Cryptojacking sounds like something out of a sci-fi movie, but it’s a very real threat lurking in the digital world. Imagine your computer quietly being used by someone else to mine cryptocurrency – without your knowledge or permission. That’s cryptojacking in a nutshell. It’s sneaky, it’s harmful, and it’s becoming more common. In this guide, we’ll break down everything you need to know about cryptojacking, how to spot it, and most importantly, defend yourself against it.

Understanding Cryptojacking

What exactly is cryptojacking?

Cryptojacking is like having a digital pickpocket. It’s when hackers secretly install software on your device (computer, phone, or even a server) that drains its power to mine cryptocurrency. Think of cryptocurrencies like Bitcoin – they require complex calculations to be “mined,” and that takes computing power. Instead of buying their own equipment, cryptojackers hijack yours, leaving you with the electricity bill and a sluggish machine.

How cryptojacking works

There are a few ways you can get hit by cryptojacking:

  • Sneaky code on websites: Some websites might have hidden lines of code that hijack your computer’s resources while you’re browsing.
  • Phishing emails: Clicking on an infected link in an email can download cryptojacking malware right onto your device.
  • Compromised apps: Fake or corrupted apps, even on official app stores, sometimes hide cryptojacking software.

Types of Cryptojacking

Browser-based cryptojacking

This is the most common type. Hackers inject lines of JavaScript code into websites. When you visit that site, the code runs in your browser and starts mining cryptocurrency, using your computer’s processing power without your knowledge. The longer you stay on the site, the more they mine.

Malware-based cryptojacking

This is a more insidious attack. You download software that seems harmless, but hidden within it is malware designed to install a crypto miner. This can happen through dodgy free software, fake updates, or opening infected attachments in emails. Once it’s running, it might stay hidden in the background, continuously draining your resources.

Fileless cryptojacking

This type of cryptojacking is tough to spot. Instead of using traditional malware that leaves files on your system, fileless attacks run entirely in your computer’s memory (RAM). They often exploit vulnerabilities in software you already have, leaving little trace and making them harder to detect.

Telltale Signs of Cryptojacking

Slow device performance

Is your computer or phone suddenly feeling sluggish? Apps taking forever to load or websites crawling? Cryptojacking can overload your processor, making everything run much slower than usual.


Cryptojacking makes your device work overtime. If it’s a laptop, it might feel unusually hot on your lap, or the fans might run constantly. Phones and tablets might also feel warmer than usual during normal use.

Spikes in CPU usage

Check your computer’s task manager or activity monitor. Are you seeing constant high CPU usage even when you’re not actively running many programs? That’s a telltale sign that something might be using your computing power in the background.

Increased energy consumption

Cryptojacking means your device is running full-tilt, which translates to higher electricity bills. If you see a sudden unexplained jump in your power usage, it’s worth investigating.

Important Note: These signs don’t automatically mean you’ve been cryptojacked. Other issues could cause similar effects. However, they are strong clues to investigate further.

Dangers of Cryptojacking

Financial losses

The most obvious impact is financial. Higher electricity bills are just the beginning. Cryptojackers are essentially stealing your resources, meaning you pay to power their profit-making operation.

Device damage

Constantly running your device at maximum capacity can wear it out prematurely. Overheating can damage components like your battery, fans, or even the processor itself, potentially shortening the lifespan of your computer or phone.

Security threats

Cryptojacking doesn’t just affect your hardware; it can also open the door to other cyberattacks. The malware used might have other malicious functions or create vulnerabilities that allow hackers to gain access to your system, steal your data, or install even nastier software.

How to Protect Yourself from Cryptojacking

Install a reliable antivirus

A good antivirus program with real-time monitoring can often detect and block cryptojacking malware. Make sure your antivirus is always up to date and running regular scans.

Use an ad blocker

Ad blockers can help prevent cryptojacking scripts hidden within online ads. Browser extensions like uBlock Origin or AdBlock Plus are effective options.

Keep your software updated

Outdated operating systems, browsers, and apps often contain security holes that cryptojackers exploit. Regularly install updates as they become available to patch these vulnerabilities.

