In the digital age, cybercrime has evolved far beyond viruses that crash computers or hackers who steal personal data. One of the most stealthy and underestimated threats today is cryptojacking—a form of cybercrime that quietly hijacks your device’s computing power to generate cryptocurrency for criminals, often without you ever realizing it.
Unlike ransomware or identity theft, cryptojacking does not announce itself. There is no ransom note, no missing files, and often no obvious sign of intrusion. Instead, it operates silently in the background, slowly draining system resources, electricity, and productivity—all for someone else’s profit.
As cryptocurrency mining has grown more competitive and costly, cryptojacking has emerged as an illicit shortcut. This article explains what cryptojacking is, how it works, why it exists, how it affects individuals and organizations, and what you can do to protect yourself.
Cryptojacking: Meaning and Definition
Cryptojacking is a type of cybercrime in which hackers secretly use another person’s device—such as a computer, smartphone, tablet, or server—to mine cryptocurrency without the owner’s knowledge or consent.
The term combines “cryptocurrency” and “hijacking.” At its core, cryptojacking is about stealing computing power. Instead of investing in expensive hardware and paying massive electricity bills to mine digital coins, cybercriminals offload those costs onto unsuspecting victims.
What makes cryptojacking particularly dangerous is its stealth. The goal is not to destroy systems or steal data, but to remain hidden for as long as possible, quietly generating income in the background.
A Brief Primer: How Cryptocurrency Mining Works
To understand cryptojacking, it helps to understand cryptocurrency mining.
Most cryptocurrencies operate on a distributed system called a blockchain—a public ledger that records all transactions. To add new transactions to this ledger, the network relies on participants to perform complex mathematical calculations.
These calculations:
- Require significant computing power
- Consume large amounts of electricity
- Are rewarded with cryptocurrency
People or organizations that provide this computing power are known as miners.
For large cryptocurrencies like Bitcoin, mining is now dominated by industrial-scale operations running specialized hardware in massive data centers. According to estimates, the Bitcoin network alone consumes tens of terawatt-hours of electricity annually—comparable to the energy use of entire countries.
For cybercriminals, this creates a problem: mining can be profitable, but only if you can absorb enormous upfront and operational costs.
That is where cryptojacking comes in.
Why Cryptojacking Exists
Cryptojacking is essentially a cost-avoidance strategy.
Instead of:
- Buying mining hardware
- Paying electricity bills
- Maintaining infrastructure
Cybercriminals infect thousands—or even millions—of devices and use their combined processing power to mine cryptocurrency. Each individual device contributes only a small amount, but at scale, the returns can be significant.
The cryptocurrency most commonly mined through cryptojacking is Monero, a privacy-focused coin. Monero is popular with criminals because:
- Transactions are difficult to trace
- It can be mined efficiently on standard CPUs
- It offers greater anonymity than Bitcoin
How Cryptojacking Works
At a technical level, cryptojacking involves planting malicious code on a victim’s device. That code then runs in the background, using the device’s processor to perform mining calculations and sending the results back to a server controlled by the attacker.
There are two primary methods used by cryptojackers.
1. Malicious Downloads and Phishing Attacks
In this approach, attackers trick users into installing cryptomining malware directly onto their devices.
Common tactics include:
- Phishing emails with malicious links or attachments
- Trojan software disguised as legitimate apps
- Fake updates or cracked software downloads
Once installed, the cryptojacking malware embeds itself into the operating system and begins mining continuously, often launching automatically when the device starts.
Because the software is designed to be discreet, it usually limits how much processing power it uses—just enough to generate cryptocurrency without immediately alerting the user.
2. Browser-Based Cryptojacking (Drive-By Mining)
The second method does not require installing traditional malware. Instead, it relies on JavaScript code embedded in websites or online advertisements.
When a user visits an infected site:
- The cryptomining script automatically runs in the browser
- The device begins mining cryptocurrency as long as the page is open
- In malicious cases, hidden pop-under windows keep running even after the user thinks the browser is closed
This method became especially widespread with services like Coinhive, which provided ready-made scripts for Monero mining. While Coinhive initially marketed its service as an alternative to advertising, it was widely abused by hackers who injected scripts into compromised websites without permission.
Although Coinhive shut down in 2019 following legal and regulatory pressure, browser-based cryptojacking has not disappeared—it has simply evolved.
What Cryptojacking Does to Victims
Unlike ransomware or spyware, cryptojacking does not typically steal files or personal data. However, that does not make it harmless.
For Individual Users
Victims may experience:
- Slower system performance
- Frequent freezing or crashes
- Overheating devices
- Rapid battery drain on laptops and phones
- Increased electricity consumption
Over time, excessive strain can reduce the lifespan of hardware components, especially processors and batteries.
For Businesses and Organizations
The impact can be far more serious.
