CVE-2012-4576 in FreeBSD
Summary
by MITRE
FreeBSD: Input Validation Flaw allows local users to gain elevated privileges
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Analysis
by VulDB Data Team • 03/05/2024
The vulnerability identified as CVE-2012-4576 represents a critical input validation flaw within the FreeBSD operating system that enables local attackers to escalate their privileges from standard user level to root access. This weakness resides in the kernel's handling of certain input parameters, specifically within the system call interface that governs privilege escalation mechanisms. The flaw stems from insufficient validation of user-supplied data during critical kernel operations, creating a pathway for malicious code execution that bypasses standard security controls. Attackers exploiting this vulnerability can manipulate kernel functions through crafted input sequences that are not properly sanitized or validated before processing.
The technical implementation of this vulnerability involves a classic buffer overread condition combined with improper input sanitization within the FreeBSD kernel's privilege management subsystem. When legitimate system calls are processed, the kernel fails to adequately validate the length and content of user-provided parameters, allowing attackers to inject malformed data that can manipulate kernel memory structures. This particular flaw aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which addresses heap-based buffer overflow scenarios. The vulnerability manifests when the kernel processes certain ioctl commands or system calls that accept user-space buffers without proper boundary checking, enabling attackers to overwrite critical kernel memory locations.
The operational impact of CVE-2012-4576 extends beyond simple privilege escalation as it fundamentally undermines the security model of the FreeBSD operating system. Local attackers who can execute code on a target system gain immediate access to the highest privilege levels, allowing them to modify system files, install malicious software, establish backdoors, or completely compromise the system's integrity. This vulnerability affects all versions of FreeBSD that were released prior to the patch release addressing this specific issue. The exploitation requires only local access to the system, making it particularly dangerous in multi-user environments where users might not be properly trusted. The vulnerability can be leveraged to bypass security measures such as file permissions, access controls, and audit logging mechanisms that normally protect sensitive system resources.
Mitigation strategies for this vulnerability focus on immediate patch deployment and system hardening measures. The primary solution involves applying the official FreeBSD security patches that address the input validation issues in the kernel's privilege handling code. System administrators should prioritize updating all affected FreeBSD systems to the latest stable releases that contain the necessary fixes. Additional defensive measures include implementing strict user access controls, monitoring system logs for suspicious privilege escalation attempts, and employing kernel hardening techniques such as stack canaries and address space layout randomization. From an adversarial perspective, this vulnerability aligns with ATT&CK technique T1068, which describes local privilege escalation through kernel exploits, and T1548.001, covering abuse of system permissions. Organizations should also consider implementing intrusion detection systems that can identify exploitation attempts and maintain comprehensive backup and recovery procedures to address potential compromise scenarios resulting from successful exploitation of this vulnerability.