Yahoo! Spread Bitcoin Mining Botnet Malware Via Ads


Bitcoin and other cryptocurrencies are pretty much headline news every day now, especially with the inflated values (Bitcoin over $1000 recently). We haven’t mentioned them for a long time though, back in 2012 we wrote about Hackers breaking into a Bitcoin Exchange Site called Bitcoinica.

There have been plenty of Bitcoin related hacks since then, mostly targeting exchanges, but there have been some other interesting developments like these so called bitnets, which are basically Bitcoin Mining malware botnets.

The most recent news is that Yahoo! recently served up some adverts which contained malware, the intent of the malware is to create a Bitcoin mining botnet.

Yahoo confirmed that for a four-day period in January, malware was served in ads on its homepage. Experts estimate that as many as two million European users could have been hit. Security firm Light Cyber said the malware was intended to create a huge network of Bitcoin mining machines.

“The malware writers put a lot of effort into making it as efficient as possible to utilise the computing power in the best way,” Light Cyber’s founder Giora Engel told the BBC.

Bitcoin mining malware is designed to steal computing power to make it easier for criminals to accumulate the virtual currency with little effort on their part.

“Generating bitcoins is basically guessing numbers,” said Amichai Shulman, chief technology office of security firm Imperva. “The first one to guess the right number gets 25 bitcoins and if you have a large volume of computers guessing in a co-ordinated way then you have a more efficient way of making money,” he added.

Other than a computer running slower, victims will be unaware that their machine is being used in what could become known as a “bitnet”. It is a variation on the traditional botnet, networks of malware-infected computers used to churn out spam or bombard websites with requests in order to knock them offline. Some experts estimate that such networks could be generating as much as $100,000 (£60,000) each day.

If the estimates are true, then whoever wrote this malware and managed to get it onto the Yahoo! frontpage could be minting money – $100,000 a day! That’s 3 million bucks a month, certainly no chump change.

I’d be interested to know more though, as CPU mining for Bitcoin is incredibly inefficient – so I wonder if this malware also harnesses GPU minining – which whilst can’t be compared to ASICS miners – still has a decent amount of grunt.


Yahoo acknowledged the attack in a statement earlier this week.

“From December 31 to January 3 on our European sites, we served some advertisements that did not meet our editorial guidelines – specifically, they spread malware,” the statement read.

It went on to say that users in America, Asia and Latin America weren’t affected but did not specify how many European users were victims. Fox IT, the Dutch cybersecurity firm which revealed the malware attack, estimates that there were around 27,000 infections every hour the malware was live on the site. Over the period of the attack that could mean as many as two million machines were infected. Such attacks may be hard to avoid, said Mr Shulman.

“For an ad platform it is virtually impossible to guarantee 100% malware free ads. There are many independent stakeholders involved in the process of web advertising, so from time to time any ad platform is bound to deliver malware.”

It’s a pretty scary thought that no ad platform can be malware free, but honestly I’ve never experienced Google Adsense serving any kind of malware – although when I’m browsing on mobile lately I’ve had a lot of sides trying to push random .apk files to me.

It seems to like it was only regional as well with European users being targeted (perhaps due to the advert geo-targeting) – but with up to 2 million people infected – that’s a fairly decent sized Bitcoin mining botnet.

Source: BBC News

Posted in: Cryptography, Malware, Web Hacking

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