CVE-2004-2768 in dpkg
Summary
by MITRE
dpkg 1.9.21 does not properly reset the metadata of a file during replacement of the file in a package upgrade, which might allow local users to gain privileges by creating a hard link to a vulnerable (1) setuid file, (2) setgid file, or (3) device, a related issue to CVE-2010-2059.
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Analysis
by VulDB Data Team • 02/06/2019
The vulnerability identified as CVE-2004-2768 represents a critical flaw in the dpkg package management system version 1.9.21 that affects Unix-like operating systems. This issue stems from improper metadata handling during package upgrade operations, specifically when replacing existing files. The flaw occurs because dpkg fails to correctly reset file attributes and permissions when upgrading packages that contain setuid, setgid, or device files. This failure creates a persistent security risk that can be exploited by local attackers to escalate privileges.
The technical implementation of this vulnerability involves the dpkg package manager's handling of file replacement during upgrade operations. When a package is upgraded, dpkg should ensure that all metadata associated with replacement files is properly reset to match the new package's intended configuration. However, in version 1.9.21, the system does not adequately reset file permissions, ownership, or other critical metadata attributes. This oversight allows attackers to manipulate file properties through hard link creation, exploiting the fact that the upgrade process leaves behind old metadata that persists in the filesystem.
The operational impact of this vulnerability is significant for system security and integrity. Local users who can create hard links to vulnerable files can potentially manipulate the permissions and ownership of setuid and setgid binaries, thereby gaining elevated privileges on the system. This vulnerability directly relates to the broader category of privilege escalation attacks and specifically aligns with attack patterns described in the ATT&CK framework under privilege escalation techniques. The flaw affects any system running dpkg version 1.9.21 where package upgrades occur, making it particularly dangerous in environments where regular package maintenance is performed.
From a compliance and security standards perspective, this vulnerability maps directly to CWE-276, which describes improper file permissions and access control issues. The flaw also connects to CWE-732, which deals with incorrect permissions for critical resources, and CWE-362, which addresses concurrent execution with improper access control. The security implications extend beyond simple privilege escalation to encompass potential system compromise through manipulation of critical system files. Organizations using affected versions of dpkg should immediately implement mitigation strategies including upgrading to patched versions, implementing proper file permission monitoring, and conducting thorough security audits of setuid/setgid binaries on affected systems.
The remediation approach requires immediate deployment of updated dpkg versions that properly address the metadata reset functionality during package upgrades. System administrators should also implement additional controls such as file integrity monitoring, regular permission audits, and restriction of package upgrade operations to privileged users only. The vulnerability highlights the critical importance of proper file attribute handling in package management systems and demonstrates how seemingly minor implementation flaws can lead to substantial security risks. Organizations must ensure that their package management processes maintain strict integrity controls to prevent similar issues from occurring in other software components that handle file replacement operations.