Cryptojacking is a form of cyberattack where hackers secretly use your device's processing power to mine cryptocurrency. Rather than stealing data or demanding ransom, attackers install malware that runs silently in the background, consuming your CPU or GPU resources to solve complex mathematical problems and earn cryptocurrency for the attacker.
This happens across devices ranging from personal computers and smartphones to web servers and Internet of Things hardware. The malware often spreads through compromised websites, malicious email attachments, or vulnerable software. Some attackers inject mining scripts directly into websites, which execute code in visitors' browsers without their knowledge.
Why it matters: Cryptojacking degrades your device's performance, increases electricity consumption, and reduces hardware lifespan. It's particularly costly for businesses running servers. Victims often notice slow performance, excessive battery drain, or unexplained high CPU usage before realising they're infected.
Common indicators:
- Fans running constantly at high speed
- System sluggishness during normal use
- Unexpected increases in electricity bills
- Overheating, especially on laptops
- Browser becoming unresponsive
Protection: Keep security software updated, run regular malware scans, disable JavaScript in your browser if you don't need it, and use ad blockers that also catch mining scripts. For businesses, monitor CPU usage patterns and network traffic for suspicious activity. Update software promptly to patch vulnerabilities attackers exploit.
Unlike ransomware, cryptojacking operates quietly, making detection harder. Many victims remain unaware they're compromised for months.