I have never experienced a malware until now, my hosting provider noticed me an issue and ToS violation, so they were about to suspend my account, it wasn't though one to clear by simply deleting the whole website :anyway: anyway, it wasn't an important website anyway so... but then I have...
Dear Friends, I Found this website to check whether your theme file is safe or not. You May or may not Know this website. So you can check the file before upload or install it.
website - http://themecheck.org