CVE-2000-1009 in NetBSD
Summary
by MITRE
dump in Red Hat Linux 6.2 trusts the pathname specified by the RSH environmental variable, which allows local users to obtain root privileges by modifying the RSH variable to point to a Trojan horse program.
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Analysis
by VulDB Data Team • 11/24/2024
The vulnerability described in CVE-2000-1009 represents a classic privilege escalation flaw affecting Red Hat Linux 6.2 systems. This issue stems from the improper handling of environment variables within the dump utility, which is commonly used for backing up filesystems. The dump program, designed to create backups of filesystems, was configured to trust the RSH environmental variable without proper validation or sanitization, creating a dangerous attack vector for local users.
The technical flaw resides in the dump utility's insecure handling of the RSH environment variable, which is typically used to specify the remote shell command for network-based operations. When the dump utility executes, it directly uses the value of RSH without implementing proper input validation or path resolution checks. This behavior creates a path traversal vulnerability where an attacker can manipulate the RSH variable to point to a malicious Trojan horse program that has been placed in a location accessible to the dump process. The vulnerability is particularly dangerous because it allows local users to escalate their privileges to root level, bypassing normal access controls and system security measures.
The operational impact of this vulnerability is severe as it provides local attackers with a straightforward method to gain root privileges without requiring any special authentication or network access. The attack requires only local system access and the ability to modify environment variables, making it particularly dangerous in multi-user environments where users might have legitimate access to the system but should not possess root-level capabilities. Once an attacker modifies the RSH variable to point to a crafted malicious program, the dump utility will execute this program with root privileges, effectively granting the attacker complete system control. This vulnerability undermines the fundamental security principle of least privilege and can lead to complete system compromise.
The flaw aligns with CWE-276, which describes improper privileges, and demonstrates how insecure environment variable handling can lead to privilege escalation. From an ATT&CK perspective, this vulnerability maps to privilege escalation techniques where adversaries leverage insecure program execution paths to gain elevated system access. The vulnerability also relates to CWE-78, which addresses command injection issues, as the dump utility essentially executes commands based on untrusted environment variable values. Mitigation strategies should include immediate patching of the dump utility, implementation of environment variable validation, and system hardening measures that restrict modification of critical environment variables. Additionally, system administrators should implement proper access controls and monitor for unauthorized changes to system utilities and environment variables, as this vulnerability can be exploited without any network exposure or external attack surface.