Millions of mobile phones come pre-infected with malware, say researchers

The threat is coming from inside the supply chain

Black Hat Asia Miscreants have infected millions of Androids worldwide with malicious firmware before the devices even shipped from their factories, according to Trend Micro researchers at Black Hat Asia.

This hardware is mainly cheapo Android mobile devices, though smartwatches, TVs, and other things are caught up in it.

The gadgets have their manufacturing outsourced to an original equipment manufacturer (OEM). That outsourcing makes it possible for someone in the manufacturing pipeline – such as a firmware supplier – to infect products with malicious code as they ship out, the researchers said.

This has been going on for a while, we think; for example, we wrote about a similar headache in 2017. The Trend Micro folks characterized the threat today as "a growing problem for regular users and enterprises." So, consider this a reminder and a heads-up all in one.

“What is the easiest way to infect millions of devices?” posed senior Trend Micro researcher Fyodor Yarochkin, speaking alongside colleague Zhengyu Dong at the conference in Singapore.

Yarochkin compared infiltrating devices at such an early stage of their life cycle to a tree absorbing liquid: you put the infection at the root, and it gets distributed everywhere, out to every single limb and leaf.

This insertion of malware began as the price of mobile phone firmware dropped, we're told. Competition between firmware distributors became so furious that eventually the providers could not charge money for their product.

“But of course there’s no free stuff,” said Yarochkin, who explained that, as a result of this cut-throat situation, firmware started to come with an undesirable feature – silent plugins. The team analyzed dozens of firmware images looking for malicious software. They found over 80 different plugins, although many of those were not widely distributed.

The plugins that were the most impactful were those that had a business model built around them, were sold on the underground, and marketed in the open on places like Facebook, blogs, and YouTube.

The objective of the malware is to steal info or make money from information collected or delivered.

The malware turns the devices into proxies which are used to steal and sell SMS messages, take over social media and online messaging accounts, and used as monetization opportunities via adverts and click fraud.

One type of plugin, proxy plugins, allow the criminal to rent out devices for up to around five minutes at a time. For example, those renting the control of the device could acquire data on keystrokes, geographical location, IP address and more.

“The user of the proxy will be able to use someone else’s phone for a period of 1200 seconds as an exit node,” said Yarochkin. He also said the team found a Facebook cookie plugin that was used to harvest activity from the Facebook app.

Through telemetry data, the researchers estimated that at least millions of infected devices exist globally, but are centralized in Southeast Asia and Eastern Europe. A statistic self-reported by the criminals themselves, said the researchers, was around 8.9 million.

As for where the threats are coming from, the duo wouldn’t say specifically, although the word “China” showed up multiple times in the presentation, including in an origin story related to the development of the dodgy firmware. Yarochkin said the audience should consider where most of the world's OEMs are located and make their own deductions.

“Even though we possibly might know the people who build the infrastructure for this business, its difficult to pinpoint how exactly the this infection gets put into this mobile phone because we don’t know for sure at what moment it got into the supply chain,“ said Yarochkin.

The team confirmed the malware was found in the phones of at least 10 vendors, but that there was possibly around 40 more affected. For those seeking to avoid infected mobile phones, they could go some way of protecting themselves by going high end. That is to say, you'll find this sort of bad firmware in the cheaper end of the Android ecosystem, and sticking to bigger brands is a good idea though not necessarily a guarantee of safety.

“Big brands like Samsung, like Google took care of their supply chain security relatively well, but for threat actors, this is still a very lucrative market,” said Yarochkin. ®

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