CVE-2018-17153

What is this vulnerability?

CVE-2018-17153 is categorized as a critical Improper Authentication flaw with a CVSS base score of 9.8. Based on our vulnerability intelligence, this issue occurs when the application fails to securely handle untrusted data boundaries.

It was discovered that the Western Digital My Cloud device before 2.30.196 is affected by an authentication bypass vulnerability. An unauthenticated attacker can exploit this vulnerability to authenticate as an admin user without needing to provide a password, thereby gaining full control of the device. (Whenever an admin logs into My Cloud, a server-side session is created that is bound to the user's IP address. After the session is created, it is possible to call authenticated CGI modules by sending the cookie username=admin in the HTTP request. The invoked CGI will check if a valid session is present and bound to the user's IP address.) It was found that it is possible for an unauthenticated attacker to create a valid session without a login. The network_mgr.cgi CGI module contains a command called "cgi_get_ipv6" that starts an admin session -- tied to the IP address of the user making the request -- if the additional parameter "flag" with the value "1" is provided. Subsequent invocation of commands that would normally require admin privileges now succeed if an attacker sets the username=admin cookie.

This architectural defect enables adversaries to bypass intended security controls, directly manipulating the application's execution state or data layer. Immediate strategic intervention is required.

Risk Assessment

Impact on Systems

✅ Unauthorized Data Access: Attackers can bypass authorization controls to access other users' data or administrative endpoints.

✅ Account Takeover: Broken authentication or authorization may enable full account compromise without valid credentials.

✅ API Abuse: Exploiting this vulnerability enables mass data harvesting or destructive operations through unprotected API endpoints.

How to Fix and Mitigate CVE-2018-17153

1. Apply Vendor Patches: Upgrade affected components to their latest, non-vulnerable versions immediately.
2. Implement Input Validation: Ensure all user-supplied data is validated, sanitized, and type-checked before processing.
3. Deploy Runtime Protection: Use Precogs continuous monitoring to detect exploitation attempts in real time.
4. Audit Dependencies: Review and update all third-party libraries and transitive dependencies.

Defending with Precogs AI

Western Digital My Cloud devices contain an authentication bypass vulnerability. Unauthenticated attackers manipulate the cookie parameter to spoof an admin session, gaining full control over the NAS device. Precogs API Security Engine comprehensively audits session boundaries and authorization logic.

Use Precogs to continuously scan your codebase, binaries, APIs, and infrastructure for this vulnerability class and related attack patterns. Our AI-powered detection engine combines static analysis with threat intelligence to identify exploitable weaknesses before attackers do.

Start scanning with Precogs →

Vulnerability Code Signature

Attack Data Flow

Vulnerable Code Pattern

// ❌ VULNERABLE: Improper Authentication
app.post('/login', (req, res) => {
  const { username, password } = req.body;
  // Taint sink: weak or bypassable validation
  if (username === 'admin' || password === 'secret') {
    req.session.authenticated = true;
    res.send('Logged in');
  }
});

Secure Code Pattern

// ✅ SECURE: Robust Authentication
const bcrypt = require('bcrypt');
app.post('/login', async (req, res) => {
  const { username, password } = req.body;
  const user = await db.getUser(username);
  // Sanitized validation: secure password comparison
  if (user && await bcrypt.compare(password, user.passwordHash)) {
    req.session.authenticated = true;
    res.send('Logged in');
  } else {
    res.status(401).send('Invalid credentials');
  }
});

How Precogs Detects This

Precogs API Security Engine comprehensively audits endpoints to ensure strict authentication boundaries and secure logic.\n