DOM XSS Exploit: Using postMessage and JSON.parse in iframe Attacks
1 min read
Summary
This write-up presents a lab example of a DOM-based Cross-Site Scripting (XSS) vulnerability employing web messages and JSON.parse.
The vulnerability occurs when an attacker sends a malicious message to a web page using the postMessage API, and the receiving page blindly parses the message with JSON.parse without validating the source or the content of the message.
The lab demonstrates how an attacker can send a specially crafted message from an iframe to the parent page, exploiting the lack of validation to execute arbitrary JavaScript code in the parent page, resulting in a DOM XSS scenario.
The write-up provides a detailed explanation of the vulnerability, the attack scenario, and how an attacker could exploit it, along with recommendations for mitigation.
It stresses the importance of validating the source and content of web messages to prevent such potential security vulnerabilities.