Google Chrome users are being targeted these days by a wave of attacks that uses malicious extensions hosted in the official Chrome Web Store. The attack appears to be of Turkish origin and is using Facebook to spread. We saw users of different nationalities infected with the malicious extensions, which the cybercriminals are sending to the official store regularly, in a cat-and-mouse game.

As we already reported in March 2012, Brazilian cybercriminals were able at that time to host a malicious extension in the Chrome Web Store. Since then in June 2012 Google has changed the way users can add third party browser extensions i.e. not allowing the installation that are not hosted on the official Web Store. More recently Google removed the possibility of silent installations, which has been widely abused by third parties.

Maybe for these reasons bad guys started to concentrate their efforts to upload bad extensions to the official store. Now it’s the turn of Turkish cybercriminals; they were able to host several extensions there in the last few days.

Brazilian cybercrime is based primarily on the spread of Trojan bankers. For some time now the country’s bad guys have been investing their efforts in new monetization schemes, the latest includes the use of adware. And the perfect place for distributing this sort of malware? Yes, that’s right – social networks. This is how "PimpMyWindow", an adware and click-fraud scheme that has infected several Brazilian Facebook users in recent days, works.

To spread quickly among innocent users the adware uses a "change the color of your profile" option that recently surfaced. The infected profiles are used to spread automatic messages to your Facebook contacts:

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. In this post, we will look into a Facebook worm that was written using the Crossrider system – a system still in beta testing.

Image source: http://crossrider.com

Since November 2011, according to recent statistics, Google Chrome has become the most popular browser in Brazil (more than 45% of the market share).

The same has is true for Facebook, which now is the most popular social network in Brazil, with a total of 42 million users, displacing Orkut.

These two facts are enough to motivate Brazil’s bad guys to turn their attentions to both platforms. This month we saw a huge wave of attacks targeting Brazilian users of Facebook, based on the distribution of malicious extensions. There are several themes used in these attacks, including “Change the color of your profile” and “Discover who visited your profile” and some bordering on social engineering such as “Learn how to remove the virus from your Facebook profile”:

1) Click on Install app, 2) Click on Allow or Continue, 3) Click on Install now, After doing these steps, close the browser and open again

This last one caught our attention not because it asks the user to install a malicious extension, but because the malicious extension it’s hosted at the official Google's Chrome Web Store. If the user clicks on “Install aplicativo” he will be redirected to the official store. The malicious extension presents itself as “Adobe Flash Player”:

At Virus Bulletin 2011, we presented on the exploding level of delivered Java exploits this year with "Firing the roast - Java is heating up again". We examined CVE-2010-0840 exploitation in detail, along with variants of its most common implementation on the web and some tools and tips for analysis. Microsoft’s security team presented findings for 2011 that mirrored ours in relation to Java exploit prevalence on the web – it is #1! At the same time, aside from the recent, well-known BEAST Java implementation, it is striking that it has been very uncommon to see Java backdoors, Trojans and spyware. But that lack of Java malware variety is beginning to change. My colleague, malware analyst Roman Unucheck, identified a new Java bot with some interesting characteristics that we named "Backdoor.Java.Racac".

These days, invites to the new social network created by Google are a popular subject among users that want to try it.

If a subject is popular it also can be used by cybercriminals as a trick to infect curious users – and Brazilian cybercriminals have already started sending fake invites with malicious links pointing to malware, specifically Trojan bankers.

Today we found one of them targeting Portuguese speakers:

There’s nothing new in Brazilian cybercriminals exploiting social networks to distribute their malicious code. Orkut was first, followed by Twitter, and now it’s Facebook’s turn.

Facebook is becoming increasingly popular in Brazil and we are witnessing more and more Brazilian bad guys switching their focus to it. We received some proof this weekend: a Brazilian instant message (IM) worm created to steal Facebook passwords and login, and use the infected profile to spread malicious links among Portuguese speakers.

The worm (md5 d8dd66f2ec659687c56feb31ae1ac692) is distributed in a drive-by-download attack. After infecting the user’s machine a malicious applet downloads lots of different files, including the IM worm responsible for stealing users’ Facebook passwords. The worm is designed to connect to the victim profile via the web service Ebuddy.com or via the mobile version of Facebook, and capable of posting the content of the file fb.txt:

It seems I’m not doing anything other than write about malware on Facebook, but here goes again. As you have probably read or seen yourself on Facebook, there are quite a few applications pretending to show you a list of people who have viewed your profile. I think the most common one is the “Stalker Application”.

Today I saw something that I haven’t seen before – the applications have changed tactics and have now been localized, meaning the page and message which is distributed is in different languages. In my case the language is Swedish, since I’m from Sweden, and I presume that the worms are also localized in other languages.

As with the other cases we have seen, the user is tricked into executing a JavaScript in their browser; that script then loads another script from another domain. The bad guys use this setup to make it harder for antivirus companies to block these domains. This particular case is pretty funny – because of a poorly configured web server we managed to get a complete list of all the domains used in this scam, and they have now been sent to our analysts so they can be blacklisted.

Continuing our investigation on the Osama's death campaign, we were especially concerned about the potential distribution of malware on social networks, because of their speed of propagation. So we have been monitoring Twitter, getting some million tweets and a huge number of URLs too. No surprise here as during the last 24 hours the average was 4.000 tweets per second related to this topic. Here you can see how even Internet traffic was affected.

Analyzing these URLs, we found some interesting stuff.

The first one is a Facebook scam campaign posing as Osama's death video:

Over the weekend, a lot of Facebook users started receiving malicious chat messages from their friends that looked like this:

“Father crashes and dies because of THIS message posted on his daughters profile wall!” - followed by a shortened URL (using the bit.ly URL shortening services). The missing apostrophe in the word "daughter's" - i.e. "daughter's profile wall" – could be a clue that the message is not genuine, or at least that the author is not a native English speaker, but let’s take a look at what would happen to a user who falls for this social engineering trick.