cause a denial of service (watchdog traceback) via a large amount of small-packet data, aka Bug ID CSCsu11412.
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Analysis
by VulDB Data Team • 04/20/2017
The vulnerability identified as CVE-2009-4920 affects Cisco Adaptive Security Appliances (ASA) 5580 series devices running software version 8.1(2) and represents a significant denial of service weakness that can be exploited remotely. This issue manifests through a specific pattern of network traffic that triggers an unexpected system behavior in the device's watchdog mechanism, leading to complete service disruption. The vulnerability is particularly concerning because it does not require authentication or special privileges to exploit, making it accessible to any remote attacker who can send network packets to the affected device.
The technical flaw lies within the packet processing and watchdog subsystem of the ASA 5580 series appliances. When these devices receive a large volume of small packets, the system's internal watchdog timer mechanism becomes overwhelmed and enters an abnormal state that results in a traceback error. This traceback represents a critical failure in the device's fault handling system where the watchdog process cannot properly manage the high-frequency packet processing load. The vulnerability specifically targets the memory management and timer handling components that are responsible for monitoring system stability and detecting potential failures in the network security appliance's operation.
The operational impact of this vulnerability extends beyond simple service interruption to potentially compromise the entire network security infrastructure. When the watchdog traceback occurs, the affected ASA device becomes unresponsive and effectively ceases to function as a security appliance, leaving network traffic unprotected and potentially exposing sensitive systems to unauthorized access. The attack vector requires only the ability to send network packets to the device, making it particularly dangerous in environments where network access cannot be fully controlled or monitored. Network administrators may find their primary security controls suddenly unavailable, creating a window of vulnerability that could be exploited by malicious actors for more sophisticated attacks.
Cisco has documented this vulnerability as Bug ID CSCsu11412 and has provided specific software updates to address the issue in subsequent releases. The recommended mitigation involves immediate deployment of the latest software patches and updates to the affected ASA 5580 series devices. Organizations should also implement network monitoring solutions to detect unusual packet patterns that might indicate exploitation attempts. From a cybersecurity perspective, this vulnerability aligns with attack patterns described in the MITRE ATT&CK framework under the defense evasion and denial of service categories, specifically targeting the availability of network infrastructure components. The weakness also corresponds to CWE-121, which deals with stack-based buffer overflow conditions, though in this case the manifestation is through watchdog timer handling rather than traditional buffer overflow mechanisms. Security teams should consider implementing rate limiting and packet filtering rules as additional protective measures while awaiting official patches to ensure continued network protection during the remediation process.