Cybercrooks have put together a malicious version of popular FTP app FileZilla which works just like the real thing but surreptitiously passes login information to a hacker-controlled server.
The evil twin version has the same look and feel as the genuine programme and is clearly designed to mask its suspicious activities, such as phoning home with compromised data and changes system files.
The trojanised version of Filezilla is actually 6.8MB smaller than the genuine article even though it comes packed with two extra malicious DLL libraries that don't feature in the genuine code.
The fake version is designed not to install updates, a tactic that along with its stealth features adds up to a threat designed to avoid removal or detection on compromised systems for the maximum time possible.
A write up of the threat, complete with screenshots and code analysis, can be found in a blog post by freebie anti-virus software firm Avast.
"Beware of malformed FileZilla FTP client versions 3.7.3 and 3.5.3," Avast warns. "We have noticed an increased presence of these malware versions of famous open source FTP clients."
"The [bogus] installer is mostly hosted on hacked websites with fake content," it adds.
Compromised FTP logins can be used to plant malware on associated sites or steal data, among others things. The varmints behind the FileZilla attack and their ultimate purpose remains unclear at present. ®