A cross-browser extension development framework called Crossrider fell victim to malware writers in an effort to build a click-fraud worm that spreads on Facebook.
The API allows developers to write code that will run inside different browsers and, by extension, on different OSes. The framework is still in beta testing and its creators plan on adding support for Safari soon.
“It is quite rare to analyze a malicious file written in the form of a cross-platform browser plugin. It is, however, even rarer to come across plugins created using cross-browser engines,” said Kaspersky Lab malware expert Sergey Golovanov.
The new piece of malware is “LilyJade” and is for sale on underground forums for $1,000. Its creator said it can infect browsers running on Linux or Mac systems and that since it doesn’t have any executable files, no antivirus program will look for it.
The malware’s purpose appears to be click fraud. It is capable of spoofing rogue advertisement modules on Yahoo, YouTube, Bing/MSN, AOL, Google and Facebook, Golovanov said. When users view or click on these ads, the malware’s creators earn money through affiliate programs.
In order to spread, the malware leverages its control over infected browsers to piggyback on active Facebook sessions and send spam messages on behalf of authenticated Facebook users.
The links included in LilyJade’s Facebook spam messages direct users to compromised websites that load the Nuclear Pack exploit kit into a hidden iframe, Golovanov said.
Exploit kits like Nuclear Pack attempt to exploit vulnerabilities in outdated software — usually browser plug-ins like Java, Flash Player or Adobe Reader — in order to infect computers with malware.
The concept of malware running inside the browser as an extension is not new, but it seems to be more popular with malware writers.
Social networking worms also appear to be making a comeback. Symantec reported about a new variant of a worm called W32.Wergimog, which spreads by sending spam messages on Facebook, Hi5, Hyves, Linkedin, MySpace, Omegle and Twitter.
In addition, researchers from Trend Micro reported a different worm that spreads through several social networks and instant messaging applications.