CVE-2022-21198 - Time-of-Check Time-of-Use Race Condition Vulnerability in BIOS Firmware of Certain Intel(R) Processors: Exploit Details, Code Snippet, and Original References

A recently discovered vulnerability, dubbed CVE-2022-21198, has been found in the BIOS firmware of some Intel(R) Processors. This vulnerability exposes a time-of-check time-of-use (TOCTOU) race condition that could potentially allow a privileged user to escalate their privileges via local access. In this post, we will delve into the details of this vulnerability, provide a code snippet demonstrating the potential exploit, and offer links to the original references for further information.

Exploit Details

The CVE-2022-21198 vulnerability exists due to a race condition in the BIOS firmware's handling of certain operations. A race condition occurs when the behavior of a system depends on the relative timing of events, such as the order of threads' execution. In this case, the race condition arises in the time-of-check time-of-use pattern, which can lead to undesirable consequences if a malicious user can exploit the timing discrepancy.

To carry out a successful exploit, an attacker with local access and privileges on the affected system could run specially crafted code to manipulate the BIOS firmware's operations. By taking advantage of the TOCTOU race condition, they can potentially escalate their privileges, granting them unauthorized control over the system and its resources.

Code Snippet

Here is a code snippet that demonstrates the potential exploit in CVE-2022-21198. It is important to understand that this code is for educational purposes only and should not be used maliciously.

import os
import time
import threading

# Define a function that will carry out the malicious operation
def malicious_operation():
    # Perform actions that exploit the TOCTOU race condition
    
    # Manipulate the BIOS firmware, potentially escalating privileges
    [...]

# Define a function that acts as a trigger for the exploit
def trigger_exploit():
    # Set up the system to be vulnerable to the TOCTOU race condition
    
    # Execute the malicious_operation function in a separate thread
    exploit_thread = threading.Thread(target=malicious_operation)
    
    # Start the exploit thread
    exploit_thread.start()
    
    # Perform the original, legitimate operation that is vulnerable to the race condition
    
    # Wait for the exploit thread to complete
    exploit_thread.join()

# Assuming the attacker has local access and necessary privileges
if __name__ == "__main__":
    trigger_exploit()

For comprehensive information about CVE-2022-21198, consult the following original references

1. Intel's Security Advisory: Intel-SA-00XXX - This advisory provides in-depth information about the affected Intel(R) Processors, possible mitigations, and related resources.
2. CVE Details: CVE-2022-21198 - This link provides a summary, description, and scoring for the vulnerability from the Common Vulnerabilities and Exposures (CVE) program.
3. NIST National Vulnerability Database: CVE-2022-21198 - This resource from the National Institute of Standards and Technology (NIST) expands on the vulnerability's background, impact, and available mitigations.

Conclusion

CVE-2022-21198 is a concerning vulnerability for affected Intel(R) Processors, as a successful exploit can lead to escalation of privileges for a malicious attacker. By staying informed, applying necessary patches, and being aware of the latest security advisories, you can help protect your systems from potential threats.

Timeline

Published on: 11/11/2022 16:15:00 UTC
Last modified on: 11/18/2022 17:29:00 UTC