Check Point Researchers recently discovered a new variant of mobile malware that has quietly infected around 25 million Android devices, while the user remains completely unaware.
The apps, most of them games, were distributed through third-party app stores by a Chinese group with a legitimate business helping Chinese developers promote their apps on outside platforms.
Check Point is not identifying the company, because it is working with local law enforcement. About 300,000 devices were infected in the U.S.
The malware was able to copy popular apps on the phone, including WhatsApp and the web browser Opera, inject its own malicious code and replace the original app with the weaponised version, using a vulnerability in the way Google apps are updated. The hijacked apps would still work just fine, which hid the malware from users.
Armed with all the permissions users had granted to the real apps, “Agent Smith” was able to hijack other apps on the phone to display unwanted ads to users. That might not seem like a significant problem, but the same security flaws could be used to hijack banking, shopping and other sensitive apps, according to Aviran Hazum, head of Check Point’s analysis and response team for mobile devices.
“Hypothetically, nothing is stopping them from targeting bank apps, changing the functionality to send your bank credentials” to a third party, Hazum said.
“The user wouldn’t be able to see any difference, but the attacker could connect to your bank account remotely.”
The group also had 11 apps in the official Google Play store with a ‘dormant’ version of “Agent Smith,” which could have been triggered into action by a banner ad containing the keyword “infect.” The apps, which have been removed from the Google Play store, had been downloaded over 10 million times.
“The app developer can do nothing to prevent this,” said Hazum. “The fix has to come from the operating system.”
Google already fixed at least one of the Android exploits used by ‘Agent Smith,’ nicknamed Janus, in 2017 – but the fix hasn’t made its way onto every Android phone. It’s a potent reminder that millions of phones around the world are being used without the latest security measures.
“The sheer numbers infected by this campaign shows how many devices are not updated,” Hazum said. “It takes quite a lot of time for an update to reach every phone.”
A big part of the problem is how fragmented the Android ecosystem is, especially compared to the iPhone ecosystem.
Google is very good about releasing fixes for the vulnerabilities they know about, but getting it to all the devices is a very difficult problem.
Whenever Google issues a new security fix, or “patch,” every device maker — such as Samsung or LG — has to make sure all their own apps still work with the new system, which can take time.
Manufacturers usually stop offering security updates to phone models after a few years, or even a few months, a significant problem given how long people tend to keep smartphones.
If manufacturers push out an update for the device, all the carriers then have to authorise the update. The final step, of course, is getting people to actually update their phones.
“People see they have an update and know it will take their phone 30 minutes to download it, apply it, and restart the device,” Hazum said. “A lot of people ignore it.”
