CVE-2005-4618 in Linux
Summary
by MITRE
Buffer overflow in sysctl in the Linux Kernel 2.6 before 2.6.15 allows local users to corrupt user memory and possibly cause a denial of service via a long string, which causes sysctl to write a zero byte outside the buffer. NOTE: since the sysctl is called from a userland program that provides the argument, this might not be a vulnerability, unless a legitimate user-assisted or setuid scenario can be identified.
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Analysis
by VulDB Data Team • 07/07/2021
The vulnerability described in CVE-2005-4618 represents a critical buffer overflow condition within the Linux kernel's sysctl subsystem affecting versions prior to 2.6.15. This flaw manifests when the sysctl function processes user-provided input strings that exceed the allocated buffer boundaries, leading to memory corruption that can potentially compromise system stability and security. The vulnerability specifically occurs when a long string is passed to the sysctl function, causing it to write a zero byte beyond the intended buffer limits, which constitutes a classic buffer overflow scenario. The affected kernel version range indicates this was a significant issue that persisted across multiple releases, highlighting the importance of proper input validation in kernel space operations.
The technical implementation of this vulnerability involves the sysctl system call interface which serves as a mechanism for configuring kernel parameters at runtime through user-space programs. When a user-space application invokes sysctl with an excessively long string argument, the kernel's internal buffer handling fails to properly validate the input length before performing memory operations. This results in the overflow condition where a zero byte is written beyond the allocated memory space, potentially corrupting adjacent memory regions and user data. The vulnerability's nature suggests it operates at the kernel level where memory corruption can have severe implications for system integrity and user data protection.
From an operational perspective, this vulnerability presents a significant risk for local privilege escalation and denial of service conditions. The fact that it requires a legitimate user-assisted scenario or setuid execution context limits its immediate exploitability but does not eliminate the threat entirely. Attackers could potentially leverage this vulnerability through malicious user-space programs that make sysctl calls with crafted long strings, particularly in environments where setuid programs exist or where users have the ability to execute programs with elevated privileges. The potential for denial of service through memory corruption is substantial, as the overflow can cause kernel panics or unpredictable behavior that affects system stability and availability.
The vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and demonstrates the critical importance of proper input validation in kernel space operations. The ATT&CK framework categorizes this under privilege escalation and defense evasion techniques where adversaries can exploit kernel-level vulnerabilities to gain unauthorized access to system resources or disrupt system operations. The vulnerability's classification as a local privilege escalation vector means that even without network access, an attacker with user-level privileges could potentially leverage this flaw to compromise system integrity. Mitigation strategies should focus on kernel version updates, proper input validation, and implementing security controls that monitor for unusual sysctl behavior. System administrators should prioritize patching affected kernel versions and implementing monitoring solutions that can detect abnormal memory access patterns or buffer overflow attempts. The vulnerability serves as a reminder of the critical need for robust input validation and memory safety practices in kernel-level code, particularly when handling user-provided data through system call interfaces that are designed to be accessible from user-space applications.