CVE-2012-5415 in ASA
Summary
by MITRE
Race condition on Cisco Adaptive Security Appliances (ASA) devices allows remote attackers to cause a denial of service (CPU consumption or device reload) by establishing multiple connections, leading to improper handling of hash lookups for secondary flows, aka Bug IDs CSCue31622 and CSCuc71272.
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Analysis
by VulDB Data Team • 04/27/2017
The vulnerability identified as CVE-2012-5415 represents a critical race condition flaw within Cisco Adaptive Security Appliances that fundamentally undermines the device's ability to maintain stable network operations. This issue specifically affects ASA devices running software versions prior to 9.1.2 and 8.4.5, where the operating system fails to properly synchronize access to hash tables during concurrent connection establishment processes. The flaw manifests when multiple connections are simultaneously initiated against the device, creating a scenario where the system's hash lookup mechanisms become overwhelmed and begin to consume excessive CPU resources.
The technical implementation of this vulnerability stems from improper synchronization mechanisms within the ASA's connection handling code, particularly during the processing of secondary flows that occur after initial connection establishment. When numerous connections are initiated concurrently, the device's hash table management system experiences a race condition where multiple threads attempt to access and modify the same hash buckets simultaneously without proper locking mechanisms. This results in a cascading effect where the system's CPU utilization spikes dramatically, often reaching 100% usage levels, effectively rendering the device incapable of processing legitimate network traffic. The vulnerability is classified under CWE-362, which specifically addresses race conditions in software implementations where concurrent access to shared resources leads to unpredictable behavior.
From an operational perspective, this vulnerability poses significant risks to network availability and business continuity, as remote attackers can exploit it to perform denial of service attacks against ASA devices without requiring authentication or privileged access. The impact extends beyond simple service disruption, as the excessive CPU consumption can trigger automatic device reload mechanisms, leading to complete service outages that may last several minutes while the system recovers. Network administrators face the challenge of identifying and mitigating these attacks, as they typically appear as legitimate connection patterns rather than obvious malicious traffic. The vulnerability's exploitation aligns with ATT&CK technique T1498, which describes denial of service attacks targeting network infrastructure components, and can be leveraged as part of broader attack campaigns to compromise network availability.
The mitigation strategies for CVE-2012-5415 primarily focus on implementing software updates and configuration hardening measures. Cisco has released patches addressing this vulnerability in ASA software versions 9.1.2 and 8.4.5, which include improved synchronization mechanisms for hash table access and enhanced connection handling routines. Network administrators should prioritize applying these patches to all affected devices, particularly those handling high volumes of concurrent connections. Additionally, implementing connection rate limiting policies and monitoring for unusual connection patterns can help detect and prevent exploitation attempts. The configuration of proper access control lists and limiting the number of concurrent connections per source IP address provides an additional layer of defense. Organizations should also consider implementing network segmentation and deploying intrusion detection systems to monitor for potential exploitation attempts, as the vulnerability can be used as a stepping stone for more sophisticated attacks targeting the broader network infrastructure.