CVE-2011-1625 in IOS
Summary
by MITRE
Cisco IOS 12.2, 12.3, 12.4, 15.0, and 15.1, when the data-link switching (DLSw) feature is configured, allows remote attackers to cause a denial of service (device crash) by sending a sequence of malformed packets and leveraging a "narrow timing window," aka Bug ID CSCtf74999, a different vulnerability than CVE-2007-0199, CVE-2008-1152, and CVE-2009-0629.
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Analysis
by VulDB Data Team • 03/30/2017
The vulnerability identified as CVE-2011-1625 represents a critical denial of service flaw within Cisco IOS operating systems affecting versions 12.2, 12.3, 12.4, 15.0, and 15.1. This weakness specifically manifests when the data-link switching feature is enabled on affected devices, creating a pathway for remote attackers to intentionally crash network infrastructure. The vulnerability operates through a narrow timing window that significantly reduces the window of opportunity for exploitation, making it both challenging to detect and potentially more difficult to defend against compared to broader attack vectors. This issue is catalogued under Bug ID CSCtf74999 and distinctly separates itself from previously identified vulnerabilities such as CVE-2007-0199, CVE-2008-1152, and CVE-2009-0629, establishing its unique characteristics within the Cisco IOS security landscape.
The technical flaw exploits the DLSw feature implementation within Cisco IOS by sending carefully crafted malformed packets that trigger memory corruption or buffer overflow conditions within the switching module. The narrow timing window aspect suggests that attackers must synchronize their packet transmission precisely to exploit the vulnerability, indicating a sophisticated attack vector that requires specific conditions to be met. This timing sensitivity implies that the vulnerability may be related to race conditions or specific state transitions within the DLSw processing logic where the system fails to properly validate packet sequences or handle unexpected packet structures. The attack mechanism likely involves manipulating packet headers or payload data in a way that causes the device to enter an unstable state, ultimately leading to a complete system crash and service disruption.
The operational impact of this vulnerability extends beyond simple network interruption, as it can result in complete device downtime that affects critical network infrastructure. Organizations relying on Cisco IOS devices with DLSw enabled face potential service degradation or complete network outages, particularly in environments where these devices serve as core routing or switching points. The remote nature of the attack means that adversaries can exploit this vulnerability from outside the network perimeter, potentially allowing for large-scale disruption across multiple affected devices simultaneously. This vulnerability directly impacts the availability aspect of the CIA triad, potentially compromising business continuity and network reliability for organizations that depend on these network devices for critical operations.
Mitigation strategies for CVE-2011-1625 should prioritize immediate patch deployment from Cisco, specifically addressing the identified DLSw implementation flaws in affected IOS versions. Network administrators should consider disabling the DLSw feature entirely on affected devices if the functionality is not mission-critical, as this provides an immediate defense against exploitation. Implementing network segmentation and access controls can help limit the attack surface by restricting unauthorized access to devices that may be vulnerable. Monitoring network traffic for anomalous packet sequences and implementing intrusion detection systems can aid in early detection of exploitation attempts. Organizations should also review their network architecture to ensure that DLSw is only enabled on devices where absolutely necessary, following the principle of least privilege. The vulnerability aligns with CWE-121, which addresses stack-based buffer overflow conditions, and may relate to ATT&CK technique T1499.001 for network denial of service attacks, emphasizing the need for robust network defense mechanisms and proactive vulnerability management strategies.