posta: tool for researching Cross-document Messaging communication
Posta
Posta is a tool for researching Cross-document Messaging communication. It allows you to track, explore and exploit postMessage vulnerabilities and includes features such as replaying messages sent between windows within any attached browser.
Tabs
In the Tabs section, we can find our main Origin, with the iframes it hosts and communicates with through the session. We can choose the specific frame by clicking on it, and observe the postMessages related to that frame only.
Messages
In the Messages section, we can inspect all postMessage traffic being sent from the origin to its iframes, and vice versa. We can select specific communication for further examination by clicking on it. The Listeners area presents the code which is in charge of handling the communication, we can click and copy its contents for JS code observation.
Console
In the console section, we can modify the original postMessage traffic, and replay the messages with the tampered values which will be sent from the Origin to its iframe.
We should make tests and see if we can affect the behavior of the website by changing the postMessage content. If we manage to do so, it’s time to try and exploit it from a different Origin, by clicking “Simulate exploit”.
Exploit
Click on the “host” button in order to navigate to the exploitation window.
In the Exploit section, Posta will try and host the specified origin as an iframe in order to initiate postMessage communication. Most of the time we won’t be able to do so, due to X-Frame-Options being enabled on the origin website.
Therefore, in order to continue with our exploitation, we’ll need to gain communication reference with our Origin by initiating the window.open method, which can be achieved by clicking on “Open as tab”.
We have the console to our right which will help us modify and craft our specified payloads and test them in Cross-Origin Communication, initiated by clicking on the Exploit button.
Installation
Authors
- Chen Gour Arie
- Barak Tawily
- Gal Nagli
- Omer Yaron
