CVE-2012-1315 in IOS
Summary
by MITRE
Memory leak in the SIP inspection feature in the Zone-Based Firewall in Cisco IOS 12.4, 15.0, 15.1, and 15.2 allows remote attackers to cause a denial of service (memory consumption or device reload) via crafted transit SIP traffic, aka Bug ID CSCti46171.
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Analysis
by VulDB Data Team • 03/22/2021
The vulnerability described in CVE-2012-1315 represents a critical memory leak flaw within Cisco IOS Zone-Based Firewall implementations that specifically affects SIP (Session Initiation Protocol) inspection functionality. This issue manifests in multiple IOS versions including 12.4, 15.0, 15.1, and 15.2, indicating a widespread exposure across significant portions of Cisco's networking infrastructure. The vulnerability is categorized under CWE-401 as a weakness related to improper handling of memory allocation, which directly impacts system stability and availability. The flaw operates through the Zone-Based Firewall's SIP inspection engine, which is designed to monitor and control SIP traffic passing through network boundaries, making it a critical component for VoIP security implementations.
The technical mechanism behind this vulnerability involves the improper handling of memory allocation during SIP packet processing within the firewall's inspection engine. When crafted SIP traffic traverses the affected Cisco IOS devices, the Zone-Based Firewall fails to properly release allocated memory resources after processing the SIP packets, leading to progressive memory consumption over time. This memory leak occurs during the normal operation of SIP inspection, where legitimate SIP signaling traffic is processed for security purposes but the firewall's memory management routines do not correctly account for and release the allocated resources. The vulnerability is particularly dangerous because it can be triggered remotely without requiring authentication, making it accessible to any attacker who can send SIP traffic to the affected device. The flaw is classified under the ATT&CK technique T1499.004 for Network Denial of Service, specifically targeting network infrastructure components to cause availability disruption.
The operational impact of this vulnerability extends far beyond simple resource exhaustion, as it can lead to complete device unavailability and system reloads that disrupt critical network services. Network administrators may observe gradual performance degradation followed by complete system crashes, forcing unexpected device restarts that can interrupt voice services, video conferencing, and other time-sensitive communications. The memory leak can be particularly devastating in enterprise environments where Cisco IOS devices serve as core network infrastructure components, as these devices often operate continuously and maintain critical network connectivity for business operations. The vulnerability affects organizations that rely on SIP-based communication systems, including unified communications platforms, VoIP gateways, and network security appliances that utilize Cisco's Zone-Based Firewall capabilities. The impact is amplified when considering that SIP traffic often flows through network perimeters and is subject to security inspection, making this vulnerability particularly dangerous for organizations with extensive VoIP deployments.
Mitigation strategies for this vulnerability require immediate attention from network administrators and security teams to protect their infrastructure from potential exploitation. The most effective approach involves applying Cisco's official security patches and updates that address the memory leak in the SIP inspection feature, as outlined in Cisco Security Advisory CSCti46171. Organizations should also implement temporary workarounds such as disabling SIP inspection on affected devices or implementing traffic filtering rules to limit the exposure of the vulnerable feature. Network segmentation and access control measures can help reduce the attack surface by limiting the exposure of affected devices to external SIP traffic. Additionally, monitoring systems should be deployed to track memory usage patterns and detect potential exploitation attempts, as early detection can prevent complete system failures. The vulnerability highlights the importance of maintaining current security patches and implementing comprehensive network monitoring strategies to identify and respond to similar issues before they can be exploited in production environments.