CVE-2005-2872 in Linux
Summary
by MITRE
The ipt_recent kernel module (ipt_recent.c) in Linux kernel before 2.6.12, when running on 64-bit processors such as AMD64, allows remote attackers to cause a denial of service (kernel panic) via certain attacks such as SSH brute force, which leads to memset calls using a length based on the u_int32_t type, acting on an array of unsigned long elements, a different vulnerability than CVE-2005-2873.
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Analysis
by VulDB Data Team • 03/12/2021
The vulnerability described in CVE-2005-2872 represents a critical memory management flaw within the Linux kernel's iptables framework, specifically affecting the ipt_recent module that tracks recently seen IP addresses for firewall rules. This issue manifests in kernels prior to version 2.6.12 and exclusively impacts 64-bit architectures including AMD64 processors. The vulnerability stems from a fundamental type mismatch in memory allocation calculations where the module employs u_int32_t length parameters to govern memset operations on arrays of unsigned long elements, creating a scenario where memory boundaries are improperly calculated and accessed.
The technical exploitation of this vulnerability occurs through carefully crafted network traffic that triggers the ipt_recent module's processing of incoming packets. During normal operation, this module maintains lists of IP addresses that have recently communicated with the system, typically used for implementing rate limiting or access control policies. When subjected to specific attack patterns such as SSH brute force attempts, the module's internal memory management routines become compromised due to the arithmetic error between 32-bit and 64-bit data types. The memset function receives a length parameter that is calculated based on u_int32_t values, but when applied to arrays of unsigned long elements on 64-bit systems, this creates a situation where the memory access exceeds allocated boundaries, resulting in kernel memory corruption.
The operational impact of this vulnerability is severe, as it can be leveraged by remote attackers to induce kernel panics and complete system crashes without requiring any local privileges or authentication. This makes the vulnerability particularly dangerous in networked environments where systems are exposed to external traffic. The denial of service condition effectively renders the affected system unusable until manual reboot occurs, potentially creating significant downtime for critical infrastructure. The vulnerability is classified under CWE-129 as an insufficient input validation, specifically involving improper handling of data type conversions between different architectural contexts. This flaw demonstrates how seemingly minor type conversion issues in kernel space can lead to catastrophic system failures, highlighting the importance of rigorous memory management practices in operating system components.
From an adversarial perspective, this vulnerability aligns with ATT&CK technique T1499.004, which involves network denial of service attacks, and represents a classic example of how kernel-level vulnerabilities can be exploited for system disruption. The attack vector requires only network connectivity to the target system, making it particularly attractive to threat actors seeking to disrupt services. The vulnerability's exploitation pattern is consistent with the broader category of buffer overflows and memory corruption issues that have historically plagued operating system kernels. Systems running affected kernel versions are particularly vulnerable when they implement iptables rules that utilize the ipt_recent module, making proper patch management crucial for maintaining system availability and security posture. The flaw specifically affects 64-bit systems due to the architectural differences in how data types are handled, emphasizing the importance of architecture-specific testing and validation in security assessments.
Mitigation strategies for CVE-2005-2872 include immediate patching of affected kernel versions to 2.6.12 or later, which resolves the type conversion issue in the ipt_recent module. Organizations should also consider disabling the ipt_recent module if it is not actively required for firewall policies, as this eliminates the attack surface entirely. Network administrators should implement monitoring for unusual traffic patterns that might indicate exploitation attempts, particularly around SSH and other commonly targeted services. Additionally, maintaining up-to-date kernel versions and regularly reviewing firewall rule configurations helps prevent exploitation of similar vulnerabilities. The vulnerability serves as a reminder of the critical importance of thorough testing across different architectural platforms and the necessity of maintaining robust kernel security practices to prevent memory corruption issues that can lead to complete system compromise.