The bogus antivirus software, dubbed Fakedefender, is the first ransomware Symantec has found for a mobile device.
The Android-targeting malware was found early this month hidden in a variety of apps available in online stores aimed at English speakers in several countries, including the U.S. The software was not seen on Google's official Android store, Google Play.
The ransomware has been downloaded only hundreds of time, so the level of infection is very low, said Vikram Thakur, principal researcher for Symantec Security Response. However, given the immaturity of the malware, it's unlikely the creators, believed to be of Russian origin, were looking for wide distribution.
"The developers of this fake [antivirus] are still in the very early stages of making this compatible with all sorts of [Android] platforms on phones that they intend to target," Thakur said on Friday.
Fakedefender is a type of ransomware that pretends to find malware on a device and then demand that the victim buy a premium version of the bogus antivirus software to remove the malicious apps.
Such ransomware has been used against personal computer users for years, but is unique on mobile devices, Symantec says. Fakedefender is a work in progress because the malware does not steal any personal information and does not connect to a site for victims to pay the $10 the software demands for removing malware.
Why the developers would release such immature software is not known. They could have released the software to do some testing, or "they just released it by mistake," Thakur said.
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For now, the application is primarily an irritant for the victim. Because of its instability, the malware can cause the Android operating system to crash or it can lock up the smartphone so no application, including the malware, will work.
"Even in its current form, it is malicious enough that it is going to cause a lot of headaches for end users who get infected," Thakur said.
Removing the software is not easy and goes beyond the technical expertise of most smartphone users. Essentially, there are two options. People can plug the phone into a computer and remove the app manually, or they can do a hard reset to bring the OS back to its factory settings.
Symantec said it believes the number of fake antivirus software developed by cybercriminals will be small in comparison to other forms of malware. Nevertheless, the company says it will eventually become commonplace because of the amount of money cybercriminals can make.
While other malware can bilk from a few cents to a few dollars per victim, ransomware developers will demand much more to free a person's computer. In some countries, cybercriminals demand more than $100 to free a person's personal computer.
"The numbers are not going to be equal to what we see in the PC space, but we expect this to be a large enough problem that it becomes common knowledge for people to know someone who has been infected or impacted by one of these things," Thakur said.