CVE-2002-1715 in SSH
Summary
by MITRE
SSH 1 through 3, and possibly other versions, allows local users to bypass restricted shells such as rbash or rksh by uploading a script to a world-writeable directory, then executing that script to gain normal shell access.
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Analysis
by VulDB Data Team • 09/02/2025
The vulnerability described in CVE-2002-1715 represents a critical privilege escalation flaw affecting Secure Shell implementations from version 1 through 3, with potential impacts extending to other versions within the same family. This security weakness specifically targets the interaction between SSH's authentication mechanisms and local shell restrictions, creating a pathway for malicious users to circumvent intended security controls. The flaw exploits the fundamental trust model between SSH clients and servers, particularly when dealing with restricted shell environments that are designed to limit user capabilities for security purposes.
The technical implementation of this vulnerability stems from how SSH handles script execution within restricted shell contexts. When users connect via SSH to a system running a restricted shell such as rbash or rksh, the system typically limits their command execution capabilities to prevent unauthorized access to sensitive system resources. However, the vulnerability allows local attackers to upload executable scripts to world-writable directories, which are typically accessible to all users on the system. These scripts can then be executed by the restricted shell environment, effectively bypassing the intended limitations and providing the attacker with full shell privileges. This occurs because the restricted shell does not properly validate or sanitize script execution paths, particularly when scripts are located in directories with permissive access controls.
The operational impact of this vulnerability is significant for system administrators and security practitioners who rely on restricted shell environments as a security control mechanism. Organizations using SSH with rbash or rksh configurations for user access are particularly vulnerable, as attackers can easily escalate privileges without requiring additional authentication credentials or exploiting other system weaknesses. The vulnerability affects not only the immediate security posture but also undermines the principle of least privilege that is fundamental to secure system design. This flaw essentially renders the restricted shell protection mechanisms ineffective, potentially allowing attackers to gain unauthorized access to system resources, modify critical files, or establish persistent access to compromised systems.
Mitigation strategies for this vulnerability should focus on both immediate remediation and long-term architectural improvements. System administrators should ensure that world-writable directories are properly configured with appropriate access controls, limiting write permissions to authorized users only. The SSH configuration should be reviewed to disable or restrict script execution capabilities within restricted shell environments. Implementing proper file system permissions, regular security audits, and monitoring for unauthorized script uploads can help detect and prevent exploitation attempts. Additionally, organizations should consider upgrading to more recent SSH implementations that have addressed this specific vulnerability, as newer versions typically include enhanced security controls and better handling of restricted shell environments. This vulnerability aligns with CWE-276, which addresses improper permissions for critical resources, and maps to ATT&CK technique T1068, which covers local privilege escalation through improper access control mechanisms. The flaw demonstrates the importance of comprehensive security testing that includes evaluation of how different security controls interact with each other rather than relying on single points of defense.