CVE-2006-6418 in Tru64
Summary
by MITRE
Buffer overflow in the POSIX Threads library (libpthread) on HP Tru64 UNIX 4.0F PK8, 4.0G PK4, and 5.1A PK6 allows local users to gain root privileges via a long PTHREAD_CONFIG environment variable.
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Analysis
by VulDB Data Team • 08/10/2018
The vulnerability described in CVE-2006-6418 represents a critical buffer overflow condition within the POSIX Threads library implementation on HP Tru64 UNIX operating systems. This flaw specifically affects versions 4.0F PK8, 4.0G PK4, and 5.1A PK6 of the HP Tru64 UNIX platform, where the libpthread library fails to properly validate the length of the PTHREAD_CONFIG environment variable. The issue stems from inadequate bounds checking during the processing of thread configuration parameters, creating an exploitable condition that can be leveraged by local attackers to escalate privileges to root level access. The vulnerability is particularly concerning because it operates at the system library level, meaning any application or process that utilizes pthread functionality could potentially be exploited through manipulation of this environment variable.
The technical implementation of this buffer overflow occurs when the libpthread library processes the PTHREAD_CONFIG environment variable without proper input validation or length constraints. When an attacker provides an excessively long value for this environment variable, the library's internal buffer allocation mechanism fails to handle the overflow gracefully, resulting in memory corruption that can be exploited to overwrite critical system data structures or execution control information. This type of vulnerability falls under CWE-121, which specifically addresses stack-based buffer overflow conditions, and more broadly aligns with CWE-787, representing out-of-bounds write vulnerabilities. The exploitation mechanism relies on the attacker's ability to control the execution flow of the targeted process by overwriting return addresses or other critical program state information within the memory layout.
The operational impact of CVE-2006-6418 extends beyond simple privilege escalation to encompass potential system compromise and unauthorized access to sensitive data. Since the vulnerability affects a core system library that is utilized by numerous applications and system processes, a successful exploitation could provide attackers with root privileges across the entire system without requiring additional attack vectors or complex exploitation techniques. The local nature of this vulnerability means that an attacker must already have access to the system, but once exploited, the consequences are severe as the attacker gains complete administrative control. This vulnerability directly maps to ATT&CK technique T1068, which covers 'Exploitation for Privilege Escalation', and T1548.001, which addresses 'Abuse of Sudo Rights', since the privilege escalation occurs through system-level library manipulation rather than through direct user privilege abuse.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term security hardening measures. The primary recommendation involves applying the official HP patches and updates that specifically address the buffer overflow condition in the libpthread library implementation. System administrators should also implement environment variable restrictions and monitoring to detect unusual or potentially malicious values being set for PTHREAD_CONFIG. Additional defensive measures include implementing proper input validation at the application level, using address space layout randomization techniques, and maintaining strict access controls to prevent unauthorized local access. Organizations should also conduct comprehensive vulnerability assessments to identify any other applications or services that might be susceptible to similar buffer overflow conditions in their HP Tru64 UNIX environments. The vulnerability highlights the importance of proper bounds checking in system libraries and demonstrates how low-level implementation flaws can have significant security implications across the entire operating system.