CVE-2006-0071 in Linux
Summary
by MITRE
The ebuild for pinentry before 0.7.2-r2 on Gentoo Linux sets setgid bits for pinentry programs, which allows local users to read or overwrite arbitrary files as gid 0.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 07/07/2021
The vulnerability described in CVE-2006-0071 represents a critical privilege escalation flaw within the pinentry package ecosystem on Gentoo Linux systems. This issue affects versions prior to 0.7.2-r2 and stems from improper permission handling during the package installation process. The pinentry programs are essential components used by gpg and other cryptographic tools to securely handle passphrase entry, making this vulnerability particularly dangerous as it directly impacts the security of cryptographic operations. The flaw manifests through the improper setting of setgid bits on the pinentry executables, creating a pathway for local attackers to exploit the system's privilege model.
The technical root cause of this vulnerability lies in the ebuild script's handling of file permissions during package installation. When the ebuild for pinentry versions before 0.7.2-r2 executes, it incorrectly configures the setgid bit on the pinentry programs, granting group id 0 permissions to these executables. This configuration allows local users to leverage the setgid functionality to perform operations that should normally be restricted to the root user or specific privileged groups. The vulnerability specifically enables attackers to read or overwrite arbitrary files with the privileges of group 0, which typically corresponds to the root group or a system administration group with elevated permissions. This misconfiguration creates a direct pathway for privilege escalation and arbitrary file manipulation.
The operational impact of this vulnerability extends beyond simple local privilege escalation, as it undermines the fundamental security assumptions of cryptographic tooling on affected systems. Attackers can exploit this flaw to read sensitive files that are normally protected by the system's permission model, potentially accessing cryptographic keys, configuration files, or other sensitive data. The vulnerability also enables attackers to overwrite arbitrary files, which could lead to system compromise through file corruption, privilege escalation, or even complete system takeover. Given that pinentry programs are integral to cryptographic operations, this vulnerability directly impacts the security of gpg-based encryption and authentication systems, potentially compromising the confidentiality and integrity of encrypted data and communications.
This vulnerability aligns with CWE-276, which addresses improper file permissions and inadequate access control mechanisms. The flaw demonstrates poor privilege management and improper permission assignment within the package management system, creating a security boundary violation that allows unauthorized access to system resources. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques, specifically leveraging setuid/setgid permissions to gain elevated privileges. The attack vector represents a local privilege escalation opportunity that could be exploited by any user with access to the affected system, making it particularly concerning for multi-user environments. Organizations should prioritize patching this vulnerability as it provides a straightforward path for attackers to escalate privileges and access sensitive system resources.
The mitigation strategy for this vulnerability requires immediate patching of the affected pinentry package to version 0.7.2-r2 or later, which properly handles setgid bits and file permissions. System administrators should also conduct thorough audits of setgid and setuid permissions on cryptographic tools and related executables to ensure no other similar vulnerabilities exist. Additionally, implementing proper package management practices and regular security assessments can help prevent similar issues from arising in the future. The vulnerability serves as a reminder of the importance of careful permission handling in security-critical software components and the necessity of regular security reviews of package installation processes.