Picture this. You add a new chat widget or analytics tag to your site. Everything works fine at first, but then the site feels a bit slower. Your servers are running hotter than usual, fans are spinning, and your cloud bill is climbing. Nothing in your own code changed.
That’s often how people run into CryptoJack.
Cryptojacking is when attackers hijack your systems or your users’ browsers to mine cryptocurrency. There’s no ransom note, no alert on the screen. It just runs in the background, quietly draining your resources while someone else collects the rewards.
How CryptoJack Slips In
Websites today are full of third-party code. Analytics, chat pop-ups, A/B testing, ad networks. Every one of those scripts is another door into your site. If one of them gets compromised, attackers can add a mining script right alongside the code you trust.
In a browser, this means your visitors are doing the mining work. Their CPU usage jumps, the fan kicks in, and the page feels sluggish. On the server side, malicious packages or integrations can plant miners that run nonstop in the background. The effect is the same. Someone else is making money, you are paying the bill.
Why It Matters
At first it might not seem like a big deal. Nobody stole data, nobody locked your files. But the costs are real. Pages load slower, users drop off, cloud costs creep up. In elastic environments, attackers can even spin up more resources, all at your expense.
The bigger issue is that cryptojacking shows there’s already a gap in your defenses. If someone can sneak in mining code, they could use that same path for credential theft, ransomware, or worse.
How to Keep CryptoJack Out
The fixes are not fancy. They are mostly about good hygiene and visibility.
- Patch often. A lot of mining campaigns rely on old bugs that never got fixed.
- Limit third-party code. Use Content Security Policy (CSP) and Subresource Integrity (SRI) to stop untrusted scripts from running unnoticed.
- Use SaaS security services. These tools watch your site for changes, scan third-party scripts, and catch suspicious behavior. They are especially useful if your site runs a lot of external code.
- Monitor performance. Set a baseline for CPU and memory usage. If something spikes without reason, take a look.
- Endpoint protection. Many security tools today can spot common mining patterns and block them.
- Keep people alert. A laptop that suddenly sounds like a jet engine might be running more than just Chrome.
Also keep an eye on cloud billing. Cryptojacking loves elastic environments where costs can grow quickly without limits.
Final Thoughts
CryptoJack is quiet by design. It hides in normal traffic, slips in through trusted scripts, and drains resources slowly so you don’t notice. That makes it easy to ignore until the impact adds up.
If your site or servers are suddenly running harder for no good reason, don’t brush it off. It might not just be a bug or heavy load. It could be someone else using your compute power to mine coins.
Further Reading
For anyone who wants to dive deeper, here are a few good studies and reports: