CVE-2011-4012 in IOS
Summary
by MITRE
Cisco IOS 12.0, 15.0, and 15.1, when a Policy Feature Card 3C (PFC3C) is used, does not create a fragment entry during processing of an ICMPv6 ACL, which has unspecified impact and remote attack vectors, aka Bug ID CSCtj90091.
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Analysis
by VulDB Data Team • 05/09/2018
The vulnerability described in CVE-2011-4012 affects Cisco IOS versions 12.0, 15.0, and 15.1 when operating with a Policy Feature Card 3C (PFC3C) hardware component. This issue represents a critical flaw in the handling of ICMPv6 access control list processing within the router's packet filtering mechanisms. The vulnerability specifically manifests when the system fails to properly create a fragment entry during ICMPv6 ACL processing, creating an unexpected behavior that could be exploited by remote attackers.
The technical flaw stems from an incomplete implementation of the Internet Control Message Protocol version 6 (ICMPv6) access control list handling within the Cisco IOS operating system. When an ICMPv6 packet is processed through an access control list on a device equipped with PFC3C, the system does not properly maintain fragment entry information during the processing cycle. This failure creates a potential denial of service condition where legitimate traffic may be disrupted or improperly handled. The vulnerability is particularly concerning because it operates at the network layer where ICMPv6 traffic flows through access control lists, potentially allowing attackers to craft specific packets that could trigger the flawed behavior.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it represents a potential attack vector that could be leveraged by remote adversaries to disrupt network operations. The unspecified nature of the impact suggests that the flaw could potentially be exploited in multiple ways, including but not limited to service disruption, traffic manipulation, or even potential privilege escalation scenarios. Network administrators must understand that this vulnerability could be exploited without requiring local access or authentication credentials, making it particularly dangerous in environments where remote access to network infrastructure is possible.
From a cybersecurity perspective, this vulnerability aligns with CWE-119, which deals with improper restriction of operations within a limited context, and represents a failure in proper memory management during packet processing. The ATT&CK framework would classify this as a Network Service Scanning technique, as attackers could potentially use this vulnerability to probe network infrastructure for specific configurations. The vulnerability also relates to the privilege escalation category in ATT&CK, as it could potentially allow attackers to gain unauthorized access to network devices through manipulation of network protocols. Organizations should consider implementing network segmentation and monitoring solutions to detect anomalous ICMPv6 traffic patterns that could indicate exploitation attempts.
Mitigation strategies should include immediate deployment of Cisco's security advisories and patches, which address the specific fragment entry handling issue in the PFC3C module. Network administrators should also implement additional monitoring of ICMPv6 traffic patterns and consider disabling unnecessary ICMPv6 functionality on affected devices until proper patches are applied. The vulnerability highlights the importance of thorough testing of network security features, particularly when hardware modules like PFC3C are involved in packet processing. Organizations should also consider implementing network access controls that limit which systems can send ICMPv6 traffic to critical network infrastructure, reducing the attack surface for this particular vulnerability.