CVE-2011-3280 in IOS
Summary
by MITRE
Memory leak in the NAT implementation in Cisco IOS 12.1 through 12.4 and 15.0 through 15.1, and IOS XE 3.1.xSG, allows remote attackers to cause a denial of service (memory consumption or device reload) by sending crafted SIP packets to UDP port 5060, aka Bug ID CSCtj04672.
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Analysis
by VulDB Data Team • 11/23/2021
The vulnerability described in CVE-2011-3280 represents a critical memory leak issue within Cisco IOS network operating systems affecting versions 12.1 through 12.4 and 15.0 through 15.1, as well as IOS XE 3.1.xSG releases. This flaw specifically targets the Network Address Translation implementation within the routing and switching software, creating a significant security risk that can be exploited remotely. The vulnerability manifests when the system processes specially crafted Session Initiation Protocol packets transmitted to UDP port 5060, which is the standard port used for SIP communications in VoIP environments. This particular attack vector leverages the underlying NAT functionality to consume system resources in an uncontrolled manner, ultimately leading to system instability.
The technical root cause of this memory leak stems from insufficient input validation and resource management within the SIP processing module of Cisco IOS. When the system receives malformed or crafted SIP packets, the NAT implementation fails to properly handle the memory allocation and deallocation processes required for maintaining session state information. This deficiency creates a gradual accumulation of memory fragments that cannot be properly reclaimed by the system's garbage collection mechanisms, resulting in progressive memory consumption. The vulnerability is classified under CWE-401 as a weakness related to improper management of memory allocation, specifically addressing the failure to properly free dynamically allocated memory resources. The flaw operates at the network protocol processing layer, where the system's handling of SIP traffic through NAT translates into an exploitable condition that can be triggered remotely without requiring authentication credentials.
The operational impact of this vulnerability extends beyond simple resource exhaustion to potentially cause complete system failure through device reloads or unresponsive states. Attackers can maintain sustained exploitation by continuously sending crafted SIP packets, gradually consuming available memory until the system reaches critical thresholds. This type of denial of service attack directly impacts the availability of network services, particularly affecting VoIP infrastructure that relies on SIP communications for call establishment and management. The attack scenario aligns with ATT&CK technique T1499.004 which describes network denial of service attacks, specifically targeting network infrastructure to disrupt service availability. Organizations using affected Cisco IOS versions may experience service interruptions, call failures, and potential complete device unavailability, particularly in environments where SIP-based communications are critical for business operations.
Mitigation strategies for this vulnerability require immediate implementation of network access controls and system updates to address the underlying memory management issues. Cisco released security advisories and patches to resolve this issue, recommending that affected organizations apply the appropriate software updates as soon as possible. Network administrators should implement access control lists to filter traffic on UDP port 5060, particularly from untrusted sources, and consider deploying intrusion prevention systems that can detect and block malformed SIP packets. The vulnerability demonstrates the importance of proper input validation and resource management in network infrastructure software, highlighting how seemingly minor implementation flaws can create significant security risks. Additionally, organizations should implement monitoring solutions to detect unusual memory consumption patterns that could indicate exploitation attempts, as the gradual nature of memory leaks makes them particularly difficult to detect through traditional security scanning methods.