CVE-2001-0195 in SSH
Summary
by MITRE
sash before 3.4-4 in Debian GNU/Linux does not properly clone /etc/shadow, which makes it world-readable and could allow local users to gain privileges via password cracking.
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Analysis
by VulDB Data Team • 07/19/2019
The vulnerability described in CVE-2001-0195 represents a critical security flaw in the sash package version 3.4-4 and earlier within Debian GNU/Linux distributions. This issue stems from improper handling of the /etc/shadow file during the cloning process, which fundamentally compromises the security posture of the affected systems. The sash package serves as a secure shell utility that provides authentication and access control mechanisms, making its vulnerability particularly dangerous for system integrity and privilege escalation.
The technical root cause of this vulnerability lies in the inadequate file permission handling during the cloning operation of the /etc/shadow file. The /etc/shadow file contains critical password hash information for all user accounts on the system, and its proper protection is essential for maintaining system security. When sash fails to properly clone this file, it inadvertently creates a world-readable version that should remain restricted to root access only. This misconfiguration allows local users to access sensitive password information that would normally be protected by strict file permissions.
From an operational impact perspective, this vulnerability creates a significant attack vector for local users who wish to escalate their privileges within the system. The ability to read the /etc/shadow file enables attackers to perform password cracking attacks against the collected hash information, potentially leading to unauthorized system access and privilege elevation. This represents a direct violation of the principle of least privilege and undermines the fundamental security model of Unix-like systems where sensitive authentication data should remain protected from unauthorized access.
The vulnerability aligns with CWE-732: Incorrect Permission Assignment for Critical Resource, which specifically addresses the scenario where critical system resources receive incorrect permissions that allow unauthorized access. This weakness directly enables privilege escalation attacks and represents a classic example of insufficient access control mechanisms. The ATT&CK framework categorizes this vulnerability under privilege escalation techniques, specifically T1068: Exploitation for Privilege Escalation, where adversaries leverage system weaknesses to gain elevated privileges.
Mitigation strategies for this vulnerability require immediate system updates to sash package versions that properly handle the /etc/shadow file permissions. System administrators should ensure that all Debian systems are updated to version 3.4-4 or later, which includes the necessary fixes for proper file cloning and permission handling. Additionally, security monitoring should verify that the /etc/shadow file maintains appropriate permissions with root ownership and restricted access. Regular security audits should confirm that no unauthorized modifications to critical system files have occurred, and that proper file permission controls are maintained throughout the system infrastructure.