What is Cryptojacking? How to Detect & Prevent it?

Cryptojacking is a cyberattack in which a criminal secretly uses your device’s processing power to mine cryptocurrency without your knowledge or consent. Your CPU works at maximum capacity, draining battery life and slowing down the system, while the attacker profits from the mined coins. It operates through malware, malicious websites, and cloud credential theft.

What Is Cryptojacking?

Cryptocurrency mining requires significant computing resources to solve cryptographic problems and validate blockchain transactions. Cryptojackers bypass the cost of this computing power by infecting other people’s devices with mining scripts. The victim bears the cost in electricity, hardware wear, and performance degradation, while the attacker collects the mined cryptocurrency.

Unlike ransomware, cryptojacking is designed to remain hidden for as long as possible, maximising mining revenue before detection. It is one of the fastest-growing categories of cybercrime globally.

How Does Cryptojacking Work?

File-Based Cryptojacking

An attacker delivers a malicious email attachment or a phishing link. When the victim clicks it, two programmes are automatically downloaded: the visible payload (e.g., a document or utility) and a hidden crypto mining programme that runs in the background on every system restart. This method is similar to standard malware delivery.

Browser-Based Cryptojacking

JavaScript mining code is embedded in a compromised website, WordPress plugin, or ad network. When a visitor loads the page, the script automatically launches crypto mining in their browser tab, using their CPU without any file download. The mining stops when the tab is closed but can be hidden in pop-unders that remain open after the main window is closed.

Cloud-Based Cryptojacking

Attackers steal API keys or cloud account credentials, then deploy mining scripts on the victim’s cloud infrastructure. This is particularly damaging for businesses because cloud computing bills can escalate to hundreds of thousands of rupees before the attack is detected.

How to Detect Cryptojacking?

• Device overheating — Sustained CPU loads from mining generate significant heat. If your device is unusually hot during normal browsing, cryptomining may be occurring.
• Performance degradation — Systems running mining scripts exhibit significantly slower response times, as mining consumes 80–95% of available CPU resources.
• CPU usage spikes — Open Task Manager (Windows) or Activity Monitor (Mac) and watch for unexplained processes consuming high CPU. Legitimate websites rarely cause sustained CPU usage above 10%.
• Battery draining rapidly — On mobile devices and laptops, mining accelerates battery discharge dramatically.
• Higher electricity bills — Sustained mining on desktop computers increases power consumption noticeably.

How to Protect Yourself from Cryptojacking?

• Install a reputable antivirus with cryptomining detection — Modern endpoint security solutions include behavioural detection for crypto mining scripts.
• Use a browser extension that blocks mining scripts — Extensions like NoCoin or MinerBlock identify and block known cryptomining JavaScript libraries.
• Disable JavaScript in the browser for untrusted sites — Browser-based cryptojacking requires JavaScript execution. Blocking it on suspicious sites prevents script execution.
• Block ad networks known to serve mining scripts — Ad blockers can prevent malicious ad injections that deliver mining code.
• Keep all software and OS updated — Cryptojacking exploits known vulnerabilities in outdated software. Apply patches promptly.
• Monitor cloud resource usage — Set billing alerts and CPU usage alerts on cloud platforms to detect unusual compute spikes that may indicate credential compromise.
• Never click on phishing links or email attachments — File-based cryptojacking depends on user interaction. See anti-phishing protection for related guidance.

How to Report Cryptojacking in India?

• Call the National Cyber Crime Helpline 1930 to report the incident.
• File a complaint at cybercrime.gov.in with evidence of the malicious script or unauthorised cloud access.
• For cloud-based cryptojacking, notify your cloud service provider’s security team immediately to revoke compromised credentials.

For professional malware assessment and cryptojacking removal, contact cyber expert Anuraag Singh.