CVE-2011-3275 in IOS XE
Summary
by MITRE
Memory leak in Cisco IOS 12.4, 15.0, and 15.1, and IOS XE 2.5.x through 3.2.x, allows remote attackers to cause a denial of service (memory consumption) via a crafted SIP message, aka Bug ID CSCti48504.
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Analysis
by VulDB Data Team • 11/23/2021
This vulnerability represents a critical memory leak flaw in Cisco IOS software versions 12.4, 15.0, and 15.1, as well as IOS XE versions 2.5.x through 3.2.x, which can be exploited remotely to cause denial of service conditions through crafted SIP (Session Initiation Protocol) messages. The issue stems from improper handling of SIP protocol messages within the Cisco IOS implementation, specifically when processing malformed or specially crafted SIP requests that trigger memory allocation without subsequent deallocation. The vulnerability is catalogued under CWE-401 as a weakness related to improper management of memory resources, where the system fails to properly release allocated memory blocks after processing SIP transactions, leading to progressive memory consumption over time.
The technical exploitation of this vulnerability occurs when a remote attacker sends a specially crafted SIP message to a vulnerable Cisco device that is configured to process SIP traffic. The device's IOS software processes this malformed message and allocates memory resources to handle the SIP transaction, but due to flawed memory management logic, these allocated memory segments are not properly freed when the processing completes. This results in a gradual accumulation of memory usage that eventually leads to memory exhaustion, causing the device to become unresponsive or crash entirely, thereby creating a denial of service condition that disrupts legitimate network services. The attack vector is particularly concerning as it requires no authentication and can be executed remotely, making it highly accessible to threat actors.
The operational impact of this vulnerability extends beyond simple service disruption, as it affects critical network infrastructure components that rely on SIP for voice and video communication services. Network administrators may experience unexpected device restarts, service interruptions for VoIP communications, and potential cascading failures in network operations if multiple devices are affected simultaneously. The memory leak progression means that the impact may not be immediately apparent, allowing attackers to maintain persistent disruption over extended periods without detection. This vulnerability specifically targets SIP processing capabilities within Cisco's network operating system, making it particularly dangerous for enterprises that depend heavily on SIP-based communication systems for their business operations.
Mitigation strategies for this vulnerability involve implementing immediate software updates and patches provided by Cisco to address the memory management flaw in the affected IOS versions. Network administrators should also consider implementing SIP message filtering and rate limiting mechanisms to reduce the impact of potentially malicious SIP traffic, while monitoring memory usage patterns for early detection of exploitation attempts. The ATT&CK framework categorizes this vulnerability under the T1499.004 technique for network denial of service, where adversaries leverage software flaws to consume system resources. Additionally, implementing network segmentation to isolate SIP processing components and deploying intrusion detection systems that can identify anomalous SIP traffic patterns provides additional layers of defense against exploitation attempts. Organizations should also conduct regular vulnerability assessments to identify other potential memory management issues in their network infrastructure components.