What is How to Check If You've Been Hacked?
Steps to determine if your accounts, devices, or personal information have been compromised in a data breach or security incident.
If you suspect you've been hacked, here's how to check and what to do.
Check for Data Breaches
- Have I Been Pwned (haveibeenpwned.com): Enter your email to see if it appeared in known breaches
- Firefox Monitor: Mozilla's breach checking service
- Default Privacy's Password Check (/password-check): Checks if passwords have appeared in breaches
Signs Your Account Was Compromised
- Password reset emails you didn't request
- Login notifications from unfamiliar locations or devices
- Sent messages or posts you didn't create
- Account settings changed (email, phone, recovery options)
- Missing emails (attacker set up forwarding rules)
Signs Your Device Was Compromised
- Unusual battery drain or overheating
- Unexpected data usage
- Apps you didn't install
- Device running slowly for no reason
- Webcam/microphone indicator activating unexpectedly
Immediate Steps
- Change passwords on affected accounts (use a password manager)
- Enable MFA everywhere (hardware key > TOTP > SMS)
- Check email forwarding rules — attackers often set up auto-forwarding
- Review connected apps and revoke unauthorized access
- Scan devices for malware
- Check financial accounts for unauthorized transactions
- Freeze your credit if personal information was exposed
Related Terms
Credential Stuffing
An automated attack that uses stolen username/password pairs from one breach to try logging into other services, exploiting password reuse.
Data Breach
A security incident where protected, sensitive, or confidential data is accessed, stolen, or exposed by unauthorized individuals. Data breaches can result from hacking, insider threats, lost devices, or misconfigured systems.
Identity Theft
The fraudulent use of someone's personal information — such as Social Security number, credit card details, or login credentials — to commit crimes or financial fraud.
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