Source: cve@mitre.org
aspppd on Solaris 2.5 x86 allows local users to modify arbitrary files and gain root privileges via a symlink attack on the /tmp/.asppp.fifo file.
Solaris 2.5 x86 systems are vulnerable to a critical local privilege escalation via a symlink attack against the aspppd daemon. This vulnerability allows attackers to overwrite arbitrary files, potentially leading to root access and complete system compromise. The age of the vulnerability and the potential for legacy systems to be exposed makes this a significant risk if unpatched.
Step 1: Target Identification: Identify a Solaris 2.5 x86 system running aspppd.
Step 2: Symlink Creation: Create a symbolic link from /tmp/.asppp.fifo to a target file, such as /etc/shadow or a file containing a root user's SSH key.
Step 3: Triggering aspppd: Trigger the aspppd daemon to write to the FIFO file. This can be achieved by initiating a PPP connection or by other means that cause the daemon to attempt to write to the FIFO.
Step 4: File Overwrite: The aspppd daemon, unaware of the symlink, attempts to write data to /tmp/.asppp.fifo. Because of the symlink, this data is written to the target file (e.g., /etc/shadow).
Step 5: Privilege Escalation: The attacker crafts the data written to the target file to achieve their goal, such as adding a new user with root privileges or modifying an existing root user's password.
The vulnerability stems from a race condition within the aspppd daemon on Solaris 2.5 x86. The daemon creates a FIFO file (/tmp/.asppp.fifo) without proper security checks. An attacker can exploit this by creating a symbolic link to a critical system file (e.g., /etc/shadow) before aspppd attempts to write to the FIFO. This allows the attacker to overwrite the target file with attacker-controlled data, effectively gaining control of user credentials or other sensitive system configurations. The lack of input validation and secure file creation practices within the daemon allows for this arbitrary file overwrite.
While no specific APTs are directly linked to this CVE, the nature of the vulnerability (local privilege escalation) makes it attractive for any attacker seeking to gain root access. This vulnerability could be used as part of a broader attack chain. CISA KEV: Not Listed
Monitor file system activity for unexpected symlink creations in the /tmp directory, especially those pointing to sensitive system files like /etc/shadow, /etc/passwd, or SSH key files.
Analyze system logs for suspicious activity related to aspppd, including error messages or unexpected file access attempts.
Implement file integrity monitoring tools to detect changes to critical system files.
Network monitoring for PPP connection attempts, especially from internal hosts, that could be a trigger for the exploit.
Upgrade to a supported version of Solaris that addresses this vulnerability. This is the primary and most effective remediation.
If upgrading is not possible, apply any available patches or security updates for Solaris 2.5 x86.
Restrict access to the /tmp directory. Consider mounting /tmp with the nosuid and noexec options (though this may break some legitimate applications).
Regularly audit system configurations and file permissions to identify and address any potential security weaknesses.
Implement a host-based intrusion detection system (HIDS) to monitor for malicious activity.
Consider using a file integrity monitoring (FIM) tool to detect unauthorized changes to critical system files.