Source: cve@mitre.org
TIOCCONS in SunOS 4.1.1 does not properly check the permissions of a user who tries to redirect console output and input, which could allow a local user to gain privileges.
CVE-1999-1197 exposes a critical vulnerability in SunOS 4.1.1, allowing local users to escalate privileges by manipulating console input/output redirection. This flaw stems from inadequate permission checks within the TIOCCONS system call, potentially granting unauthorized access to sensitive system resources and data, leading to complete system compromise.
Step 1: Identify Target Process: The attacker identifies a privileged process that interacts with the console, such as init or login.
Step 2: Craft Malicious Input: The attacker crafts a malicious input string designed to execute a privileged command (e.g., adding a user to the root group, modifying system files).
Step 3: Redirect Console I/O: The attacker uses the TIOCCONS ioctl call to redirect the console input of the targeted privileged process to the crafted malicious input.
Step 4: Trigger Execution: The attacker triggers the execution of the privileged process, causing it to read the malicious input from the redirected console.
Step 5: Privilege Escalation: The privileged process executes the malicious command, granting the attacker elevated privileges (e.g., root access).
The vulnerability lies within the TIOCCONS ioctl call in SunOS 4.1.1. Specifically, the system fails to properly validate the permissions of a user attempting to redirect console input and output. When a user attempts to redirect console I/O, the system does not adequately verify if the user has the necessary privileges to perform this action. This lack of proper authorization check allows a local user to potentially redirect console input to a privileged process, such as init or login, and inject malicious commands. This can lead to arbitrary code execution with elevated privileges, effectively granting the attacker root access. The root cause is a privilege escalation vulnerability due to a missing or insufficient permission check within the TIOCCONS ioctl handler. The flaw allows a low-privileged user to manipulate the console, bypassing the intended security controls.
Due to the age of the vulnerability, it's unlikely to be directly targeted by modern APTs. However, it could be leveraged in targeted attacks against legacy systems or as part of a broader attack chain. The vulnerability is not listed on the CISA KEV catalog.
Monitor system logs for suspicious ioctl calls, specifically those related to TIOCCONS and console redirection.
Analyze process execution logs for unexpected behavior from privileged processes, such as init or login.
Inspect system files for unauthorized modifications, especially those related to user accounts or system configuration.
Network traffic analysis for unusual console activity or command injection attempts.
Monitor for the creation of new user accounts or the modification of existing user privileges.
Upgrade to a patched version of SunOS or a supported operating system. This is the most effective remediation.
If upgrading is not possible, apply any available security patches for SunOS 4.1.1. (Unlikely to exist).
Implement strict access controls and least privilege principles to limit the impact of a successful exploit.
Regularly audit system logs for suspicious activity.
Use intrusion detection and prevention systems (IDS/IPS) to monitor for and block malicious activity.
Consider isolating vulnerable systems in a separate network segment to limit their exposure.