CVE-2001-0573 in AIX
Summary
by MITRE
lsfs in AIX 4.x allows a local user to gain additional privileges by creating Trojan horse programs named (1) grep or (2) lslv in a certain directory that is under the user s control, which cause lsfs to access the programs in that directory.
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Analysis
by VulDB Data Team • 12/15/2024
The vulnerability described in CVE-2001-0573 represents a privilege escalation issue within the lsfs command on AIX 4.x operating systems. This flaw exploits the trust relationship between system utilities and user-controlled directories, creating a pathway for local attackers to elevate their privileges. The vulnerability specifically targets the lsfs command which is used to display filesystem information in AIX environments, making it a critical component for system administrators and users who need to monitor storage configurations. The issue stems from the command's improper handling of PATH environment variables and executable file resolution, particularly when encountering programs with common names in user-controlled directories. This behavior aligns with CWE-426, which addresses the insecure execution of external programs due to insufficient input validation and PATH manipulation.
The technical exploitation mechanism relies on the principle of executable path resolution where the lsfs command searches for helper programs in the user's PATH without proper validation of the executable's origin or integrity. When a user creates a malicious Trojan horse program named grep or lslv in a directory they control, and that directory appears earlier in the PATH than the system's legitimate executables, the lsfs command will execute the malicious version instead of the intended system utility. This occurs because lsfs does not perform proper validation to ensure that the programs it executes are from trusted system locations rather than user-controlled directories. The vulnerability essentially creates a race condition between legitimate system operations and malicious program execution, where the attacker's program is executed with elevated privileges due to the command's execution context. This type of attack falls under the ATT&CK technique T1068, which involves exploiting legitimate credentials and system access to escalate privileges.
The operational impact of this vulnerability is significant for AIX systems running version 4.x, as it allows local users to potentially gain root privileges or access to sensitive system resources. The attack requires only local access and basic knowledge of the system's PATH structure, making it particularly dangerous in multi-user environments where users may have varying levels of access. System administrators who rely on lsfs for filesystem monitoring and management could unknowingly execute malicious code that could compromise system integrity, potentially leading to unauthorized data access, system modification, or complete system takeover. The vulnerability affects the fundamental security assumptions of the operating system's privilege model, as it bypasses the normal protection mechanisms that should prevent local users from escalating their privileges through command execution. This issue particularly impacts enterprise environments where AIX systems are used for critical operations and where maintaining proper privilege separation is essential for security compliance.
Mitigation strategies for CVE-2001-0573 should focus on addressing the PATH resolution vulnerability and implementing proper privilege control mechanisms. System administrators should immediately update to patched versions of AIX 4.x or apply the relevant security patches provided by IBM. Additionally, administrators should review and tighten the PATH environment variables for system commands to ensure that user-controlled directories do not appear before system directories. Implementing proper file system permissions and using absolute paths for system commands can help prevent the execution of malicious programs. The use of security monitoring tools to detect unauthorized executable creation in system directories can provide early warning of potential exploitation attempts. Organizations should also consider implementing privilege separation techniques and regular security audits to identify and remediate similar vulnerabilities in other system utilities. This vulnerability highlights the importance of maintaining secure coding practices and proper input validation in system-level commands, aligning with security best practices outlined in the NIST SP 800-125 standard for secure system development. The vulnerability also demonstrates the critical need for regular security assessments and prompt patch management to prevent exploitation of known privilege escalation vectors in legacy systems.