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message-postinator

A tool for testing the security of apps that leverage postMessage()

Try it now: postinator.jaytonbirch.com

Screenshot 2023-10-09 at 10 25 06 AM

What is this for?

The problem

A web client is vulnerable to poisonous messaging when it:

  • reflects user-defined iframes
  • listens for messages without source-checking

Check out the mdn docs regarding security concerns with postMessage()

Using message-postinator

Blaster Builder

message-postinator can be used to build webpages that post messages that you define to the frame's parent. You can then test web apps that reflect user-defined iframes by using the message blaster that you created.

Playground

You can test your Blasters in the playground