Most people imagine hacking as a dramatic event — a skull appears on the screen, files disappear, alarms go off. The reality is the opposite. The most effective hacks are silent. Attackers want to stay inside your computer as long as possible: reading your emails, logging your passwords, watching your banking activity, and using your device as a relay point for further attacks. By the time most people realise they have been hacked, the attacker has been inside for weeks or months.
This guide covers the ten clearest warning signs that your PC has been compromised, what each one means, and exactly what to do. It also covers the two categories of tools — antivirus software and a VPN — that prevent the most common attack methods before they happen.
The 10 warning signs your PC has been hacked
1. Your passwords stop working
If you try to log into your email, social media, or bank account and your password is suddenly wrong — and you know you did not change it — this is one of the most serious signs of a hack. It means an attacker has gained access to that account and changed the credentials to lock you out. This is the final step of an account takeover.
What happened: either your password was captured by malware on your computer, obtained through a data breach of a service you use, or guessed through a credential stuffing attack (trying passwords stolen from other breached services). The attacker changed the password once they had access to prevent you from recovering the account quickly.
What to do immediately: Use the account's "Forgot password" or recovery option to regain access. Do this from a different device if possible — if your computer has a keylogger, typing a new password on it immediately compromises the new one. Once you have access, enable two-factor authentication and review recent account activity for anything you did not do.
2. Friends report strange messages from your accounts
If people in your contacts tell you they received unusual emails, social media messages, or texts from you — asking for money, containing strange links, or saying things out of character — your account has almost certainly been compromised. This is one of the most reliable indicators because it comes from an external source who has no reason to lie.
Attackers use compromised accounts for two purposes: to send phishing links to your contacts (who trust messages from you), and to commit fraud by asking contacts for emergency money transfers. Both are common and both require urgency — they want to act before you notice.
What to do: Immediately change the password for the affected account and enable two-factor authentication. Notify your contacts not to click any links in recent messages from you. Check whether any other accounts use the same password — change those too.
3. Unfamiliar programs appear on your computer
Software you did not install appearing on your computer is a direct sign of compromise. Check your installed programs list — in Windows, go to Settings → Apps. On a Mac, look in Applications in Finder. Sort by installation date and look at what was added recently.
Common things attackers install: remote access tools (allowing them to control your computer), keyloggers (recording everything you type), cryptocurrency miners (using your processor to mine cryptocurrency for them), and additional malware droppers that install further payloads.
Also check your startup programs. Press Ctrl + Shift + Esc, click the Startup tab, and look for anything unfamiliar. Malware almost always adds itself to startup so it persists across reboots.
4. Your antivirus has been disabled
One of the first actions sophisticated malware takes after infecting a computer is to disable or modify the existing security software. If Windows Defender has turned itself off, if your antivirus reports an error it never reported before, or if the antivirus interface simply will not open, something may have disabled it.
This is particularly telling because antivirus software does not disable itself. A genuine update might cause a temporary issue, but persistent disabling — especially if the software reactivated by going to its settings — indicates interference.
What to do: Try to re-enable your antivirus. If it will not stay enabled, this is strong evidence of active malware. Boot into Safe Mode and run a scan from there, or use a second scanner like Malwarebytes on a USB drive. Consider switching to an antivirus with self-protection features — Bitdefender Total Security and ESET HOME Security Premium both include tamper protection that makes them significantly harder for malware to disable.
5. Your computer's cursor moves on its own
If you see your mouse cursor moving without you touching it, windows opening or closing, text being typed, or your computer performing actions autonomously — you are almost certainly watching a live remote access session. An attacker is controlling your computer in real time.
This is a Remote Access Trojan (RAT) — malware that gives an attacker full remote control of your computer, including your screen, keyboard, files, and camera. RATs are used to steal files, capture banking credentials during live sessions, and conduct transactions using your accounts while logged in as you.
What to do immediately: Disconnect from the internet right now — pull the network cable or disable Wi-Fi. This ends the attacker's session. Do not reconnect until you have scanned the computer with an antivirus from Safe Mode and identified and removed the RAT. Change all passwords from a different device before reconnecting.
6. Your internet connection is unusually slow
A suddenly slow internet connection that cannot be explained by your internet provider's service status can indicate malware. Several types of malware consume bandwidth: cryptocurrency miners communicate with mining pools, botnets receive and execute commands, spyware uploads captured data, and some malware sends spam from your connection.
