CVE-2008-1058 in OpenBSD
Summary
by MITRE
The tcp_respond function in netinet/tcp_subr.c in OpenBSD 4.1 and 4.2 allows attackers to cause a denial of service (panic) via crafted TCP packets. NOTE: some of these details are obtained from third party information.
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Analysis
by VulDB Data Team • 09/19/2018
The vulnerability identified as CVE-2008-1058 represents a critical denial of service flaw within the OpenBSD operating system's network stack implementation. This issue resides in the tcp_respond function located in the netinet/tcp_subr.c source file, affecting OpenBSD versions 4.1 and 4.2. The flaw manifests when the system processes crafted TCP packets that exploit a specific condition in the TCP response handling mechanism, leading to a kernel panic that completely crashes the affected system. Such vulnerabilities are particularly dangerous in networked environments where attackers can remotely trigger system failures without requiring authentication or elevated privileges.
The technical root cause of this vulnerability stems from insufficient input validation within the tcp_respond function's packet processing logic. When malformed TCP packets are received, the function fails to properly handle certain edge cases in the TCP header structure, particularly around sequence number and acknowledgment number fields. This improper validation allows attackers to craft packets that, when processed by the kernel's TCP subsystem, trigger an unexpected state within the kernel memory management system. The vulnerability is classified under CWE-129 as an insufficient input validation issue, where the system fails to properly validate the bounds of input data before processing it. The flaw represents a classic example of an unchecked buffer access or improper state handling that can lead to system-wide crashes.
The operational impact of CVE-2008-1058 is severe and directly affects system availability within OpenBSD environments. An attacker capable of sending crafted TCP packets to a vulnerable system can induce a kernel panic, causing the entire system to crash and requiring manual reboot to restore functionality. This creates a significant denial of service condition that can be exploited remotely, making it particularly dangerous for network services, web servers, and any systems that process incoming TCP traffic. The vulnerability affects systems that are actively listening for TCP connections, including but not limited to web servers, mail servers, and database servers. From an attacker's perspective, this represents a low-effort, high-impact method for disrupting services, as the attack requires only basic network packet crafting capabilities and does not demand specialized tools or privileged access. The vulnerability also aligns with ATT&CK technique T1499.004 for network denial of service attacks, specifically targeting the availability aspect of the CIA triad.
Mitigation strategies for this vulnerability focus on immediate system updates and network-level protections. The most effective solution involves applying the official OpenBSD security patches released for versions 4.1 and 4.2, which correct the input validation logic in the tcp_respond function to properly handle malformed TCP packets. System administrators should also implement network-level filtering to drop suspicious TCP packets at the perimeter, particularly those with malformed TCP headers or unusual sequence number patterns. Additionally, deploying intrusion detection systems that can identify and alert on suspicious TCP traffic patterns may help detect exploitation attempts. Organizations should consider implementing rate limiting on incoming TCP connections and monitoring for unusual system behavior that might indicate a panic condition. The vulnerability serves as a reminder of the critical importance of input validation in kernel space code and demonstrates how seemingly minor flaws in network protocol handling can result in complete system compromise. Regular security updates and patch management procedures become essential defensive measures against such vulnerabilities.