COMMON WEAKNESS ENUMERATIONIncomplete

CWE-1385

Missing Origin Validation in WebSockets

The product uses a WebSocket, but it does not properly verify that the source of data or communication is valid.

Abstraction

Variant

Structure

Simple

Likelihood of Exploit

Medium

Understand the problem

What is the problem?

The product uses a WebSocket, but it does not properly verify that the source of data or communication is valid.

Extended description

WebSockets provide a bi-directional low latency communication (near real-time) between a client and a server. WebSockets are different than HTTP in that the connections are long-lived, as the channel will remain open until the client or the server is ready to send the message, whereas in HTTP, once the response occurs (which typically happens immediately), the transaction completes. A WebSocket can leverage the existing HTTP protocol over ports 80 and 443, but it is not limited to HTTP. WebSockets can make cross-origin requests that are not restricted by browser-based protection mechanisms such as the Same Origin Policy (SOP) or Cross-Origin Resource Sharing (CORS). Without explicit origin validation, this makes CSRF attacks more powerful.

Terminology

Alternate terms and usages

Cross-Site WebSocket hijacking (CSWSH)

this term is used for attacks that exploit this weakness

Root cause

How and when does the problem arise?

Lifecycle phase

Architecture and Design

Lifecycle phase

Implementation

Risk

What does successful exploitation lead to?

Varies by ContextGain Privileges or Assume IdentityBypass Protection MechanismRead Application DataModify Application DataDoS: Crash, Exit, or Restart

Affected security scopes: Confidentiality, Integrity, Availability, Non-Repudiation, Access Control

The consequences will vary depending on the nature of the functionality that is vulnerable to CSRF. An attacker could effectively perform any operations as the victim. If the victim is an administrator or privileged user, the consequences may include obtaining complete control over the web application - deleting or stealing data, uninstalling the product, or using it to launch other attacks against all of the product's users. Because the attacker has the identity of the victim, the scope of the CSRF is limited only by the victim's privileges.

Defence

How is it prevented and fixed?

Implementation

Implementation-phase defence

Detail
Enable CORS-like access restrictions by verifying the 'Origin' header during the WebSocket handshake.

Implementation

Implementation-phase defence

Detail
Use a randomized CSRF token to verify requests.

Implementation

Implementation-phase defence

Detail
Use TLS to securely communicate using 'wss' (WebSocket Secure) instead of 'ws'.

Architecture and Design · Implementation

Defence to apply across several lifecycle phases

Detail
Require user authentication prior to the WebSocket connection being established. For example, the WS library in Node has a 'verifyClient' function.

Implementation

Implementation-phase defence

Detail
Leverage rate limiting to prevent against DoS. Use of the leaky bucket algorithm can help with this.

Effectiveness: Defense in Depth

Implementation

Implementation-phase defence

Detail
Use a library that provides restriction of the payload size. For example, WS library for Node includes 'maxPayloadoption' that can be set.

Effectiveness: Defense in Depth

Implementation

Implementation-phase defence

Detail
Treat data/input as untrusted in both directions and apply the same data/input sanitization as XSS, SQLi, etc.