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Don't get run over by drive-by mining

BY eSentire Threat Intel

November 23, 2017 | 3 MINS READ

Threat Intelligence

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Drive-by Mining is exploding in popularity, as it’s being adopted by both legitimate websites and criminal organizations. Drive-by Mining or Cryptojacking is when a website uses the CPU power of a site visitor to perform the complex mathematical equations involved in ‘mining’ cryptocurrencies, such as Monero or Bitcoin. When the unsuspecting user opens a website running the JavaScript miner, their browser will continuously ‘mine’ until they leave the site. At its best, this practice is a non-intrusive way for websites to produce revenue without relying on ads; at its worst, drive-by mining is a way for criminal organizations to raise funds while your devices are exploited.

Danger Ahead

At first glance drive by mining may not seem that bad, but taking advantage of the visitor’s CPU resources to mine cryptocurrencies can have serious implications. Criminals have quickly adapted this technology, demonstrating that drive-by mining can be used as an easy source of income. High traffic websites with security misconfigurations are targeted for code injection. Then, without the consent of the website owner or the individuals visiting the website, their resources are used to help fund criminal organizations.

Cryptocurrency mining can also be an extremely labor intensive task for devices. The code has been known to make systems freeze or crash, causing data and time loss. If the actor implementing the miner is especially thoughtless or malicious, the code can be set to use all available CPU power. This is known as Code Full Throttle and will not only cause your device to fail but has the potential to damage your hardware.

Am I a Victim?

Figure 1 - Coinhive asking for user permssion to run the mining script.

Unless the hosting websites asks for user permission to run the mining script (which services such as Coinhive have began to do – Figure 1), it may not be immediately clear that you are mining a cryptocurrency. The are several tell-tale signs that the web-page you are on is using a drive-by mining script: the device will be warmer than normal, the fan noise will increase, the mouse and keyboard may be slow or unresponsive and the device’s general performance could decrease.

Resource monitoring applications are a simple way to tell if a website is running a mining script. If no other applications or tabs are open and the device’s resource use spikes on a web-page, then it is likely that the device is mining for cryptocurrency.

If you still aren’t sure, the website Whorunscoinhive allows users to check URLs for JavaScript miners and has an extensive list of websites that, either knowingly or unwittingly, are exploiting their visitors.

Drive-by Mining is Here to Stay

Since September, the eSentire Threat Intelligence Team has seen a large number of drive-by mining alerts originating from IPs across the world. According to Google Trends, Google searches for the term “Javascript Miner” saw a steep spike on September 16th (Figure 2) and four days later eSentire noticed a drastic increase in cryptocurrency events (Figure 3).

Figure 2 - Google searches for the term “Javascript Miner” saw a steep spike on September 16th

Figure 3 - A drastic increase in cryptocurrency events.

The popularity of drive-by cryptocurrency miners is the result of multiple factors. First off, it is simple to use; the JavaScript can be purchased or rented legally from various vendors, then inserted by an administrator into their website or maliciously inserted into misconfigured websites. This allows even relatively inexperienced cyber-criminals to quickly profit. Secondly, drive-by mining is still a legal grey-area because it is exploiting users for their CPU power but not directly stealing from them. Lastly, drive-by mining is profitable. As long as this activity remains simple, quasi-legal, and profitable, it will continue to be popular.

What can you do?

The eSentire SOC and Threat Intelligence team are continually adding malicious IPs to the eSentire global blacklist (Asset Manager Protect, via esNETWORK) as they’re detected. But there are steps every user can take to minimize the risks associated with unknowingly mining from their browser. There are various chrome applications specifically for blocking websites from using visitors’ CPU power to mine cryptocurrencies. The very popular application AdBlock has implemented a block for drive-by mining in its premium version and various anti-virus programs have already began treating websites using the JavaScript as malicious. Even big name browsers, such as Chrome, are considering blocking the mining JavaScript in future updates.

There is no perfect answers to security questions, but staying aware of the latest threats is half the battle.

eSentire Threat Intel
eSentire Threat Intel Threat Intelligence Research Group

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