CVE-2001-1091 in NetBSD
Summary
by MITRE
The (1) dump and (2) dump_lfs commands in NetBSD 1.4.x through 1.5.1 do not properly drop privileges, which could allow local users to gain privileges via the RCMD_CMD environment variable.
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Analysis
by VulDB Data Team • 06/02/2018
The vulnerability described in CVE-2001-1091 represents a critical privilege escalation flaw affecting NetBSD operating systems in versions 1.4.x through 1.5.1. This issue specifically targets two commands within the NetBSD distribution: dump and dump_lfs. These commands are designed for system backup operations and filesystem dumping functionality respectively. The flaw stems from improper privilege management during command execution, creating a pathway for local attackers to elevate their system privileges through manipulation of environment variables.
The technical root cause of this vulnerability lies in the failure of the dump and dump_lfs commands to properly drop elevated privileges after initialization. When these commands execute, they should transition from root privileges to the privileges of the user who invoked them. However, due to implementation errors in the privilege management code, the commands maintain elevated privileges throughout their execution lifecycle. This design flaw allows local users to inject malicious code through the RCMD_CMD environment variable, which is typically used for remote command execution in network backup operations.
The operational impact of this vulnerability is significant as it enables local users to perform privilege escalation attacks without requiring remote access or complex exploitation techniques. Attackers can leverage this vulnerability to gain root access to the system, potentially leading to complete system compromise. The vulnerability affects the core backup functionality of NetBSD systems, making it particularly dangerous for server environments where regular backup operations are performed. The RCMD_CMD environment variable manipulation creates a direct attack vector that bypasses normal privilege boundaries, allowing unprivileged users to execute commands with elevated privileges.
This vulnerability maps directly to CWE-276, which describes improper privileges, and aligns with ATT&CK technique T1068, which covers privilege escalation through exploitation of environment variables. The flaw demonstrates poor secure coding practices in privilege management and environment variable handling. Organizations running affected NetBSD versions should immediately apply patches or updates that properly implement privilege dropping mechanisms for these commands. The recommended mitigation involves ensuring that all backup and filesystem dump commands properly transition from root to user privileges after initialization, and that environment variables are properly sanitized to prevent injection attacks.
The broader implications of this vulnerability highlight the importance of proper privilege management in system utilities and the need for comprehensive security testing of core operating system components. This issue underscores the critical nature of maintaining least privilege principles in system design and the potential consequences of failing to properly implement privilege separation in security-critical applications. Regular security audits of system utilities and careful attention to privilege management implementation are essential to prevent similar vulnerabilities in other software components.