Crypto-currency Mining Apps Discovered in Microsoft Store

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Crypto-currency Mining Apps Discovered in Microsoft Store

Security researchers at Symantec claim to have discovered eight apps in the Microsoft Store which, if downloaded, can use the victim’s computer to mine crypto-currency.

Only There For A Short Time Last Year

The suspect apps are reported to have only been on the Microsoft Store for a short time between April and December 2018, but it is thought that they still managed to achieve significant download numbers, as indicated by nearly 1,900 ratings posted for the apps.

Which Apps?

The suspect apps, in this case, are Fast-search Lite, Battery Optimizer (Tutorials), VPN Browsers+, Downloader for YouTube Videos, Clean Master+ (Tutorials), FastTube, Findoo Browser 2019, and Findoo Mobile & Desktop Search apps.  These apps have now been removed from the Microsoft Store,

What Is Crypto-currency Mining?

‘Crypto-currency mining’ involves installing ‘mining script’ code such as Coin Hive into multiple web pages without the knowledge of the web page visitor or often the website owner. Multiple computers then join their networks so that the combined computing power can enable mathematical problems to be solved. Whichever scammer is first to solve these problems is then able to claim/generate cash in the form of crypto-currency, hence mining for crypto-currency.

Crypto-currency mining software tends to be written in JavaScript and sends any coins mined by the browser to the owner of the web site. If you visit a website where it is being used (embedded in the web page), you may notice that power consumption and CPU usage on your browser will increase, and your computer will start to lag and become unresponsive. These slowing, lagging symptoms will end when you leave the web page.

Mining For Monero

In the case of the eight suspect apps, they had been loaded with a script that had been designed to mine the ‘Monero’ crypto-currency.  Monero, which was created in April 2014 is a decentralised cryptocurrency that uses an obfuscated public ledger.  This means that anybody can broadcast or send transactions, but no one outside can tell the source.


The secret mining element of the eight suspect apps worked by triggering Google Tag Manager (GTM) in their domain servers as soon as they were downloaded.  The GTM, which was shared across all eight apps, enabled them to fetch a coin-mining JavaScript library, and the mining script was then able to use most of the computer’s CPU cycles to mine Monero.

GTM – Legitimate

GTM is usually a legitimate tool that is designed to enable developers to inject JavaScript dynamically into their applications.  In this case, however, it had been used as a cloak to conceal the malicious purpose of the apps.

Not The First Time

This is not the first time that suspect apps have been discovered lurking in popular, legitimate app stores. Back in January, for example, security researchers discovered 36 fake and malicious apps for Android that can harvest a user’s data and track their location, masquerading as security tools in the trusted Google Play Store. The apps, which had re-assuring names such as Security Defender and Security Keeper, were found to be hiding malware, adware and even tracking software.

Also, back in November 2017, a fake version of WhatsApp, the free, cross-platform instant messaging service for smartphones, was downloaded from the Google Play store by more than one million unsuspecting people before it was discovered to be fake.

What Does This Mean For Your Business?

This is not the first time that apps which perform legitimate functions of the surface and are available from trusted sources such as Microsoft store have been found to have hidden malicious elements, in this case, mining scripts.  The increased CPU usage and slowing down of computers caused by mining scripts waste time and money for businesses, and the increasingly sophisticated activities of crypto-jackers and other cyber-criminals, combined with a global shortage of skilled cyber-security professionals to handle detection and response have left businesses vulnerable to this kind of hidden app-based threat.

Although the obvious advice is to always check what you are downloading and the source of the download, the difference between fake apps and real apps can be subtle, and even Microsoft and Google don’t always seem to be able to detect the hidden aspects of some apps.

The fact that many of us now store most of our personal and business lives on our smartphones makes reports such as these more alarming. It also undermines our confidence in (and causes potentially costly damage to) the brands that are associated with such incidents e.g. the reputation of Microsoft Store.

Some of the ways that we can try to protect ourselves and our businesses from this kind of threat include checking the publisher of an app, checking which permissions the app requests when you install it, deleting apps from your phone that you no longer use, and contacting your phone’s service provider or visit the High Street store if you think you’ve downloaded a malicious/suspect app.

Also, if you are using an ad blocker on your computer, you can set it to block a specific JavaScript URLs related to crypto-mining, and some popular browsers also have extensions that can help e.g. a browser extension called ‘No Coin’ is available for Chrome, Firefox and Opera (to stop Coin Hive mining code being used through your browser).  Maintaining vigilance for unusual computer symptoms, keeping security patches updated, and raising awareness within your company of current crypto-currency mining threats and scams and what to do to prevent them, are just some of the other ways that you can maintain a basic level of protection for your business. 

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