Michał Bentkowski, Chief Security Researcher from security
The flaw, described by Google IT staff as an awesome XSS issue, resides in the AMP4Email feature rolled out in July. Bentkowski reported the vulnerability via the Google Vulnerability Reward Program in August 2019.
AMP4Email makes it easier the management of dynamic content
Even if AMP4Email implements a strong
“DOM Clobbering is a legacy feature of web browsers that just keeps causing trouble in many applications. Basically, when you create an element in HTML (for instance
The expert verified that the AMP4Email employs some protection against DOM Clobbering by forbidding certain values for the id attribute (i.e. AMP). However, the restriction
“AMP tries to get a property of AMP_MODE to put it in the URL,”
The researchers discovered that the code creates a new ‘script’ element, then it checks whether AMP_MODE.test and window.testLocation are both truthy.
Anyway, the code didn’t execute in the real-world case because of Content-Security-Policy deployed in AMP.
“I didn’t find a way to bypass the CSP, but when trying to do so, I found an interesting way of bypassing
Below the Gmail XSS vulnerability timeline:
(SecurityAffairs – Google Gmail, XSS)