FTP virus spreading in new ways
An earlier blog post described how several of our customers got their personal computers infected by a new virus that has been spreading across the Internet. Initial versions of the virus spread themselves by reading a Web site’s FTP username and password stored on the PC, then downloading Web pages, inserting an “iframe” tag, and re-uploading the Web pages back to the server. As a proactive measure, we started scanning all uploaded files and stripping out any malicious “iframe” tags.
We are now seeing newer versions (commonly called “Gumblar”) which spread by inserting “script” tags with encoded JavaScript code. Because there are several variations of this approach, and because some legitimate commercial scripts use the same technique to hide their source code, we cannot perfectly identify and strip out these infections. Therefore, we will not automatically strip out the “script” tags from any upload file that looks suspicious.
