CVE-2010-4671 in IOS
Summary
by MITRE
The Neighbor Discovery (ND) protocol implementation in the IPv6 stack in Cisco IOS before 15.0(1)XA5 allows remote attackers to cause a denial of service (CPU consumption and device hang) by sending many Router Advertisement (RA) messages with different source addresses, as demonstrated by the flood_router6 program in the thc-ipv6 package, aka Bug ID CSCti33534.
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Analysis
by VulDB Data Team • 10/08/2021
The vulnerability described in CVE-2010-4671 represents a critical flaw in the IPv6 Neighbor Discovery protocol implementation within Cisco IOS operating systems. This issue affects versions prior to 15.0(1)XA5 and demonstrates how improperly handled network protocol messages can lead to significant system degradation. The vulnerability specifically targets the Router Advertisement message processing functionality, which is fundamental to IPv6 network operations and device communication. The flaw enables remote attackers to exploit the protocol implementation through a carefully crafted flood of Router Advertisement messages, each containing distinct source addresses to overwhelm the target device's processing capabilities.
The technical mechanism behind this vulnerability involves the insufficient validation and handling of Router Advertisement messages within the IPv6 stack implementation. When the system receives multiple RA messages with varying source addresses, it fails to properly manage the processing overhead, leading to excessive CPU consumption and eventual device hang conditions. The attack vector specifically leverages the flood_router6 utility from the thc-ipv6 package, which is designed to generate high-volume IPv6 network traffic patterns. This particular attack method exploits the lack of rate limiting or source address validation in the ND protocol handling code, allowing an attacker to consume system resources proportional to the number of unique source addresses in the flood.
From an operational impact perspective, this vulnerability presents a severe threat to network infrastructure stability and availability. Devices running affected Cisco IOS versions become vulnerable to remote denial of service attacks that can render network services unavailable to legitimate users. The CPU consumption patterns associated with this vulnerability can cause complete system hangs, requiring manual intervention and device rebooting to restore normal operations. Network administrators face the challenge of maintaining service availability while dealing with potentially persistent attacks that can be launched from anywhere on the internet, as the vulnerability is remotely exploitable without authentication requirements. The impact extends beyond individual device compromise to potentially affect entire network segments that depend on the compromised devices for routing and connectivity.
The vulnerability maps directly to CWE-400, which addresses unchecked resource consumption, and aligns with ATT&CK technique T1498, specifically focusing on Network Denial of Service. Organizations should implement immediate mitigation strategies including applying the relevant Cisco IOS patches and updates, configuring rate limiting on IPv6 Router Advertisement messages, and deploying network access control measures to restrict potentially malicious traffic. Network segmentation and monitoring systems should be enhanced to detect unusual patterns of Router Advertisement traffic, while baseline performance monitoring should be established to quickly identify when devices begin experiencing resource exhaustion conditions. The implementation of proper source address validation and message rate limiting within the IPv6 stack configuration provides effective protection against this specific attack vector while maintaining legitimate network functionality.