Check your network activity. In Windows, open Task Manager → Performance → Open Resource Monitor → Network tab. Look at which processes are sending or receiving data. Any process consuming significant bandwidth that you do not recognise warrants investigation. On a Mac, use Activity Monitor → Network.
Compare your router's traffic statistics against your normal usage. Most routers show connected devices and their data usage in the admin interface (usually at 192.168.1.1 or 192.168.0.1). Unexpected devices connected to your Wi-Fi, or dramatically higher data usage than normal, both deserve investigation.
7. Your webcam or microphone activates unexpectedly
The indicator light next to your webcam turning on when you are not using any application that requires the camera is a serious warning sign. Legitimate software can activate this light, but no legitimate software does so without your knowledge. If the camera light activates while your computer is idle, or during activities that have no reason to use the camera, treat this as a potential RAT infection.
In Windows 11, you can see which apps have recently accessed your camera and microphone by going to Settings → Privacy & Security → Camera/Microphone. Look for any application you do not recognise or that has accessed these devices at unexpected times.
Some advanced RATs can activate the camera while suppressing the indicator light — a technique originally developed for intelligence operations and now available in criminal toolkits. Bitdefender's Webcam Protection and Kaspersky Premium both block unauthorised camera access at the driver level, meaning they can prevent this even when the operating system cannot detect it.
8. Files have been modified, moved, or deleted without your action
If you notice files in unfamiliar locations, documents with modification dates from times you were not using the computer, or files that have been deleted that you know you did not delete, someone or something else has been active on your file system.
This can be an attacker actively exploring your files for valuable data, automatic malware behaviour (some malware searches specifically for financial documents, cryptocurrency wallets, and password files), or preparation for a ransomware attack — attackers sometimes map a victim's files before deploying ransomware to understand how much leverage they have.
Check your recently modified files. In Windows Explorer, go to This PC and in the search bar type datemodified:this week to see everything modified in the last seven days. Review the results for anything unexpected.
9. Unusual activity in your financial or email accounts
Login notifications from unfamiliar locations, transactions you did not make, emails sent from your account that are not in your sent folder, or changes to your account settings — these all indicate that someone else has access to your accounts. This may or may not involve malware on your computer directly; it could also be the result of a phishing attack or a data breach at a service you use.
Enable login notifications for all important accounts. Every major email provider, bank, and social media platform offers alerts for logins from new devices or locations. These cost nothing to set up and provide immediate notification of account compromise, regardless of whether it came from malware on your device or an external attack.
10. Your security software reports a threat it cannot remove
If your antivirus detects something, quarantines it, but the same threat keeps reappearing — or if it reports a threat but says it cannot remove it — this indicates a persistent or deeply embedded infection. Rootkits, bootkits, and some advanced trojans install themselves at a level below the operating system where standard removal tools cannot reach them.
This requires a more aggressive response: booting from a rescue disk that scans before Windows loads, or in extreme cases, a full Windows reinstallation. ESET HOME Security Premium includes ESET SysRescue, a bootable rescue tool specifically designed for this situation. Bitdefender Rescue Environment does the same.
How to confirm whether you have actually been hacked
Warning signs are not proof. Before assuming the worst, confirm whether you have an actual security incident or an innocent explanation. Here is a systematic approach:
Check Have I Been Pwned
Go to haveibeenpwned.com and enter your email address. This free service, maintained by security researcher Troy Hunt, checks your email against a database of 13 billion accounts stolen in known data breaches. If your email appears, your password for that service was exposed — and if you reused that password elsewhere, those accounts are at risk.
Run a full antivirus scan
Run a full system scan — not a quick scan — with a trusted antivirus. If you are concerned your existing antivirus has been compromised, download a second scanner to a USB drive from a clean computer and run it from Safe Mode. Malwarebytes and the free version of Bitdefender Virus Scanner are both effective second-opinion tools.
Check active network connections
Open Command Prompt as Administrator and type netstat -ano. This shows all active network connections and which process ID (PID) is making them. Look for connections to unfamiliar IP addresses, particularly connections in the ESTABLISHED state to addresses you do not recognise. You can look up any IP address at whatismyipaddress.com/ip-lookup to see what organisation it belongs to.
