CVE-2007-4567 in Linux
Summary
by MITRE
The ipv6_hop_jumbo function in net/ipv6/exthdrs.c in the Linux kernel before 2.6.22 does not properly validate the hop-by-hop IPv6 extended header, which allows remote attackers to cause a denial of service (NULL pointer dereference and kernel panic) via a crafted IPv6 packet.
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Analysis
by VulDB Data Team • 12/19/2024
The vulnerability described in CVE-2007-4567 represents a critical flaw in the Linux kernel's handling of IPv6 hop-by-hop extended headers, specifically within the ipv6_hop_jumbo function located in net/ipv6/exthdrs.c. This issue affects Linux kernel versions prior to 2.6.22 and demonstrates a classic case of improper input validation that can lead to system instability. The vulnerability operates at the network protocol level where the kernel fails to adequately validate the structure and contents of IPv6 hop-by-hop headers, creating an exploitable condition that remote attackers can leverage to disrupt system operations.
The technical flaw stems from a missing validation check within the ipv6_hop_jumbo function that processes IPv6 hop-by-hop headers containing jumbo payload options. When a maliciously crafted IPv6 packet containing a specially formatted hop-by-hop header is received, the kernel's processing logic attempts to dereference a NULL pointer without proper bounds checking or header validation. This occurs because the function assumes certain header fields contain valid data while failing to verify that the header structure adheres to IPv6 specification requirements. The vulnerability specifically targets the jumbo payload option within hop-by-hop headers, which is designed to allow IPv6 packets larger than the standard 65535 byte limit to be transmitted across networks.
The operational impact of this vulnerability is severe as it can be exploited to cause immediate system disruption through denial of service attacks. Remote attackers can construct IPv6 packets with malformed hop-by-hop headers that trigger a NULL pointer dereference in kernel space, ultimately leading to a kernel panic and system crash. This type of vulnerability represents a fundamental security weakness that allows unauthenticated remote attackers to compromise system availability without requiring any privileged access or authentication credentials. The attack vector is particularly concerning because IPv6 traffic can be transmitted over public networks, making the vulnerability exploitable from any location on the internet.
From a cybersecurity perspective, this vulnerability aligns with CWE-125, which describes "Out-of-bounds Read" conditions where programs access memory locations outside the bounds of allocated buffers, and it also relates to CWE-476, "NULL Pointer Dereference" as the primary mechanism of exploitation. The vulnerability maps to ATT&CK technique T1499.001, "Endpoint Denial of Service" which involves causing systems to become unavailable through various methods including kernel-level exploits. The impact extends beyond simple service disruption as kernel panics can lead to complete system shutdowns, data loss, and potential compromise of other network services running on the affected system.
Mitigation strategies for this vulnerability involve immediate kernel upgrades to versions 2.6.22 or later where the validation logic has been corrected to properly check hop-by-hop header structures before processing jumbo payload options. System administrators should also implement network-level filtering to block IPv6 packets with malformed hop-by-hop headers when such traffic is not required for legitimate network operations. Additionally, monitoring for unusual network traffic patterns or kernel panic events can help detect exploitation attempts, while maintaining updated security patches and conducting regular vulnerability assessments ensures continued protection against similar issues in the kernel's network stack implementation.