问题 A few months ago, a hidden iFrame started showing up on every page on every site on our dedicated server. When we took the sites down for maintenance with a 503, the iFrame was still there on the down for maintenance page. Eventually, the host blocked the source of the iFrame, but we never found the backdoor. The injected iFrame looked something like this, but wrapped in a style tag to obfuscate and with various URLs: iframe src="http://heusnsy.nl/32283947.html.. We moved our smaller sites to