CVE-2009-2657 in nilfs
Summary
by MITRE
nilfs-utils before 2.0.14 installs multiple programs with unnecessary setuid privileges, which allows local users to execute arbitrary commands via the device string in a -c command line option to mkfs.nilfs2.
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Analysis
by VulDB Data Team • 11/20/2018
The vulnerability identified as CVE-2009-2657 affects the nilfs-utils package version 2.0.14 and earlier, presenting a critical security flaw in the handling of setuid permissions for multiple utility programs. This issue stems from the improper privilege management within the nilfs2 filesystem utilities, specifically concerning the mkfs.nilfs2 command that creates nilfs2 filesystems. The flaw allows local attackers to escalate their privileges and execute arbitrary code through a carefully crafted device string parameter passed via the -c command line option. The root cause lies in the insufficient validation of user-supplied input within the setuid context, creating an exploitation vector that bypasses normal security boundaries.
The technical implementation of this vulnerability involves the mkfs.nilfs2 utility running with elevated privileges due to its setuid bit being enabled for the root user. When a malicious user passes a specially crafted device string through the -c option, the utility fails to properly sanitize or validate the input before processing it. This allows for command injection attacks where arbitrary shell commands can be executed with root privileges. The vulnerability is classified under CWE-20, which describes improper input validation, and specifically relates to CWE-78, which addresses improper neutralization of special elements used in OS commands. The flaw represents a privilege escalation vulnerability that directly violates the principle of least privilege, as programs should only run with the minimum necessary permissions.
From an operational impact perspective, this vulnerability poses significant risks to systems utilizing nilfs2 filesystems, particularly those running older versions of the nilfs-utils package. Local attackers with basic user accounts can exploit this weakness to gain root access, potentially leading to complete system compromise. The attack vector is particularly concerning because it requires minimal prerequisites and can be executed through standard command-line interactions. The vulnerability affects systems where nilfs2 is the primary filesystem type, commonly found in embedded systems, storage appliances, and Linux distributions that support this specific filesystem implementation. The exploitation process is straightforward and does not require specialized tools beyond standard user-level access.
Mitigation strategies for CVE-2009-2657 involve immediate patching of the nilfs-utils package to version 2.0.14 or later, which addresses the improper privilege handling and input validation issues. System administrators should also implement privilege reduction measures by reviewing and removing unnecessary setuid permissions from filesystem utilities where possible. The recommended approach includes conducting thorough security audits of all setuid programs and ensuring proper input sanitization is implemented in all utilities that process user-supplied data. Additionally, organizations should implement monitoring solutions to detect unusual command execution patterns that might indicate exploitation attempts. This vulnerability aligns with ATT&CK technique T1068, which covers local privilege escalation through the exploitation of system vulnerabilities, and T1548.001, covering abuse of setuid and setgid binaries. The remediation process should include comprehensive system hardening measures to prevent similar issues in other utilities and maintain overall system security posture.