CVE-2018-0467 in IOS
Summary
by MITRE
A vulnerability in the IPv6 processing code of Cisco IOS and IOS XE Software could allow an unauthenticated, remote attacker to cause the device to reload. The vulnerability is due to incorrect handling of specific IPv6 hop-by-hop options. An attacker could exploit this vulnerability by sending a malicious IPv6 packet to or through the affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a denial of service (DoS) condition on an affected device.
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Analysis
by VulDB Data Team • 05/22/2023
The vulnerability identified as CVE-2018-0467 represents a critical flaw in the IPv6 processing implementation of Cisco IOS and IOS XE software versions. This issue stems from inadequate handling of specific IPv6 hop-by-hop options within the network operating system's packet processing logic. The flaw exists at the protocol stack level where the software fails to properly validate and process certain IPv6 extension headers, particularly those that are designed to be processed by every node along the packet's path. Such hop-by-hop options are integral to IPv6 functionality, enabling features like routing headers, fragmentation headers, and other control mechanisms that must be carefully managed during packet forwarding operations.
The technical exploitation of this vulnerability occurs through the transmission of specially crafted IPv6 packets that contain malformed or improperly formatted hop-by-hop options. When the affected Cisco device receives such packets, its processing code encounters an unexpected condition that triggers an improper memory handling routine or stack manipulation. This flaw falls under the CWE-129 weakness category, specifically related to improper validation of input data, and can be mapped to ATT&CK technique T1499.002 which addresses network denial of service attacks. The vulnerability does not require authentication credentials or elevated privileges to exploit, making it particularly dangerous as any remote attacker with network access can potentially trigger the device reload condition. The processing error typically manifests as a memory corruption issue or an unhandled exception that causes the device's routing process to terminate unexpectedly.
The operational impact of CVE-2018-0467 extends beyond simple service disruption, as the device reload process can result in complete network outage for the affected system. During the reload operation, the device temporarily becomes unavailable to process network traffic, leading to extended periods of service unavailability that can affect critical network infrastructure. The vulnerability affects a broad range of Cisco IOS and IOS XE software versions, including various releases of the IOS XE operating system, making it a widespread concern for network administrators managing multiple devices. Network infrastructure that relies heavily on IPv6 connectivity faces the highest risk, particularly in environments where devices may be exposed to untrusted network traffic or where IPv6 is enabled for various network services.
Mitigation strategies for this vulnerability require immediate implementation of security patches provided by Cisco through their security advisory process. The recommended approach involves applying the appropriate software updates that contain corrected IPv6 processing logic and enhanced validation routines for hop-by-hop options. Network administrators should also implement access control measures to limit IPv6 traffic to only trusted sources, utilizing firewall rules and access control lists to filter malicious packets at network boundaries. Additionally, monitoring and logging capabilities should be enhanced to detect unusual patterns of IPv6 packet processing that may indicate exploitation attempts. Organizations should conduct regular vulnerability assessments to identify other potential weaknesses in their network infrastructure and ensure that all network devices are running patched software versions. The implementation of network segmentation strategies can help limit the scope of potential exploitation and provide additional defense-in-depth measures against similar vulnerabilities.