Trojan as Fake Google Chrome Extension

The story is simple: Google Chrome users receive an unsolicited e-mail which announces that a new extension of their favorite browser has been developed to facilitate their access to documents from e-mails.

Fig. 1 The spam message used to popularize the malicious link

An apparently unsuspicious link is provided, and the recipients are advised to follow it in order to download the new extension.  Once they click the link, they are redirected to a look-alike of the Google Chrome Extensions page, which, instead of the promised extension, provides them with a fake application that infects their systems with malware.

Although the sham application has the same description as that of an original Google Chrome Extension, the first sign the more inquisitive users will get about it not being what they were looking for should be the fact that instead of the expected “.crx” extension, it features a flamboyant “.exe” tail.

Fig. 2 The Trojan’s hideaway

Identified by BitDefender as Trojan.Agent.20577the application modifies the Windows HOSTS file in an attempt to block access to Google and Yahoo webpages. Every time users want to access them and write “google.[xxx]” or “[xx].search.yahoo.com” in the web browser, they will be redirected to another IP:  89.149.xxx.xxx . This allows the malware creators to intercept the victims’ calls to reach the respective sites. In this way, the credulous users will be redirected to the cybercriminals’ own malware-laden versions of those sites.

The malware description was made available courtesy of Daniel Chipiristeanu, BitDefender virus researcher