How to tell if your computer has been hacked: 7 telltale signs

Is your computer acting strangely? It may have been compromised by hackers. Here are the 7 unmistakable signs and the actions to take immediately to secure a hacked computer.

Symptoms of a hacked computer

Sudden, unexplained slowdown: if your PC suddenly becomes slow for no apparent reason, malicious programs may be consuming your resources in the background. Cryptominers and botnets are particularly hungry for computing power.

Intrusive pop-ups and ads appear even when you are not browsing the internet. This adware often installs itself alongside free software and turns your browsing into an advertising nightmare.

Unknown programs at startup: check your Task Manager regularly. Processes with suspicious names or high resource usage can reveal an infection.

Unauthorised changes to your home page, search engine or desktop shortcuts often signal browser hijacking.

Technical checks to carry out immediately

Analyse your network traffic using Windows Resource Monitor. Heavy network activity while you are not actively using the internet may indicate that your data is being exfiltrated.

Check your recent sign-ins on your email and social media accounts. Logins from unknown locations reveal unauthorised access to your credentials.

Monitor disk usage: storage space that shrinks rapidly can signal the installation of bulky malware or the creation of suspicious temporary files.

Emergency actions if your PC is compromised

Disconnect your computer from the internet immediately to stop data exfiltration and block the hackers’ remote commands.

Run a full antivirus scan with up-to-date software. If your usual antivirus finds nothing, get a second opinion with Malwarebytes or ESET Online Scanner.

Change all your passwords from a clean device. Prioritise your bank, email and social media accounts. A secure password manager will make this crucial task easier.

Monitor your bank accounts and credit card statements for any fraudulent transactions. Contact your bank at the slightest doubt.

Prevention to avoid future intrusions

Prevention remains the best defence: keep your system up to date, use an effective antivirus, be wary of suspicious emails and regularly back up your important data.