CVE-2002-0816 in Tru64
Summary
by MITRE
Buffer overflow in su in Tru64 Unix 5.x allows local users to gain root privileges via a long username and argument.
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Analysis
by VulDB Data Team • 10/25/2024
The vulnerability described in CVE-2002-0816 represents a critical buffer overflow flaw within the su command implementation of Tru64 Unix version 5.x operating systems. This issue specifically affects the privilege escalation mechanism that allows local users to elevate their privileges to root level, creating a significant security risk for systems running this particular Unix variant. The vulnerability stems from insufficient input validation within the su command's username handling routine, where the system fails to properly check the length of user-provided input before processing it.
The technical implementation of this buffer overflow occurs when a local attacker provides an excessively long username argument to the su command. The underlying flaw exists in how the system allocates memory for username storage and processing, where fixed-size buffers are used without adequate bounds checking. When the username exceeds the allocated buffer space, adjacent memory locations become overwritten, potentially corrupting critical program state information including return addresses and system variables. This memory corruption can be exploited to redirect program execution flow and ultimately execute arbitrary code with root privileges. The vulnerability is classified as a classic stack-based buffer overflow, which aligns with CWE-121, which describes buffer overflow conditions where insufficient bounds checking allows memory to be overwritten.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with complete system control and access to all resources protected by root-level permissions. Local users who can execute the su command can leverage this flaw to bypass authentication mechanisms and gain unauthorized administrative access to the system. This creates a persistent security risk since the vulnerability exists at the core system utility level, making it particularly dangerous for multi-user environments where local access might be granted to untrusted users. The exploitability of this vulnerability is relatively straightforward, requiring only local system access and the ability to execute the su command with a crafted long argument, making it a preferred target for both malicious insiders and external attackers who have gained local footholds.
Mitigation strategies for CVE-2002-0816 must address both immediate system protection and long-term architectural improvements. The most direct remediation involves applying vendor patches or updates that correct the buffer handling implementation in the su command, ensuring proper bounds checking and input validation. System administrators should also implement strict access controls and monitoring for su command usage, particularly for accounts that may be vulnerable to exploitation. Additional defensive measures include enabling system logging for su command executions, implementing intrusion detection systems to monitor for anomalous privilege escalation attempts, and conducting regular security audits to identify potential local access points. From a broader security perspective, organizations should consider implementing principle of least privilege models, reducing local user access where possible, and employing additional layers of protection such as mandatory access controls or privilege separation mechanisms. The vulnerability also highlights the importance of following secure coding practices and adhering to security standards like those outlined in the CWE database and ATT&CK framework, which emphasize the need for robust input validation and memory management practices to prevent such exploitable conditions.