Infostealer Logs Explained: How Stolen Credentials Arise and What You Can Do
Infostealers are malicious programs that read stored credentials, browser data and session cookies from an infected device. The collected data is bundled into “logs” and often traded in forums, messaging channels or marketplaces. They matter to companies because the logs can contain access to company services.
What an infostealer typically steals
- usernames and passwords saved in the browser
- session cookies and tokens of logged-in services
- autofill data, browsing history and device information
- depending on the malware, further files and cryptocurrency wallets
Why session cookies are a particular risk
If a valid session cookie is stolen, an attacker may be able to impersonate the user without logging in again. Depending on the service and its configuration this can bypass protections such as an additional confirmation step. That is why changing a password alone is not always enough.
How companies reduce the risk
- Keep endpoints protected and updated; don't install unknown software.
- Don't store passwords in the browser; use a password manager with central management.
- Enforce multi-factor authentication, ideally phishing-resistant, for company services.
- End sessions centrally when in doubt and revoke tokens.
- Clean affected devices before changing passwords – otherwise the new credentials are captured again.
How to find indications of affected access
A data breach check can show whether publicly known indicators exist for your domain. For ongoing observation, dark web monitoring is suitable. Neither replaces securing your endpoints.
Frequently asked questions
Is a new password enough after an infostealer finding?
Not always. Clean the device and revoke sessions first, then change passwords and review MFA.
Are only Windows machines affected?
No. Infostealers exist for several operating systems; what matters is protection and behaviour on the devices.
Is your domain affected? The free BreachFinder check shows known data breaches for your domain.
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Updated: 2026-09-26. General information, not legal advice.