Cryptojacking in corporate environments can lead to:
- Higher energy bills
- Reduced productivity
- Increased IT support and troubleshooting costs
- Network congestion
- Damage to servers and critical infrastructure
Some cryptomining malware includes worm-like capabilities, allowing it to spread laterally across networks and infect additional systems. This makes detection and removal significantly more difficult.
High-Profile Cryptojacking Incidents
Cryptojacking has affected some of the world’s most recognizable organizations, underscoring how pervasive the threat can be.
- Microsoft Store (2019): Several apps were discovered mining cryptocurrency in the background of users’ devices. They were eventually removed after investigation.
- Los Angeles Times (2018): Cryptojacking code was found embedded in the newspaper’s Homicide Report webpage, quietly mining Monero from visitors’ computers.
- European Water Utility (2018): Hackers infiltrated an industrial control system, impairing operations by diverting resources to cryptomining—one of the first known cases involving critical infrastructure.
- YouTube Ads (2018): Cryptomining scripts were delivered through Google’s DoubleClick advertising platform, affecting users worldwide.
- MikroTik Routers (2018): Over 200,000 routers in Brazil were compromised, injecting cryptomining code into web traffic at scale.
These cases illustrate a key point: cryptojacking does not only target careless individuals. Even major platforms and essential services can be affected.
Is Cryptojacking Increasing or Declining?
There is ongoing debate about whether cryptojacking is on the rise or in decline.
Factors that have reduced cryptojacking include:
- Increased law enforcement scrutiny
- Improved browser protections
- The shutdown of major cryptomining script providers
However, cryptojacking activity still tends to rise when cryptocurrency prices surge. As long as mining remains profitable and attackers can stay hidden, the incentive remains strong.
Rather than disappearing, cryptojacking has become more sophisticated—using better obfuscation, adaptive resource usage, and hybrid delivery methods.
How to Detect Cryptojacking
Because cryptojacking is designed to be stealthy, detection can be challenging. Still, there are warning signs.
1. Decreased Performance
If your device suddenly becomes sluggish, crashes frequently, or struggles with basic tasks, cryptojacking could be one possible cause—especially if no legitimate applications explain the slowdown.
2. Overheating
Cryptomining is resource-intensive. If your laptop fan is constantly running at high speed or your phone becomes unusually hot, something may be consuming excessive processing power.
3. High CPU Usage
Checking your system’s CPU usage through tools like Task Manager or Activity Monitor can reveal suspicious activity—particularly if usage spikes when visiting simple websites or running no demanding programs.
Be aware that advanced cryptojacking scripts may disguise themselves as legitimate processes to avoid detection.
How to Protect Yourself Against Cryptojacking
While no defense is perfect, a layered approach significantly reduces risk.
Use Reputable Security Software
A comprehensive cybersecurity solution can detect cryptomining malware, block malicious scripts, and alert you to unusual activity.
Keep Systems Updated
Regularly install operating system and application updates. Many cryptojacking attacks exploit known vulnerabilities that patches are designed to fix.
Use Browser Extensions
Specialized extensions like miner blockers can prevent cryptomining scripts from running in your browser.
Install Ad Blockers
Since many cryptojacking scripts are delivered through malicious ads, ad blockers add an extra layer of protection.
Be Cautious Online
Avoid clicking suspicious links, downloading unverified software, or visiting questionable websites. Phishing remains one of the most common entry points.
Monitor Network Activity
For organizations, monitoring unusual traffic patterns and CPU usage across systems can help identify cryptojacking early.
Why Cryptojacking Should Be Taken Seriously
At first glance, cryptojacking may seem like a minor offense—after all, no files are stolen, and no ransom is demanded. But this view underestimates the harm.
Cryptojacking:
- Exploits resources without consent
- Increases operational and energy costs
- Can damage hardware
- Often indicates broader security weaknesses
- Funds criminal enterprises
In corporate and critical infrastructure environments, it can disrupt operations and expose systems to more serious attacks.
The Bigger Picture
Cryptojacking highlights a broader reality of the digital economy: as new technologies create opportunities, they also create new forms of exploitation.
Cryptocurrency itself is not the problem. The issue lies in how criminals abuse emerging technologies faster than defenses and regulations can keep pace.
As long as digital currencies retain value and mining remains computationally intensive, cryptojacking will remain an attractive option for cybercriminals.
Final Thoughts
Cryptojacking is one of the most silent yet pervasive cyber threats of the modern era. It does not announce itself with alarms or threats, but instead works patiently, siphoning value from devices and organizations around the world.
Understanding how cryptojacking works—and how to defend against it—is now an essential part of digital literacy. Whether you are an individual user or a large organization, awareness, vigilance, and proactive cybersecurity measures remain the best defense against a crime that thrives on invisibility.
In a world increasingly powered by computation, even your idle processing power has value—and someone else may be trying to steal it.