CVE-2002-2180 in OpenBSD
Summary
by MITRE
The setitimer(2) system call in OpenBSD 2.0 through 3.1 does not properly check certain arguments, which allows local users to write to kernel memory and possibly gain root privileges, possibly via an integer signedness error.
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Analysis
by VulDB Data Team • 07/11/2024
The vulnerability identified as CVE-2002-2180 represents a critical kernel-level flaw in OpenBSD operating systems ranging from version 2.0 through 3.1. This issue stems from improper argument validation within the setitimer system call implementation, which serves as a fundamental mechanism for managing interval timers in Unix-like systems. The flaw manifests as a failure to properly validate input parameters, creating a pathway for malicious code execution within kernel space. Such vulnerabilities are particularly dangerous because they can be exploited by local users who already have system access, potentially escalating their privileges to the root level. The vulnerability specifically involves an integer signedness error that allows attackers to manipulate memory addresses through crafted timer parameters, bypassing normal kernel security boundaries.
The technical implementation of this vulnerability demonstrates a classic case of improper input validation within kernel code, which aligns with CWE-20 - Improper Input Validation. The setitimer system call accepts various timer structures that include interval and value parameters which are not adequately checked for valid ranges or signedness constraints. When these parameters are processed without proper bounds checking, attackers can craft malicious inputs that cause the kernel to write to arbitrary memory locations. This type of memory corruption vulnerability can be leveraged to execute arbitrary code with kernel privileges, effectively compromising the entire system. The vulnerability's exploitation requires local access but can result in complete system compromise, making it particularly concerning for multi-user environments.
The operational impact of CVE-2002-2180 extends beyond simple privilege escalation, as it represents a fundamental breakdown in kernel memory protection mechanisms. Attackers exploiting this vulnerability can potentially execute code with the highest system privileges, allowing them to modify system files, install backdoors, or extract sensitive information from the kernel memory space. This vulnerability falls under the ATT&CK technique T1068 - Exploitation for Privilege Escalation, where attackers leverage system call vulnerabilities to gain elevated privileges. The impact is particularly severe because the vulnerability exists in core system functionality that many applications rely upon, meaning that exploitation could occur through legitimate system usage patterns. The integer signedness error creates a predictable attack vector where specific parameter values can trigger the memory corruption behavior.
Mitigation strategies for this vulnerability require immediate system updates to patched versions of OpenBSD where the argument validation has been corrected. System administrators should prioritize patching all affected OpenBSD systems to prevent exploitation attempts, as the vulnerability is well-documented and exploitable. Additional defensive measures include implementing strict system call filtering using mechanisms like seccomp-bpf or similar sandboxing techniques to restrict access to potentially problematic system calls. Monitoring for unusual system call patterns or attempts to manipulate timer structures should be implemented as part of security operations. The vulnerability also highlights the importance of thorough code review processes for kernel components, particularly around input validation and memory management. Organizations should ensure their systems maintain up-to-date security patches and conduct regular vulnerability assessments to identify similar issues in other kernel components. This vulnerability demonstrates the critical need for proper integer handling in kernel space and serves as a reminder that even fundamental system calls can contain exploitable flaws when proper validation is omitted.