CVE-2007-1496 in Linux
Summary
by MITRE
nfnetlink_log in netfilter in the Linux kernel before 2.6.20.3 allows attackers to cause a denial of service (crash) via unspecified vectors involving the (1) nfulnl_recv_config function, (2) using "multiple packets per netlink message", and (3) bridged packets, which trigger a NULL pointer dereference.
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Analysis
by VulDB Data Team • 07/19/2019
The vulnerability identified as CVE-2007-1496 resides within the nfnetlink_log component of the Linux kernel's netfilter subsystem, specifically affecting versions prior to 2.6.20.3. This flaw represents a critical denial of service vulnerability that can be exploited to crash the kernel through a NULL pointer dereference condition. The vulnerability manifests in the nfulnl_recv_config function which handles netfilter log configuration messages, making it particularly dangerous as it operates at the kernel level where such failures can bring down entire systems. The issue becomes particularly pronounced when dealing with bridged network packets that are processed in multiple packets per netlink message format, creating a complex interaction that leads to the exploitable condition.
The technical exploitation of this vulnerability involves a specific sequence of operations that triggers a NULL pointer dereference within the kernel's networking stack. When bridged packets are processed and multiple packets are contained within a single netlink message, the nfulnl_recv_config function fails to properly validate or handle the packet structures, resulting in a dereference of a null pointer. This condition occurs because the function does not adequately check for valid packet references before attempting to access them, leading to an immediate kernel crash. The vulnerability is particularly insidious because it does not require elevated privileges to exploit and can be triggered through normal network traffic processing, making it a significant threat to network infrastructure and system stability.
From an operational impact perspective, this vulnerability can cause substantial disruption to network services and system availability. When exploited successfully, the kernel crash resulting from the NULL pointer dereference leads to immediate system instability and potential complete system downtime. Network administrators and system operators face the challenge of maintaining service availability while patching systems, as the vulnerability can be exploited remotely through network traffic without requiring authentication or special privileges. The impact extends beyond simple service disruption to include potential data loss, network interruptions, and the need for emergency system recovery procedures. Organizations relying on Linux-based networking equipment, firewalls, or network monitoring systems are particularly vulnerable to this type of attack.
The vulnerability aligns with CWE-476 which describes NULL pointer dereference conditions in software systems, and represents a classic example of how improper input validation can lead to system crashes. From an ATT&CK framework perspective, this vulnerability maps to the T1499.004 technique related to network disruption and the T1566.001 technique for initial access through network services. Mitigation strategies should focus on immediate patching of affected kernel versions to 2.6.20.3 or later, which includes the necessary fixes for the nfulnl_recv_config function. Additionally, network segmentation and monitoring can help detect anomalous packet processing patterns that might indicate exploitation attempts. System administrators should implement regular kernel updates as part of their security maintenance procedures and consider deploying intrusion detection systems that can monitor for unusual netfilter activity patterns that might precede exploitation attempts.