CVE-2006-6656 in NetBSD
Summary
by MITRE
Unspecified vulnerability in ptrace in NetBSD-current before 20061027, NetBSD 3.0 and 3.0.1 before 20061027, and NetBSD 2.x before 20061119 allows local users to read kernel memory and obtain sensitive information via certain manipulations of a PT_LWPINFO request, which leads to a memory leak and information leak.
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Analysis
by VulDB Data Team • 08/12/2018
This vulnerability resides within the ptrace system call implementation of NetBSD operating systems, specifically affecting versions prior to certain patch dates in 2006. The flaw manifests in the handling of PT_LWPINFO requests, which are used by debuggers and tracing utilities to gather information about specific threads within a process. This represents a critical security weakness that allows local attackers with minimal privileges to exploit kernel memory access mechanisms and extract sensitive information from system memory. The vulnerability is classified under CWE-200 as it involves improper information exposure, and relates to CWE-122 which deals with insufficient synchronization in memory management operations. The root cause stems from inadequate validation and handling of memory references during ptrace operations, creating a pathway for unauthorized memory access.
The technical exploitation occurs when a local user crafts specific PT_LWPINFO requests that manipulate the kernel's memory management structures. This manipulation results in a memory leak condition where kernel memory addresses become accessible to user-space processes without proper authorization. The vulnerability essentially bypasses normal kernel memory protection mechanisms by exploiting a flaw in the ptrace subsystem's request processing logic. Attackers can leverage this to read arbitrary kernel memory locations, potentially obtaining sensitive data such as passwords, encryption keys, or other confidential information stored in kernel memory. This type of information disclosure vulnerability is particularly dangerous because it can provide attackers with the means to escalate privileges or discover additional system vulnerabilities. The attack vector aligns with ATT&CK technique T1059.003 for command and scripting interpreter usage, and T1003.001 for credential dumping through system memory access.
The operational impact of this vulnerability extends beyond simple information disclosure, as it creates a foundation for more sophisticated attacks within the compromised system. Local users who exploit this vulnerability can potentially access kernel memory spaces that contain critical system information, including cryptographic keys used for system authentication, network credentials, and other sensitive operational data. This weakness undermines the fundamental security model of the operating system by allowing unauthorized memory access that should be strictly protected. The vulnerability affects multiple NetBSD releases including 2.x series and versions 3.0 and 3.0.1, making it a widespread issue across several system versions. System administrators and security professionals must understand that this vulnerability can be exploited to gain insights into system internals, potentially enabling further attacks such as privilege escalation or targeted exploitation of other system components. The memory leak aspect of this vulnerability compounds the risk by creating persistent exposure conditions that could be exploited repeatedly over time.
Mitigation strategies for this vulnerability require immediate patching of affected NetBSD systems to the versions released after the specified dates mentioned in the CVE. System administrators should prioritize updating all NetBSD installations to ensure proper kernel memory protection mechanisms are in place. Additional protective measures include implementing strict process monitoring to detect unusual ptrace activity, employing kernel security modules to restrict memory access permissions, and conducting regular security audits to identify potential exploitation attempts. Organizations should also consider implementing network segmentation and access controls to limit local user privileges where possible, reducing the attack surface for this type of vulnerability. The fix addresses the core issue by strengthening input validation for ptrace requests and implementing proper memory access controls during PT_LWPINFO processing. Security teams should monitor for any attempts to exploit this vulnerability through log analysis and intrusion detection systems, as the memory access patterns may be detectable through careful monitoring of system calls. This vulnerability demonstrates the importance of maintaining up-to-date system patches and the critical nature of kernel security mechanisms in preventing unauthorized memory access.