CVE-2013-1243 in Intrusion Prevention System
Summary
by MITRE
The IP stack in Cisco Intrusion Prevention System (IPS) Software in ASA 5500-X IPS-SSP software and hardware modules before 7.1(5)E4, IPS 4500 sensors before 7.1(6)E4, and IPS 4300 sensors before 7.1(5)E4 allows remote attackers to cause a denial of service (MainApp process hang) via malformed IPv4 packets, aka Bug ID CSCtx18596.
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Analysis
by VulDB Data Team • 05/18/2021
The vulnerability identified as CVE-2013-1243 represents a critical denial of service flaw within Cisco's Intrusion Prevention System software ecosystem. This weakness specifically affects the IP stack implementation in Cisco's ASA 5500-X series security appliances, targeting both the IPS-SSP software modules and hardware components. The vulnerability manifests when these systems encounter malformed IPv4 packets, leading to a complete system hang of the MainApp process that governs the core functionality of the intrusion prevention capabilities. The affected versions include ASA 5500-X IPS-SSP software prior to 7.1(5)E4, IPS 4500 sensors before 7.1(6)E4, and IPS 4300 sensors before 7.1(5)E4, indicating a widespread impact across multiple product lines within Cisco's security portfolio.
The technical exploitation of this vulnerability occurs through the careful construction of malformed IPv4 packets that trigger a processing error within the IP stack's packet handling mechanisms. When these specially crafted packets reach the affected Cisco IPS modules, they cause the MainApp process to enter an unrecoverable state, effectively halting all intrusion prevention functionality. This process hang represents a fundamental failure in the system's ability to handle malformed input data, which violates standard security principles of robustness and fault tolerance. The vulnerability operates at the network protocol level, specifically targeting the IPv4 packet processing routines that are essential for the IPS to function properly, making it particularly dangerous as it directly impacts the security appliance's primary operational capability.
The operational impact of CVE-2013-1243 extends far beyond simple service disruption, as it fundamentally compromises the security posture of organizations relying on affected Cisco IPS systems. When the MainApp process hangs, the entire intrusion prevention system becomes non-functional, leaving networks vulnerable to attacks that the IPS would normally detect and block. This creates a dangerous security gap where malicious actors can exploit network traffic patterns without any detection, potentially leading to data breaches, unauthorized access, or other security incidents. The vulnerability's remote exploitability means that attackers do not require physical access or network credentials to trigger the denial of service condition, making it particularly attractive for attackers seeking to disrupt security operations. The potential for cascading failures exists as the system may not automatically recover from the hang condition, requiring manual intervention or system restarts that can take considerable time to implement in production environments.
Organizations affected by this vulnerability should prioritize immediate remediation through the application of Cisco's security patches and software updates. The recommended approach involves upgrading to the patched versions of the affected software releases, specifically targeting the minimum required versions that contain the necessary fixes for the IP stack processing errors. Network administrators should also implement network segmentation and monitoring to detect unusual traffic patterns that might indicate exploitation attempts. From a cybersecurity framework perspective, this vulnerability aligns with CWE-129, which addresses improper validation of input boundaries, and represents a classic example of how malformed input can lead to system instability. The attack surface for this vulnerability can be mapped to ATT&CK technique T1499.004, specifically targeting network denial of service through exploitation of system vulnerabilities, making it a significant concern for organizations implementing the MITRE ATT&CK framework for threat analysis and defense planning.