CVE-2007-6762 in Linux
Summary
by MITRE
In the Linux kernel before 2.6.20, there is an off-by-one bug in net/netlabel/netlabel_cipso_v4.c where it is possible to overflow the doi_def->tags[] array.
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Analysis
by VulDB Data Team • 11/13/2023
The vulnerability identified as CVE-2007-6762 represents a critical buffer overflow flaw within the Linux kernel's NetLabel implementation, specifically affecting versions prior to 2.6.20. This issue resides in the netlabel_cipso_v4.c file where the CIPSO (Common IP Security Option) protocol handling contains an off-by-one error that can lead to memory corruption. The vulnerability manifests when processing CIPSO protocol options, which are used for implementing mandatory access control policies in network communications. The flaw occurs in the doi_def->tags[] array management where the boundary checking is insufficient, allowing attackers to write beyond the allocated array bounds.
The technical nature of this vulnerability stems from improper input validation within the kernel's network security module. When processing incoming network packets containing CIPSO options, the kernel fails to properly validate the number of tags being processed against the allocated array size. This off-by-one error creates a condition where an attacker can manipulate the CIPSO option data to cause a buffer overflow, potentially leading to arbitrary code execution or system crashes. The vulnerability is particularly dangerous because it operates within kernel space, meaning successful exploitation could result in complete system compromise. The flaw aligns with CWE-121, which describes heap-based buffer overflow conditions, and represents a classic example of insufficient boundary checking in memory management operations.
The operational impact of CVE-2007-6762 extends beyond simple denial of service scenarios, as the vulnerability can be exploited to achieve privilege escalation and remote code execution. Attackers can craft malicious network packets containing specially formatted CIPSO options that trigger the buffer overflow when processed by the kernel's network stack. This creates a significant risk for systems running vulnerable kernel versions, particularly those serving as network gateways or security appliances where CIPSO protocol support is enabled. The vulnerability is classified under the ATT&CK technique T1068, which covers 'Exploitation for Privilege Escalation', as successful exploitation can lead to elevated system privileges. Systems with network access and CIPSO protocol support enabled are particularly at risk, as the attack surface expands to include any network interface that processes incoming packets with CIPSO options.
Mitigation strategies for this vulnerability primarily focus on kernel version updates and network access controls. The most effective solution involves upgrading to Linux kernel version 2.6.20 or later, where the buffer overflow has been corrected through proper boundary checking implementation. System administrators should also implement network segmentation and access controls to limit exposure, particularly disabling CIPSO protocol support on systems where it is not strictly required. Additional protective measures include monitoring network traffic for malformed CIPSO options and implementing intrusion detection systems that can identify suspicious packet patterns. The vulnerability demonstrates the critical importance of proper input validation in kernel space operations and highlights the necessity of thorough security testing for network protocol implementations. Organizations should conduct vulnerability assessments to identify systems running affected kernel versions and prioritize patch deployment to prevent exploitation.