Data breaches often go unnoticed by the people affected for weeks or months, which gives attackers a long head start. Knowing the warning signs and having a response plan ready shortens that window considerably.

Common warning signs

• An email notification from a service you use, confirming a breach
• Login attempts or password reset emails you didn't initiate
• Unfamiliar activity on a linked financial account

What to do immediately

1. Change the password on the affected account

Generate a new, unique password with a password generator rather than a slight variation of the old one.

2. Check for password reuse elsewhere

If you used the same password anywhere else, change it there too, since attackers actively try leaked credentials across other popular services.

3. Enable two-factor authentication

Adding a second factor closes the door even if the password itself remains compromised somewhere an attacker hasn't tried yet.