CVE-2007-0343 in OpenBSD
Summary
by MITRE
OpenBSD before 20070116 allows remote attackers to cause a denial of service (infinite loop and CPU consumption) via certain IPv6 ICMP (aka ICMP6) echo request packets.
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Analysis
by VulDB Data Team • 12/22/2016
The vulnerability described in CVE-2007-0343 represents a critical denial of service flaw affecting OpenBSD systems prior to the 20070116 release. This issue specifically targets the IPv6 implementation within the OpenBSD kernel, where maliciously crafted ICMP6 echo request packets can trigger an infinite loop condition that consumes excessive CPU resources. The flaw demonstrates how network protocol implementations can contain logical errors that, when exploited remotely, can effectively瘫痪 entire systems by exhausting computational resources. Such vulnerabilities are particularly dangerous in network infrastructure devices that serve as routers, firewalls, or other critical connectivity points where sustained resource exhaustion can impact network availability for legitimate users.
The technical root cause of this vulnerability lies in the improper handling of certain IPv6 ICMP echo request packets within the OpenBSD kernel's network stack implementation. When processing these specific ICMP6 packets, the kernel enters an infinite loop during packet processing, causing continuous CPU utilization that can reach 100% and prevent the system from performing other essential functions. This behavior aligns with CWE-835, which categorizes infinite loops as a common programming error that can lead to denial of service conditions. The vulnerability is particularly insidious because it requires no authentication or special privileges from the attacker, making it a straightforward remote exploitation vector that can be triggered from anywhere on the internet.
From an operational perspective, this vulnerability presents significant risk to OpenBSD deployments that handle IPv6 traffic, particularly in environments where network availability is critical. The infinite loop condition causes sustained high CPU usage that can render systems unresponsive to legitimate network traffic, effectively creating a denial of service condition. Attackers can exploit this by sending carefully crafted ICMP6 echo requests to target systems, causing the affected systems to become non-responsive while consuming all available CPU cycles. The impact extends beyond individual system compromise to potentially affect entire network segments if multiple devices are vulnerable, as the resource exhaustion can cascade through network infrastructure components. This vulnerability also demonstrates the importance of proper input validation and defensive programming practices in kernel space code, as the flaw occurs during routine network protocol processing rather than in specialized or privileged operations.
The mitigation strategy for this vulnerability involves applying the security patch released by OpenBSD on January 16, 2007, which addresses the specific infinite loop condition in the IPv6 ICMP6 handling code. Organizations should prioritize updating their OpenBSD systems to versions released after this date, as the patch corrects the logical error that causes the infinite loop during ICMP6 packet processing. System administrators should also consider implementing network access controls and firewall rules that can filter or rate-limit ICMP6 traffic to reduce the impact of potential exploitation attempts, though this represents a temporary workaround rather than a permanent fix. The vulnerability serves as a reminder of the importance of regular security updates and the critical nature of kernel-level vulnerabilities that can affect system availability and network integrity. This issue is categorized under ATT&CK technique T1499.004, which covers network denial of service attacks, highlighting how such vulnerabilities can be leveraged to compromise system availability and network operations.