CVE-2003-0462 in Linux
Summary
by MITRE
A race condition in the way env_start and env_end pointers are initialized in the execve system call and used in fs/proc/base.c on Linux 2.4 allows local users to cause a denial of service (crash).
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 11/06/2024
The vulnerability described in CVE-2003-0462 represents a critical race condition within the Linux kernel's execve system call implementation that specifically affects kernel versions 2.4 and earlier. This flaw manifests in the improper initialization and handling of environment pointer variables during process execution transitions, creating a window where concurrent operations can lead to system instability. The issue occurs in the interaction between the execve system call and the /proc filesystem implementation in fs/proc/base.c, where the env_start and env_end pointers are manipulated without adequate synchronization mechanisms. This race condition exploits the timing dependencies between process creation and environment variable handling, allowing malicious local users to manipulate the kernel's internal state through carefully crafted execution sequences.
The technical exploitation of this vulnerability leverages the inherent timing discrepancies in how the kernel manages environment variable pointers during process execution. When a process executes the execve system call, the kernel must properly initialize the env_start and env_end variables that define the boundaries of the environment block within the process's memory space. The race condition occurs because these pointers are not adequately protected against concurrent access during the transition period between process initialization and execution. Attackers can trigger this condition by creating multiple simultaneous execve operations or by carefully timing their process creation to overlap with existing process execution contexts. The flaw specifically affects the kernel's handling of environment variable memory management in the proc filesystem, where the pointers are used to determine valid memory regions for environment data access.
The operational impact of this vulnerability extends beyond simple denial of service to potentially compromise system stability and availability. Local users with minimal privileges can exploit this race condition to force kernel crashes, leading to system reboots and service interruptions that can affect the entire system. The vulnerability is particularly dangerous in multi-user environments where malicious users can repeatedly trigger the condition to maintain persistent system instability. From a cybersecurity perspective, this represents a privilege escalation vector that, while requiring local access, can be leveraged to create persistent disruptions. The attack surface is significant as execve is one of the most frequently used system calls in Unix-like operating systems, making this vulnerability particularly impactful for system administrators and security professionals who must protect against unauthorized local access.
Mitigation strategies for CVE-2003-0462 focus primarily on kernel updates and system hardening measures that address the underlying race condition. The most effective solution involves upgrading to Linux kernel versions 2.6 or later where the race condition has been properly addressed through improved synchronization mechanisms and memory management procedures. System administrators should implement strict access controls to prevent unauthorized local execution and monitor for unusual execve activity patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-362, which categorizes race conditions in concurrent systems, and can be mapped to ATT&CK technique T1059.003 for execution via command and scripting interpreter, particularly when attackers leverage the system call to trigger kernel-level disruptions. Additional protective measures include implementing kernel hardening patches, disabling unnecessary system calls where possible, and monitoring for memory access violations that might indicate exploitation attempts against the vulnerable kernel implementation.