Review Windows Event Logs
Press Win + R, type eventvwr and press Enter. In Event Viewer, go to Windows Logs → Security. Look for Event ID 4624 (successful login) at times you were not using your computer, or Event ID 4625 (failed login) in large numbers — which could indicate a brute-force attempt. Event ID 4648 indicates a login using explicit credentials, which can indicate malware using stored credentials.
What to do if you have been hacked
- Disconnect from the internet immediately. This stops data leaving your computer and ends any live remote access session.
- Do not turn the computer off yet. Some forensic information about what happened exists only in memory and is lost on shutdown. If you want to investigate what happened, document everything you can see first.
- Change passwords from a different device. Use your phone, tablet, or another computer. Start with email (everything else can be recovered through email), then banking, then other important accounts.
- Enable two-factor authentication on everything important. Email, banking, social media, cloud storage. Do this from the clean device before reconnecting your compromised PC.
- Scan your computer in Safe Mode. Boot into Safe Mode (hold Shift and click Restart in Windows) and run a full antivirus scan. Safe Mode prevents most malware from running during the scan.
- Contact your bank. If there is any chance your banking credentials were captured, call your bank directly (using the number on the back of your card, not a number from an email) and inform them. They can monitor your account for suspicious transactions and temporarily block international transfers.
- Consider a clean reinstall. If you are not confident the malware has been fully removed, reinstalling Windows from scratch is the only guaranteed way to start clean. Back up your personal files first, then reinstall.
- Report it. In the UK, report to Action Fraud (actionfraud.police.uk). In the US, report to the FBI's IC3 (ic3.gov). In Europe, report to your national CERT. Reporting contributes to intelligence that helps authorities pursue the attackers.
Best antivirus to prevent hacking in 2026
Antivirus software is your first and most important layer of defence against hacking. The attacks that lead to most PC compromises — malware delivered through email attachments, malicious downloads, exploit-laden websites — are stopped by antivirus before they can establish a foothold. Here are the two we recommend most strongly for hack prevention specifically:
Best VPN to prevent hacking on public networks
A VPN (Virtual Private Network) does not prevent every type of hacking — it does not stop malware you download, and it does not protect against phishing. What it does prevent is a specific and common attack: the interception of your network traffic on public Wi-Fi.
How hackers exploit public Wi-Fi
When you connect to a coffee shop, hotel, airport, or any public Wi-Fi network, your traffic travels over a shared network that anyone on the same network can potentially monitor. An attacker on the same network can conduct a man-in-the-middle attack — positioning themselves between your device and the router, allowing them to see your traffic, intercept login sessions, and inject malicious content into pages you visit. This requires only basic equipment and freely available tools, and it happens in public places regularly.
A VPN encrypts all your traffic between your device and the VPN server. Even if an attacker is intercepting your connection, they see only encrypted data they cannot read. The attack becomes useless.
NordVPN — Best Overall VPN for Security
Score: 9.1/10 — BEST OVERALL
NordVPN is the VPN we recommend most for security-focused users. The independently audited no-logs policy (verified by PwC and Deloitte) means that even if NordVPN's servers were seized by law enforcement or hackers, there is no record of your activity to find. The Threat Protection Pro feature blocks malware domains, trackers, and known phishing sites at the DNS level — meaning dangerous sites are blocked before they even load, independent of whether your antivirus catches them.
Meshnet allows you to create an encrypted private network between your own devices, useful for securely accessing your home computer remotely without exposing it to the internet. The Double VPN feature routes traffic through two servers for an additional layer of encryption — relevant for high-risk environments. NordVPN operates 6,700+ servers in 111 countries, with NordLynx protocol delivering speeds that average only 11% below your base connection — fast enough for everything.
Security-specific features: Audited no-logs policy, Threat Protection Pro (malware + phishing blocking), Double VPN, Onion over VPN, Kill Switch, DNS leak protection
Best for: Users who want the most security-focused VPN with the strongest verified privacy credentials.
Surfshark — Best Value VPN with Strong Security
Score: 8.9/10 — BEST VALUE
Surfshark's Nexus technology is worth understanding for security purposes. Rather than routing your traffic through a single VPN server, Nexus routes it through the entire Surfshark network — making traffic analysis significantly more difficult because there is no single point that sees both your origin and your destination. CleanWeb blocks ads, trackers, and malware domains before they load. Alternative ID generates disposable email addresses and identities for signing up to services — keeping your real identity out of databases that get breached and sold.
