Most Android users will never have to deal with malware apps on their devices, or at least not as long as they don’t download potentially malicious apps from third-party app stores. But there are people who can’t get apps from Google Play or choose to ignore the official app store, and they are more exposed to malicious apps.

One malware app was just updated with a feature that can block calls to customer support numbers belonging to certain banks so that affected users can’t stop fraudulent transactions.

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Android.Fakebank is a malware app Symantec first discovered in October 2013. What the app does is to replace any banking apps on a device with fraudulent versions that let the attacker access the victim’s bank account and transfer funds.

A new version that was released in March includes the call blocking feature mentioned above. When a victim tries to call the customer service of a bank to stop a fraudulent transaction, the malware blocks that call. Sure, the target can contact the bank in person, using a different handset, or by email. But until that happens, the hackers still have access to that bank account.

Currently, Android.Fakebank.B affects users in South Korea and Russia, blocking only phone numbers that belong to banks in these regions.

Again, the best way to avoid malware on Android is to stick to downloading only apps from the Google Play store. Monitoring your bank accounts for fraudulent activity on a constant basis might also be a good idea.