Be cautious with browser extensions

Browser extensions can be super useful, but they can also be a weak spot. Only install extensions from trusted sources, and keep an eye on their permissions. If an extension suddenly asks to use a lot of processing power, it may be a red flag.

Monitor device resources

Pay attention to your device’s performance. Get familiar with normal CPU usage patterns, so you can spot unusual spikes. Check your battery health too – if it’s draining more quickly than normal, it could be a warning sign.

What to Do if You Suspect Cryptojacking

Scan your system

Run a full system scan with your antivirus or anti-malware software. If it detects anything suspicious, follow the software’s instructions for removal.

Isolate infected devices

If you think a device is infected, disconnect it from your network immediately. This helps prevent the malware from spreading to other devices.

Seek professional assistance

If you’re not tech-savvy, or the infection seems persistent, it’s best to contact an IT support specialist or cybersecurity professional. They can help identify and remove the cryptojacking malware thoroughly.

Additional Tips

  • Be wary of suspicious links and downloads: Think twice before clicking on links in unsolicited emails or on unfamiliar websites. Never download pirated software or attachments from unknown senders.
  • Train your employees (if applicable): If you run a business, make sure your employees understand the dangers of cryptojacking and basic cyber hygiene practices.


Cryptojacking is a growing threat that exploits the desire for cryptocurrency and our increasing reliance on computing devices. While it might seem less severe compared to data-stealing malware or ransomware attacks, it can cause financial losses, hardware damage, and act as a gateway to further cyberattacks. The stealthy nature of cryptojacking makes it particularly insidious.

Staying safe in this digital landscape requires proactive protection and a healthy dose of skepticism. By following the practices outlined in this guide, you can significantly reduce your risk of falling victim to cryptojackers. Remember, antivirus software, software updates, caution with downloads and links, and vigilance towards your device’s behavior are your allies. If you operate a business, regular cybersecurity training for employees becomes absolutely essential.

Cryptocurrency itself is a fascinating technology with potential for innovation, but cybercriminals will always seek ways to exploit it for their own gains. Staying informed, keeping your defenses up, and being mindful of the resources you share with the digital world are crucial steps for safe and rewarding digital experiences.


  • Can my smartphone be cryptojacked? Absolutely. While less common than on computers, cryptojacking on smartphones and tablets is increasing. The same principles apply: be wary of suspicious downloads and monitor your device’s performance for any unusual spikes in processor usage or battery drain.
  • Am I more at risk if I browse cryptocurrency-related websites? Unfortunately, yes. Websites dealing with cryptocurrency are sometimes targets for cryptojacking scripts, so it’s wise to be extra vigilant. Remember, even legitimate sites can sometimes be unknowingly compromised.
  • How is cryptojacking different from regular cryptocurrency mining? The main difference is consent. Legitimate cryptocurrency mining is done with the user’s knowledge and using their own dedicated resources. Cryptojacking is the unauthorized and often hidden use of someone else’s computer power and electricity.
  • Is it illegal to cryptojack someone? Yes, cryptojacking is considered a form of cybercrime in most jurisdictions. Hackers can face charges for unauthorized access to computer systems, theft of resources, and potentially other offenses depending on the specific circumstances.
  • What if I find cryptojacking code on my own website? This likely means your website has been hacked. Immediately remove the suspicious code and investigate how the breach occurred. Strengthen your website security and inform your visitors about the incident.
  • Can cryptojacking impact large networks (e.g., businesses)? Certainly. A single infected device in a large network can slow down operations and cause increased energy costs. Imagine dozens or even hundreds of hijacked machines – the damage can be significant. Businesses need network-wide security and employee training on cyber awareness.
  • How can I report cryptojacking? If you suspect cryptojacking, you can report it to your local cybersecurity authorities. In the US, you can contact the Internet Crime Complaint Center (IC3).
  • Is cryptojacking ever ethical? Rarely. There have been isolated cases where websites experimented with cryptojacking as an alternative to advertising, with full transparency towards their users. However, this is contentious, and the stealthy, unauthorized form of cryptojacking we mostly see is never ethical.

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