A type of Android malware that's been targeting banking users worldwide since March has resurfaced with advanced obfuscation methods, masquerading as a legitimate application on the Google Play store with more than 10 million downloads, researchers have found.
Godfather is a banking Trojan that is best known for targeting banking users in European countries, but its latest activity shows an increased sophistication in its ability to fly under the radar of common malware-detection methods, researchers from Cyble Research & Intelligence Labs (CRIL) said in a blog post on Dec. 20.
Once it's successfully installed on a victim's device, Godfather initiates a series of typical banking Trojan behaviors, including stealing banking and crypto-exchange credentials, the researchers said. But it also steals sensitive data such as SMSs, basic device details — including data from installed applications — and the device's phone number, and it can perform a number of nefarious actions silently in the background.
"Apart from these, it can also control the device screen using VNC [virtual network computing], forwarding incoming calls of the victim's device and injecting banking URLs," the Cyble researchers wrote.
The latest sample of Godfather that researchers discovered was encrypted using custom encryption techniques that could evade detection by common antivirus products — a new tactic of the threat actors behind the malware, the researchers said.
Targeting Businesses & Consumers
Upon further examination, the researchers found that the malware was using an icon and name similar to the legitimate Google Play app MYT Music, which already has logged more than 10 million downloads. Indeed, threat actors often hide malware on Google Play, despite Google's best efforts in the last several years to keep bad apps off its store before users are affected by it.
MYT Music was written in the Turkish language and thus researchers assume the Godfather sample they discovered is targeting Android users in Turkey. However, they suspect other versions of the malware continue to be active and targeting banking users worldwide.
Though banking Trojans tend to affect consumers more than the enterprise, business users are still at risk because they use their mobile devices at work and may even have business apps and data stored on their devices. For this reason, enterprise users should be especially wary of downloading apps from the Internet or opening any links received via SMS or emails delivered to a mobile phone, the researchers said.
Google Play has removed the app, but those with it installed are still at risk.
How Godfather Pulls Victims' Strings
Once it's installed on an Android device, Godfather requests 23 different permissions from the device, abusing a number of them to gain access to a user's contacts and the state of the device, as well as information related to the user account. It also can write or delete files in external storage and disable the keylock and any associated password security, the Cyble researchers said.
Godfather can successfully do money transfers from a hacked device through its ability to initiate phone calls through Unstructured Supplementary Service Data (USSD) that don't require use of the dialer user interface, and thus don't need the user to confirm the call, they said.
The malware also extracts sensitive user data from the device — including application key logs — that can be sent back to a command-and-control (C2) server, which also sends Godfather a command that forwards any incoming calls the victim receives to a number provided by the threat actor, the researchers said.
Godfather then harvests credentials: It creates an overlay window in the OnAccessibilityEvent method and injects HTML phishing pages via a separate command from C2, the server URL of which is from a Telegram channel, hxxps://t[.]me/varezotukomirza, the researchers said.
Once it completes its malicious activity, Godfather receives a "killbot" command from C2 to self-terminate, they added.
Avoiding Being Whacked by Godfather
The most common way to avoid downloading mobile app malware is to download and install software only from official app stores such as Google Play or Apple, the conventional wisdom goes.
However, as this instance proves, malware can lurk in official app stores too, so "practicing basic cyber-hygiene across mobile devices and online banking applications effectively prevents such malware from compromising your devices," the researchers noted in the post, including using a reputable antivirus and Internet security software package on connected devices to ensure anything downloaded is free from malware.
Also, advanced anti-detection methods like the ones the threat actors behind Godfather are using can make even downloading what look like legitimate apps tricky, they said. To further protect themselves, users can utilize strong passwords and enforce multifactor authentication on devices wherever possible, making it more difficult for threat actors to crack into their accounts.
Android device users also should ensure that Google Play Protect is enabled on their devices for further security protection, the Cyble researchers added.
All mobile device users also should enable biometric security features such as fingerprint or facial recognition for unlocking the mobile device and using apps, where possible, and be especially careful when enabling permissions on devices, especially if an app has not been verified by a reputable provider, they added.