CVE-2001-0859 in Linux
Summary
by MITRE
2.4.3-12 kernel in Red Hat Linux 7.1 Korean installation program sets the setting default umask for init to 000, which installs files with world-writeable permissions.
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Analysis
by VulDB Data Team • 04/14/2019
The vulnerability described in CVE-2001-0859 represents a critical security flaw in the Linux kernel version 2.4.3-12 distributed with Red Hat Linux 7.1, specifically affecting the Korean installation program's handling of umask settings during system initialization. This issue stems from the improper configuration of the default umask value for the init process, which is responsible for initializing and managing system services. The kernel's Korean installation program incorrectly sets the umask to 000, a value that grants full permissions to all users including read, write, and execute access. This misconfiguration directly impacts the security posture of the entire system by allowing any user to modify critical system files and directories that should remain protected from unauthorized access. The vulnerability creates a persistent security risk that can be exploited by both local and potentially remote attackers to gain elevated privileges and compromise system integrity.
The technical flaw manifests through the improper initialization of umask values during the boot process when the Korean installation program executes. Umask values control the default permissions for newly created files and directories by specifying which permission bits should be excluded from the default permissions. A umask of 000 means no permission bits are masked out, resulting in files being created with full permissions for all users. This configuration directly violates the principle of least privilege and allows attackers to modify system-critical files such as configuration files, binaries, and system libraries. The vulnerability is particularly dangerous because it affects the init process which is fundamental to system operation, meaning that any files created during system initialization or subsequent operations will inherit these insecure permissions. This flaw can be classified under CWE-276, which deals with improper file permissions, and represents a direct violation of proper system hardening practices.
The operational impact of this vulnerability extends far beyond simple permission issues and creates a comprehensive security compromise for systems running the affected kernel version. When files are created with world-writeable permissions, attackers can modify system binaries, configuration files, and service scripts to gain unauthorized access or execute malicious code. The vulnerability allows for privilege escalation attacks where local users can manipulate system files to achieve root access, and potentially enables remote exploitation if network services are running with elevated privileges. The security implications include unauthorized modification of system files, installation of backdoors, and the ability to corrupt system functionality. Additionally, this flaw can be leveraged in conjunction with other vulnerabilities to create more sophisticated attack vectors. The vulnerability's impact is amplified by the fact that it affects the core system initialization process, making it persistent across system reboots and difficult to detect through normal security monitoring procedures. This vulnerability aligns with ATT&CK technique T1068, which involves exploiting local system privileges to escalate access, and T1078, which covers legitimate credentials use for system access.
Mitigation strategies for this vulnerability require immediate system patching and configuration hardening measures. The most effective solution is to upgrade to a patched kernel version that properly configures the umask value for the init process, ensuring that default file permissions are set appropriately. System administrators should verify that umask values are correctly configured in all system initialization scripts and that the default umask is set to a secure value such as 022, which prevents world-writeable permissions for newly created files. Additional security measures include implementing proper file integrity monitoring to detect unauthorized changes to critical system files, conducting regular permission audits to identify files with inappropriate permissions, and ensuring that system services are running with minimal required privileges. Organizations should also implement proper access controls and monitoring for system initialization processes to prevent unauthorized modifications to critical system components. The vulnerability demonstrates the importance of secure default configurations and proper system hardening practices that align with security frameworks such as NIST SP 800-53 and ISO 27001 standards for system security management.