Image: iStock

Android malware capable of accessing smartphone users' location and sending it to cyberattackers remained undetected in the Google Play store for three years, according to a security company.

Discovered by IT security researchers at Zscaler, the SMSVova Android spyware poses as a system update in the Play Store and was downloaded between one million and five million times since it first appeared in 2014.

The app claims to give users access to the latest Android system updates, but it's actually malware designed to compromise the victims' smartphone and provide the users' exact location in real time.

Researchers become suspicious of the application, partly because of a string of negative reviews complaining that the app doesn't update the Android OS, causes phones to run slowly, and drains battery life. Other indicators that led to Zscaler looking into the app included blank screenshots on the store page and no proper description for what the app actually does.

Indeed, the only information the store page provided about the 'System Update' app is that it 'updates and enables special location' features. It doesn't tell the user what it's really doing: sending location information to a third party, a tactic which it exploits to spy on targets.

Image: Zscaler

Once the user has downloaded the app and attempts to run it, they're immediately met with a message stating "Unfortunately, Update Service has stopped" and the app hides its run icon from the device screen.

But the app hasn't failed: rather, the spyware sets up a feature called MyLocationService to fetch the last known location of the user and set it up in Shared Preferences, the Android interface for accessing and modifying data.

The app also sets up an IncomingSMS receiver to scan for specific incoming text messages which contain instructions for the malware. For example, if the attacker sends a text saying "get faq" to the device, the spyware responds with commands for further attacks or passwording the spyware with 'Vova' -- hence the name of the malware.

Zscaler researchers suggest that the reliance on SMS to start up the malware is the reason that antivirus software failed to detect it at any point during the last three years.

Once the malware is fully set up, it's capable of sending the device location to the attackers -- although who they are and why they want the location information of regular Android users remains a mystery.

The app hasn't been updated since December 2014, but it's still infected hundreds of thousands of victims since then and, as researchers note, the lack of an update doesn't mean the functionality of the malware is dead.

What's interesting, however, is that SMSVova appears to share code with the DroidJack Trojan, indicating that whoever is behind the malware is an experienced actor who seems to specialise in targeting Android systems.

The fake system update app has now been removed from the Google Play store after Zscaler reported it to the Google security team, although that doesn't do anything to help the people who've downloaded it over the last three years and who may still be compromised by SMSVova.

While Google keeps the vast majority of its 1.4 billion Android users safe from malware, there are repeated instances of malware and even ransomware which manage to sneak past its defences and into the official Android store.

ZDNet has contacted Google for comment on why the malware was in the Play Store for three years, but is yet to receive a reply.

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