CVE-2014-3271 in IOS XE
Summary
by MITRE
The DHCPv6 implementation in Cisco IOS XR allows remote attackers to cause a denial of service (device crash) via a malformed packet, aka Bug IDs CSCum85558, CSCum20949, CSCul61849, and CSCul71149.
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Analysis
by VulDB Data Team • 06/20/2021
The vulnerability described in CVE-2014-3271 represents a critical denial of service flaw within Cisco IOS XR systems that specifically targets the DHCPv6 implementation. This issue affects network infrastructure devices running Cisco IOS XR software, which are commonly deployed in service provider environments and enterprise networks where reliable routing and switching services are essential. The vulnerability manifests when the system receives malformed DHCPv6 packets, causing the device to crash and potentially disrupting network services for extended periods.
The technical root cause of this vulnerability lies in insufficient input validation within the DHCPv6 processing code of Cisco IOS XR. When a malicious actor sends carefully crafted malformed packets to a vulnerable device, the system fails to properly handle the unexpected data structure, leading to memory corruption and subsequent system instability. This type of vulnerability falls under CWE-129, which describes improper validation of input boundaries, and specifically relates to improper handling of malformed network protocol data. The flaw demonstrates a classic buffer over-read or memory corruption issue where the device does not adequately validate packet headers and payload contents before processing them through the DHCPv6 service.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise network availability and reliability in production environments. Network administrators may experience unexpected device crashes during normal operations, leading to service interruptions that could affect multiple network segments depending on the role of the compromised device. In service provider environments, this vulnerability could result in widespread outages affecting customer connectivity and business operations. The attack vector requires only remote access to send malformed packets to the target device, making it particularly dangerous as it can be exploited from outside the network perimeter without requiring physical access or elevated privileges.
Mitigation strategies for this vulnerability should include immediate software patching from Cisco, as the company released specific fixes addressing the DHCPv6 processing flaws. Network administrators should implement network segmentation and access control measures to limit exposure to potentially malicious traffic, including configuring firewall rules to restrict DHCPv6 traffic from untrusted sources. Additionally, monitoring and logging mechanisms should be enhanced to detect unusual DHCPv6 traffic patterns that might indicate exploitation attempts. The vulnerability aligns with ATT&CK technique T1499.002, which covers network denial of service attacks, and represents a significant concern for organizations following the NIST Cybersecurity Framework where maintaining system availability and resilience is paramount. Organizations should also consider implementing intrusion detection systems that can identify and alert on malformed DHCPv6 packets to provide early warning of potential exploitation attempts.