Cybersecurity research highlights risks of chaining low-level vulnerabilities

A recent application penetration test demonstrated how multiple lower-risk vulnerabilities can be chained together to create a serious exploit capable of capturing user credentials.

During the engagement, researchers identified a stored cross-site scripting (XSS) vulnerability within an application's login functionality. While the application attempted to sanitize input by removing certain HTML blocks and renaming event handlers, researchers successfully identified the “onanimationend” event handler through fuzzing. This allowed for script execution on the login page.

To facilitate the attack, researchers utilized an image upload feature. They discovered that while the application verified byte headers, it would rename .jpg files to .png without altering the underlying content. By using the XSS exploit to execute a JavaScript function, the team was able to fetch files from the server and execute content following the binary JPEG header, successfully bypassing security measures.