CVE-2002-0701 in OpenBSD
Summary
by MITRE
ktrace in BSD-based operating systems allows the owner of a process with special privileges to trace the process after its privileges have been lowered, which may allow the owner to obtain sensitive information that the process obtained while it was running with the extra privileges.
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Analysis
by VulDB Data Team • 02/11/2017
The vulnerability described in CVE-2002-0701 affects ktrace functionality in BSD-based operating systems, representing a significant privilege escalation and information disclosure risk. This flaw exists in the kernel tracing mechanism that is designed to monitor system calls and other kernel activities for debugging and security analysis purposes. The vulnerability specifically targets processes that have undergone privilege reduction, where a process initially runs with elevated privileges but then lowers them for security reasons. The ktrace subsystem fails to properly enforce access controls when tracing such processes, creating a potential attack vector for malicious actors who control the process owner.
The technical implementation of this vulnerability stems from improper privilege checking within the ktrace system call handling code. When a process with special privileges executes and subsequently lowers its privileges, the ktrace facility should prevent unauthorized tracing operations that could expose sensitive information obtained during the elevated privilege execution. However, the flaw allows the process owner to maintain tracing capabilities even after privilege reduction, effectively bypassing the intended security controls. This occurs because the kernel does not properly validate whether the tracing operation should be permitted based on the current privilege level of the target process, creating a persistent access path that can be exploited to extract confidential data.
The operational impact of this vulnerability extends beyond simple information disclosure to encompass potential privilege escalation scenarios. An attacker who controls a process owner can leverage this flaw to access sensitive data that the process encountered while operating with elevated privileges, including but not limited to authentication tokens, cryptographic keys, system credentials, and confidential application data. This vulnerability particularly affects systems where processes are designed to drop privileges after initialization, such as daemon processes, system services, or any application that follows privilege separation security models. The implications are severe because the information obtained through this technique could enable further attacks, including lateral movement, credential compromise, or complete system takeover.
Security professionals should consider this vulnerability in relation to the broader ATT&CK framework, specifically under the techniques related to privilege escalation and credential access. The vulnerability aligns with CWE-284, which addresses improper access control, and CWE-276, which deals with incorrect default permissions. Mitigation strategies should include immediate patching of affected BSD systems, implementing proper privilege separation controls, and monitoring for unauthorized ktrace operations. System administrators should also consider implementing additional security measures such as restricting ktrace access to specific user groups, employing mandatory access controls, and regularly auditing process tracing activities. The vulnerability demonstrates the critical importance of maintaining proper privilege boundaries in kernel-level operations and highlights the need for comprehensive security testing of system call interfaces that handle sensitive operations.