CVE-2001-1398 in Linux
Summary
by MITRE
Masquerading code for Linux kernel before 2.2.19 does not fully check packet lengths in certain cases, which may lead to a vulnerability.
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Analysis
by VulDB Data Team • 06/25/2021
The vulnerability described in CVE-2001-1398 represents a significant security flaw in the Linux kernel version 2.2.18 and earlier, specifically within the network packet handling mechanisms that are governed by the kernel's masquerading code. This code is responsible for network address translation and packet filtering operations that are essential for secure network communication. The vulnerability stems from insufficient validation of packet length parameters during the processing of network traffic, creating a potential vector for exploitation that could allow attackers to manipulate network communications or potentially gain unauthorized access to systems. The masquerading functionality, which is part of the netfilter framework and implements iptables rules, is designed to handle packet forwarding and translation between different network segments. However, in versions prior to 2.2.19, the code fails to properly validate packet boundaries and length constraints, leading to potential buffer overflows or memory corruption scenarios. This issue directly relates to CWE-129, which describes improper validation of length of input buffers, and can be categorized under the broader category of buffer overflow vulnerabilities that have been extensively documented in security literature. The operational impact of this vulnerability extends beyond simple packet processing failures, as it could enable attackers to craft malicious network packets that exploit the inadequate length checking mechanisms. When the kernel processes these malformed packets, the insufficient validation allows for memory corruption that could potentially be leveraged to execute arbitrary code or cause system instability. The vulnerability is particularly concerning because it affects core network functionality that is fundamental to system operation, making it a critical target for exploitation. The attack surface is broad since network traffic is ubiquitous in computing environments, and the vulnerability could be exploited through various network protocols that rely on the masquerading code for packet handling. According to ATT&CK framework category T1071.004, this vulnerability could be exploited to perform protocol manipulation attacks, where adversaries leverage network protocol weaknesses to gain unauthorized access or disrupt services. The specific nature of the flaw involves the kernel's inability to properly validate packet boundaries during network address translation operations, which can lead to memory corruption when packets exceed expected size limits or contain malformed length fields. This type of vulnerability is particularly dangerous because it operates at the kernel level, meaning that successful exploitation could result in complete system compromise without requiring elevated privileges. The vulnerability affects systems that rely on Linux kernel versions prior to 2.2.19 for network address translation, NAT, and packet filtering operations, which were common in many enterprise and server environments during that time period. The risk is amplified by the fact that such systems often handle critical network traffic and may be exposed to untrusted network inputs, making them attractive targets for exploitation. Mitigation strategies for this vulnerability primarily involve upgrading to Linux kernel version 2.2.19 or later, where the packet length validation has been properly implemented and enhanced. System administrators should also consider implementing network segmentation and access controls to limit exposure to potentially malicious network traffic, while monitoring network protocols to detect anomalous packet patterns that might indicate exploitation attempts. Additionally, the vulnerability highlights the importance of proper input validation in kernel space operations and underscores the need for comprehensive security testing of core system components that handle untrusted data. The fix implemented in kernel version 2.2.19 addresses the root cause by strengthening the packet length validation checks within the masquerading code, ensuring that all packet boundaries are properly validated before processing. This improvement aligns with security best practices that emphasize the principle of least privilege and defense in depth, particularly in kernel-level code where input validation is critical for maintaining system integrity and preventing privilege escalation attacks.