CVE-2024-56433: shadow-utils
CVE-2024-56433 is a critical vulnerability affecting the shadow-utils package, specifically versions 4.4 through 4.17.0. This vulnerability arises from the default behavior of the 
/etc/subuid configuration, which assigns user IDs (UIDs) in the range of 100000 to 165535 for the first user account. This default setting can lead to conflicts with UIDs assigned to users on locally administered networks, potentially resulting in account takeovers.(Dec 26, 2024)Nature of the Vulnerability
The primary concern with CVE-2024-56433 is that it allows for unauthorized access to resources, particularly when leveraging tools like newuidmap. This tool can manipulate user namespaces, which are critical for managing user permissions in Linux environments. The vulnerability can be exploited in scenarios involving:- NFS Home Directories: Attackers could gain access to NFS (Network File System) home directories by exploiting UID conflicts.
- Remote Logins: If local network users have UIDs that overlap with those defined in
/etc/subuid, a malicious actor could hijack sessions or resources.
Technical Implications
The implications of this vulnerability are significant for system administrators and users alike:- Account Takeover Risks: If a malicious user can map their UID to a UID in the
/etc/subuidrange, they can gain unauthorized access to files and processes owned by legitimate users. - Resource Access Conflicts: The overlapping UIDs may lead to unintended access to shared resources, compromising data integrity and confidentiality.
Recommendations for Mitigation
To mitigate the risks associated with CVE-2024-56433, system administrators should consider the following actions:- Review UID Assignments: Ensure that UIDs assigned within local networks do not overlap with the ranges defined in
/etc/subuid. - Update Shadow-utils: Upgrade to versions beyond 4.17.0, where this behavior may have been addressed.
- Implement User Namespace Isolation: Use user namespaces judiciously to limit the impact of potential UID conflicts.
Conclusion
CVE-2024-56433 highlights a critical security issue within the shadow-utils package that could lead to serious vulnerabilities in multi-user environments, especially those utilizing NFS or similar resource-sharing mechanisms. By understanding the nature of this vulnerability and implementing recommended mitigations, organizations can better protect themselves against potential account takeovers and unauthorized access incidents.- https://nvd.nist.gov/