CVE-2013-3463 in ASA
Summary
by MITRE
The protocol-inspection feature on Cisco Adaptive Security Appliances (ASA) devices does not properly implement the idle timeout, which allows remote attackers to cause a denial of service (connection-table exhaustion) via crafted requests that use an inspected protocol, aka Bug ID CSCuh13899.
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Analysis
by VulDB Data Team • 12/26/2024
The vulnerability identified as CVE-2013-3463 affects Cisco Adaptive Security Appliances (ASA) devices and represents a critical flaw in the protocol-inspection feature implementation. This issue specifically targets the idle timeout mechanism within the ASA's connection handling system, creating a condition where remote attackers can exploit the device's connection table management. The vulnerability stems from improper handling of idle connection timeouts when processing inspected protocols, leading to a scenario where legitimate network traffic is disrupted through resource exhaustion. The flaw impacts the fundamental operational integrity of ASA devices by allowing malicious actors to consume available connection table entries without proper cleanup, ultimately resulting in denial of service conditions.
The technical implementation of this vulnerability resides in the ASA's connection table management subsystem where the idle timeout feature fails to properly clean up inspected connections that remain inactive for extended periods. When protocol inspection is enabled for specific traffic flows, the device maintains connection entries in its table to track session state information. However, the flawed idle timeout implementation does not correctly identify when these entries should be removed from the table, causing them to persist indefinitely or for extended periods beyond normal operational requirements. This improper state management creates a resource leak condition where the connection table gradually fills with stale entries, eventually exhausting available capacity and preventing legitimate connections from being established.
From an operational perspective, this vulnerability presents a significant risk to network availability and service continuity. Attackers can exploit this weakness by sending crafted requests that utilize inspected protocols, maintaining these connections in a state that triggers the idle timeout bug. The resulting connection table exhaustion forces the ASA device to either drop legitimate connections or become unresponsive to new connection attempts. This denial of service condition can severely impact network accessibility and business operations, particularly in environments where ASA devices serve as primary security gateways for enterprise networks or critical infrastructure. The vulnerability is particularly dangerous because it can be exploited remotely without requiring authentication, making it accessible to any attacker with network access to the affected device.
The impact of this vulnerability aligns with CWE-400, which addresses "Uncontrolled Resource Consumption" in software systems, specifically highlighting the improper management of connection resources within network security appliances. From an ATT&CK framework perspective, this vulnerability maps to the T1499.004 technique related to "Endpoint Denial of Service" and represents a network-level attack vector that can be executed without direct system compromise. Organizations should implement immediate mitigations including applying the latest Cisco security patches, configuring tighter connection table limits, and implementing network segmentation to isolate vulnerable ASA devices. Additionally, monitoring for unusual connection table usage patterns and implementing intrusion detection systems can help identify exploitation attempts. The vulnerability underscores the critical importance of proper resource management in security appliances and demonstrates how seemingly minor implementation flaws can create significant operational risks in network infrastructure devices.