This extension passively detects potential denial of service attacks due to the size of an image being specified in request parameters.

When serving image assets, many web developers find it useful to have a feature that scales the image to a size specified in a URL parameter. Such functionality can not only be used for scaling images down but also making them huge, this leads to Denial of Service (DoS).

In active scanning mode the extension also detects ImageTragick (CVE-2016-3714) in an experimental manner based on timing.

Please refer to the blog post for more details.