Cryptojacking

Cryptojacking is the unauthorized use of someone else’s computer, phone, or server to mine cryptocurrency for the attacker’s benefit. Mining crypto requires significant computational power to solve complex mathematical puzzles and earn new coins as a reward. Instead of investing in their own hardware and electricity, cryptojackers secretly install malicious software on other people’s devices — or embed mining code in websites — and harvest the processing power without the owner’s knowledge or consent.

The victim typically notices symptoms before they identify the cause: their device runs unusually hot, the battery drains much faster than normal, the fan runs constantly, and the device slows down significantly, even during simple tasks. These symptoms occur because their CPU or GPU is being secretly maxed out for someone else’s financial gain. Unlike ransomware, cryptojacking does not lock your files or make overt demands — it operates silently in the background, making it harder to detect.

Cryptojacking can happen through malicious email attachments, compromised software downloads, or drive-by mining through websites that run JavaScript mining code in your browser while you visit. Keeping software updated, using reputable antivirus and anti-malware tools, using browser extensions that block mining scripts, and being cautious about what you download are the main defenses. The activity is illegal in most jurisdictions but enforcement is difficult because attackers are often anonymous and operate across borders.

Example: Imagine you rent out a warehouse and later discover that the tenant has been secretly running a power-hungry factory inside it 24 hours a day, using your electricity and wearing down the building, without paying for any of it. Cryptojacking is exactly that — someone using your device’s “electricity” and wear to generate profit for themselves while you get nothing but a slower, hotter machine and a higher energy bill.