Has My Computer Been Hacked? Warning Signs and What to Do

The common warning signs

Several signs suggest a computer may be compromised. Watch for: pop-up ads appearing outside the browser, your homepage or search engine changing on its own, new programs or toolbars you did not install, your antivirus being disabled, the computer running slowly or working hard while idle, and your cursor or programs acting on their own.

Account-side signs are just as important: friends receiving messages you did not send, being locked out of accounts, password-reset emails you did not request, or unfamiliar logins and transactions. Any one of these warrants attention; several together strongly suggest a compromise that needs acting on.

Signs that point to account compromise, not the computer

It is worth distinguishing between a hacked computer and a hacked account, because they need different responses. If your email or social media is sending messages you did not write, or you are seeing logins from unfamiliar locations, your account may be compromised even if your computer is clean — often through a leaked or reused password rather than malware.

Many people assume their computer is hacked when in fact a password leaked in a data breach elsewhere. The fix there is account-focused: change passwords and enable two-factor authentication. Knowing which you are dealing with — device or account — helps you respond effectively rather than chasing the wrong problem.

Step 1: Disconnect from the internet

If you believe your computer is compromised, disconnect it from the internet straight away by turning off Wi-Fi or unplugging the network cable. This cuts off any remote access and stops malware communicating out or downloading more. It contains the situation while you work through securing things.

Keeping the machine offline during clean-up also prevents further data being sent out. You can reconnect briefly when you need to update security software, then disconnect again. This simple step limits the damage an active compromise can do.

Step 2: Secure your accounts from a clean device

Using a different device you trust — a phone or another computer — change the passwords on your most important accounts, starting with your primary email, since it is the key to resetting everything else. Then your banking, then other sensitive accounts. Do not do this from the suspect computer, as it may be recording what you type.

Turn on two-factor authentication everywhere you can, so that even a stolen password is not enough for an attacker to get back in. If money is involved, contact your bank promptly. Securing your accounts is often more urgent than cleaning the computer, because that is where real harm happens.

Step 3: Scan and clean the computer

To clean the machine, boot into Safe Mode and run a full scan with Windows Security and a second reputable tool like Malwarebytes, removing anything they find. Safe Mode prevents much malware from running, making it easier to remove. Also review installed programs and browser extensions, removing anything unfamiliar.

Be aware that some compromises are stubborn and survive a basic scan, hiding deep in the system. If the signs persist after cleaning, or if the computer handles sensitive financial or business data, it is worth having a professional verify the machine is genuinely clean rather than just quiet.

Step 4: Check what they may have accessed

Once secured, think about what the attacker could have reached: saved passwords in your browser, financial details, personal documents, and accounts you were logged into. Review recent account activity for anything you did not do, and keep an eye on your bank statements. Where saved passwords may have been exposed, change those too.

It is also worth checking your email account rules and settings, as attackers sometimes set up hidden forwarding to keep reading your mail. Removing any rules you did not create, and reviewing connected apps and devices on your key accounts, closes doors a compromise may have left open.

When to get professional help

If you cannot remove the problem, the signs keep returning, you have lost access to important accounts, or sensitive business or financial data is involved, get professional help. A compromise that is not fully cleared can keep causing harm, and verifying a system is truly clean takes experience and the right tools.

We help people across Western Sydney recover from compromised computers and accounts — removing malware, verifying the system is clean, securing accounts, and locking things down so it does not happen again. Acting quickly limits the damage, so it is worth getting help sooner rather than later if you are unsure.

Quick checklist

• Know the signs: pop-ups, redirects, unknown programs, odd logins
• Disconnect the computer from the internet
• Change key passwords from a clean, trusted device
• Enable two-factor authentication everywhere
• Scan in Safe Mode and verify the system is truly clean

Frequently asked questions