What to do when an infostealer is active

If you suspect an infostealer is active in your environment, immediate response is critical. These infections often go undetected by traditional tools, while silently leaking credentials, session tokens, and business data. Attackers can act within minutes.

Based on real-world incident patterns, these are the steps security teams take to contain an infection, investigate exposure and regain control.

Here’s the core framework:

1. Revoke access immediately, Disable affected accounts, force logouts, and invalidate session tokens across internal systems and cloud platforms.

2. Investigate potential misuse, Review logs for suspicious logins, lateral movement, or data access.

3. Clean the infected device, Scan with EDR tools or reimage the machine to eliminate persistence.

4. Reset credentials, Treat all passwords and session tokens as compromised.

5. Strengthen long-term defences, Improve visibility, reduce reliance on unmanaged devices, and close detection gaps.