Jamf Blog
A computer processor on top of a keyboard
October 28, 2019 by Liarna La Porta

How do I know if I’ve been cryptojacked?

Cryptojacking, the unauthorized use of a computer to mine cryptocurrency, is an increasingly common threat. How do you spot the warning signs, and how do you prevent cryptojacking attempts?

What is cryptojacking?

Cryptojacking is the unauthorized use of someone else’s computer to mine cryptocurrency. The crypto mining code works in the background as unsuspecting victims use their computers normally.

A smartphone running Mobile Miner alongside icons of different cryptocurrencies

What are the symptoms?

A few signs of cryptojacking include:

  • Device heating up
  • Laptop making loud whirring noises
  • Battery draining faster than usual
  • Impaired device performance – slowing down, crashing, etc.

What are the causes?

Currencies such as Bitcoin, Ethereum and Monero are all continually "mined" by using distributed computing resources to work out problems that generate "hashes." Anyone can use their machines to process new coins in this way, but with cryptojacking, website owners and app developers are able to harness the CPU of their audience instead, earning them cryptocurrency in the process.

Hackers cryptojack your device by either getting you to click on a malicious link in an email that loads crypto mining code on your device, or by infecting a website or online ad with JavaScript code that auto-executes once loaded in your browser.

Another image of a smartphone alongside cryptocurrency icons

What’s the treatment for cryptojacking?

So you’ve seen the signs of cryptojacking on your device, what now?

  • Close and block the website running the script
  • Update and purge browser extensions

Prevention

The best remedy is prevention. Stay safe from cryptojacking by following this guidance:

  • Watch out for phishing-type attempts to load scripts onto your device
  • Install an ad-blocker extension for your web browsers
  • Routinely check your browser extensions for anything suspicious and keep them up to date

No matter how hard you try to educate yourself and your team, it’s inevitable that some attempts will slip through the net. To stay ahead of the attacker it’s imperative to have a security solution in place which is able to intercept traffic to phishing sites, stopping the threat at its source. Learn more about Jamf Threat Defense and how it can help today.

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