Source: cve@mitre.org
fte-console in the fte package before 0.46b-4.1 does not drop root privileges, which allows local users to gain root access via the virtual console device.
Local privilege escalation is possible due to a flaw in the fte-console package, allowing unprivileged users to gain root access. This vulnerability stems from the failure of the application to properly relinquish elevated privileges after initialization, making the system susceptible to unauthorized access and control.
Step 1: User Interaction: A local, unprivileged user logs into the system or gains access to a shell.
Step 2: Vulnerability Trigger: The user interacts with the fte-console application, likely through the virtual console device. This could involve sending specific commands or data.
Step 3: Privilege Escalation: Because fte-console did not drop root privileges, the user's actions are executed with root privileges.
Step 4: Arbitrary Code Execution: The user leverages the root privileges to execute arbitrary code, potentially by writing to a privileged file or executing a privileged command. This could involve modifying system files, installing backdoors, or gaining full control of the system.
Step 5: System Compromise: The attacker now has root access and can perform any action on the system, leading to complete system compromise.
The vulnerability lies in the fte-console application's failure to drop root privileges after it has completed its initialization tasks. Specifically, the program, when started, likely runs with root privileges to perform certain operations related to the virtual console device. However, it does not subsequently relinquish these privileges, leaving the process running with elevated permissions. This means that any subsequent actions performed by the process, or any code that can be injected into the process, will also execute with root privileges. The root cause is a missing or improperly implemented setuid() or setgid() call after the initial privileged operations are complete. This allows a local user to interact with the virtual console device in a way that can lead to arbitrary code execution with root privileges, such as writing to a privileged file or executing a privileged command.
Due to the age of the vulnerability, it's unlikely to be directly associated with specific modern APT groups. However, any attacker with local access could leverage this vulnerability. The ease of exploitation makes it attractive for opportunistic attacks. This vulnerability is not listed in the CISA KEV catalog, but it's important to note that the absence of a listing does not equate to the absence of risk.
Monitor system logs for unexpected activity related to the fte-console process, especially commands executed with root privileges.
Analyze process execution history for fte-console and look for any unusual interactions with the virtual console device.
Check for modifications to system files or the installation of unexpected software that could indicate a compromise.
Use file integrity monitoring tools to detect unauthorized changes to critical system files.
Network traffic analysis may reveal unusual connections originating from the compromised system after exploitation.
Upgrade the fte package to version 0.46b-4.1 or later.
Implement least privilege principles, ensuring that applications run with the minimum necessary privileges.
Regularly audit system configurations and user accounts to identify and address potential vulnerabilities.
Employ a host-based intrusion detection system (HIDS) to monitor for suspicious activity.
Implement strong access controls to limit user access to sensitive system resources.
Consider using a security scanner to identify and patch vulnerabilities in all installed packages.