{ Pablo Díaz }

i've been hacked and traced the malware's wallet to see how much money they actually made from this new exploit (if you use Next.js/React, READ THIS!) I woke up to a terrifying email from Hetzner: "Netscan Detected." my server was blocked and a botnet was using my IP to attack others i dug into the logs and what I found the anatomy of the attack: 1) The Symptoms: I logged into htop and saw the mess: - CPU usage: 361% - A process named ./3ZU1yLK4 running wild - Random connections to an IP in the Netherlands my server wasn't serving my app anymore; it was mining crypto for someone else! 2) The Culprit: It wasn't a random SSH brute force. It was inside my Next.js container the malware was sophisticated it renamed itself nginxs and apaches to look like web servers it even had a "killer" script that hunted down other hackers' miners to kill the competition 3) The "Root" Cause (literally): Probably the recent React/Next.js CVE-2025-66478 exploit was the entry point (my project was running on "next": "15.5.4", behind cloudflare dns, but their recent fix didn't work apparently) but the fatal error was mine: my Docker container was running as ROOT Coolify deploys like this automatically when using Nixpacks, and I never changed it... so because of USER root, the malware could install cron, systemd, and persistence scripts to survive reboots meaning, it was able to infect my whole server, from a single Next.js docker! 4) The Forensics: I ran docker diff on the container - the hacker didn't just run a script, they installed a whole toolset.. - /tmp/apaches.sh (The installer) - /var/spool/cron/root (The persistence) - /c.json (The wallet config) 5) The Fix: I killed the container, scrubbed the host, and extracted the malware for analysis. but the real fix is in the Dockerfile. if you are deploying Node/Next.js, DO NOT use the default (root), you must: - RUN adduser --system nextjs - USER nextjs if you have Docker on ROOT and didn't update the exploited react version, you'll be hacked soon check your containers NOW. Run: docker exec id (or get the full list first: docker stats --no-stream) If it says uid=0(root), you are one vulnerability away from being a crypto-miner host. (it's easy to notice when hacked, it will be a command running on the top CPU%, using all your hardware resources) 6) The Money: I dug deeper and recovered the config file (c.json) - Wallet: A Monero (XMR) address: 831abXJn8dBdVe5nZ*** - Pool: auto.c3pool . org and ofc i tracked the hacker’s wallet on the mining pool 7) The Scale: My server wasn't alone. It was just 1 of 415 active zombies in this botnet they are burning the CPU of 400+ cloud servers... to earn... guess how many millions? $4.26/day on the image attached you can see: "Total Paid: 0.00", meaning this campaign just started. I caught them on Day 1. i also tracked back the server where they hosted the malware, and by inspecting the code, I found several comments in Chinese, so I guess that's their origin im rebuilding from scratch on a fresh VPS. the lesson was expensive, but at least I caught it before the hosting nuked my account permanently... PS: I have the IP for all the other machines mining with that malware, not sure how I can help them, but feel free to contact me if ur doing infosec stay safe