Source: cve@mitre.org
Vulnerability in restore in SunOS 4.0.3 and earlier allows local users to gain privileges.
SunOS 4.0.3 and earlier systems are vulnerable to a local privilege escalation via a flaw in the restore utility. This vulnerability allows attackers to gain root access, potentially leading to complete system compromise and data exfiltration. The age of the affected systems makes them a prime target for attackers seeking to exploit legacy infrastructure.
Step 1: Preparation: The attacker creates a malicious backup archive. This archive contains files designed to overwrite critical system files or modify their permissions.
Step 2: Exploitation: The attacker executes the restore utility, typically with specific command-line arguments (e.g., -x to extract files, -f to specify the backup archive) and the malicious archive as input.
Step 3: Privilege Escalation: The restore utility, due to the vulnerability, fails to properly validate the attacker's permissions before restoring files. The attacker's crafted archive overwrites critical system files (e.g., /etc/passwd) or changes their ownership to the attacker's user ID.
Step 4: Root Access: By controlling the contents or permissions of critical system files, the attacker can then gain root access, for example, by adding a new user with root privileges or modifying the password hash of an existing user.
The vulnerability lies within the restore utility's handling of file metadata and permissions during the restoration process. Specifically, the flaw stems from insufficient input validation and improper handling of file ownership and permissions when restoring files from a backup. The restore utility, when executed with certain options or crafted input, fails to correctly verify the user's privileges before setting file ownership or modifying file attributes. This allows a local user to manipulate the restoration process to gain ownership of critical system files, such as /etc/passwd or /etc/shadow, and subsequently elevate their privileges to root.
This vulnerability is highly relevant to threat actors targeting legacy systems. While no specific APT groups are directly linked to this specific CVE, any actor targeting legacy infrastructure would likely be aware of and potentially exploit this vulnerability. CISA KEV status: Not Listed due to the age and limited modern relevance.
Monitor system logs for unusual restore command executions, especially those with suspicious arguments (e.g., -x, -f, and potentially -i).
Analyze file system changes, particularly modifications to /etc/passwd, /etc/shadow, and other critical system files.
Implement file integrity monitoring (FIM) to detect unauthorized changes to critical system files.
Network traffic analysis may reveal unusual activity if the attacker attempts to establish a remote connection after gaining root access.
Upgrade to a supported version of SunOS that addresses this vulnerability (e.g., SunOS 4.1 or later).
If upgrading is not possible, apply the latest security patches available for the affected SunOS version.
Restrict access to the restore utility. Only authorized users should be able to execute it.
Implement strong access controls and least privilege principles to limit the impact of a successful exploit.
Regularly audit system logs and file integrity to detect and respond to suspicious activity.