Surfshark covers unlimited devices on one subscription, making it practical to protect every device in your household simultaneously. The no-logs policy was independently audited by Cure53. At a significantly lower price than NordVPN, it offers genuinely strong security features for users who want protection without premium pricing.
Security-specific features: Nexus routing, CleanWeb (malware + ad blocking), Alternative ID, Camouflage Mode (hides VPN use), MultiHop (Double VPN), Audited no-logs
Best for: Users protecting multiple devices, households, and anyone who wants strong security at the best value per device.
When a VPN does and does not protect you
- Traffic interception on public Wi-Fi
- Man-in-the-middle attacks on shared networks
- Your internet provider monitoring your activity
- IP-based tracking and profiling
- DNS snooping by your network provider
- Malware you download (use antivirus for this)
- Phishing websites you visit willingly
- Data breaches at services you use
- Keyloggers already on your device
- Social engineering attacks
The combination of a strong antivirus and a VPN covers the two most common real-world attack vectors: malware delivery and network interception. Together, they address the majority of ways ordinary users get hacked.
How to make your PC nearly impossible to hack
Most successful hacks exploit one of a small number of predictable weaknesses. Eliminating those weaknesses makes you a significantly harder target — most attackers will move to an easier one.
The highest-impact security habits
- Use unique passwords for every account. The single biggest source of account compromise is credential reuse. When a service is breached — and services are breached constantly — attackers take the stolen email and password combinations and try them on every major website. If your LinkedIn password is also your email password, a LinkedIn breach compromises your email. Use a password manager (included with every antivirus we reviewed) to generate and store unique passwords for every account.
- Enable two-factor authentication (2FA) everywhere. Even if an attacker has your correct password, 2FA prevents them from logging in without the second factor — a code from your phone, a hardware key, or a biometric. Enable it on your email first (email is the recovery method for every other account), then banking, then everything else. Use an authenticator app (Google Authenticator, Authy) rather than SMS where possible — SMS 2FA can be bypassed through SIM-swapping attacks.
- Keep everything updated. The majority of successful hack attempts exploit known vulnerabilities in software that already has a patch available. Attackers know that most users do not update promptly, so they exploit the window between a patch being released and users installing it. Enable automatic updates for Windows, your browser, and all applications. Avira Prime's Software Updater patches third-party applications automatically — addressing the apps that Windows Update does not cover.
- Do not reuse passwords, and do not store them in your browser. Browser-stored passwords are one of the first things malware and attackers look for. Many information-stealing malware types — Redline Stealer, Raccoon Stealer, Vidar — specifically target browser credential stores. A dedicated password manager encrypts your passwords with a master key; browser storage typically does not.
- Use a VPN on public networks. Always. Any network you do not control — coffee shops, airports, hotels, co-working spaces — is a potential interception point. Make it a habit to connect your VPN before connecting to any public Wi-Fi. NordVPN and Surfshark both have auto-connect features that activate the VPN whenever you join a new network, removing the need to remember.
- Be sceptical of everything unexpected. Phishing emails, smishing texts, vishing phone calls, and fake technical support pop-ups all rely on creating urgency that overrides your caution. Your bank will not email you demanding immediate action. Microsoft will not call you about a virus on your computer. The tax authority will not demand payment in gift cards. Slow down, verify through official channels, and never provide credentials or payment in response to an unsolicited contact.
- Audit your connected apps regularly. Go to your Google, Microsoft, Facebook, and Apple account security settings and review which third-party apps have access to your account. Remove anything you do not recognise or no longer use. Each connected app is a potential entry point — if the app is compromised, attackers gain whatever access you granted it.
- Cover your webcam when not in use. A physical webcam cover costs less than a coffee and completely eliminates the risk of remote camera access, regardless of what software is or is not running. This is not paranoia — it is a simple, cheap, effective countermeasure for a real attack vector.
Security checklist: your 10-minute setup
- ☐ Install a trusted antivirus — Bitdefender Total Security or ESET HOME Security Premium
- ☐ Install a VPN — NordVPN or Surfshark
- ☐ Enable two-factor authentication on email and banking
- ☐ Set up a password manager and change reused passwords
- ☐ Enable automatic updates on Windows and all apps
- ☐ Check haveibeenpwned.com for your email address
- ☐ Review connected apps in your Google and Microsoft accounts
- ☐ Enable login notifications on important accounts