Infostealers: How to Check If Malware Has Stolen Your Passwords

What is an infostealer?

An infostealer is malware built to grab credentials fast and quietly. It copies the passwords saved in your browser, active session cookies, autofill entries, and often cryptocurrency wallet files, packages them into a structured stealer log, sends it to the attacker, and exits. Unlike a breach of one company, it takes everything on the machine at once.

People usually catch it from a fake download, a cracked app, a malicious browser extension, or an attachment in a convincing email. There is often no crash and no warning. The first sign is often an account being accessed from somewhere you have never been.

How is a stealer log different from a normal data breach?

A data breach exposes one company's users. A stealer log exposes one person's entire saved-login vault across every site they use, along with the live session cookies that can let an attacker skip the password entirely. That is why security researchers now treat fresh stealer logs as more dangerous than older breach dumps.

The 24 billion record collection uncovered in 2026 was weighted heavily toward fresh infostealer logs rather than static breach data, which is what made it such a live threat. If your device was infected, your exposure is not one site, it is the list of every site whose password you had saved.

How do you check if an infostealer has your passwords?

Check a breach index that includes stealer-log data, then scan the device itself. Have I Been Pwned now indexes stealer logs and, after you verify your email through its free notification service, shows you the specific websites your credentials were captured against.

1. 1.Search your email on Have I Been Pwned ↗. If it appears in stealer-log data, verify your address through its notification service to see the exact websites your credentials were logged against.
2. 2.Run a full scan with a trusted anti-malware tool to find and remove the infostealer itself, because a breach check tells you that you leaked, not whether the malware is still running.
3. 3.Check every device that shares those saved logins, not just the one you suspect.
4. 4.Treat any password that appears in a log as burned, on that site and anywhere you reused it.

Why changing your password is not enough

Because infostealers also grab session cookies. A stolen session cookie can let an attacker into your account without the password and, in many cases, without tripping two-factor authentication, because the site already treated that session as logged in. Changing the password does not always kill an existing session.

The fix is to sign out of all devices, which forces the site to issue new sessions and makes the stolen cookie useless. Do that alongside the password reset, not instead of it.

What to do if you are in a stealer log

1. 1.Remove the malware first: run a full scan on every affected device and clear out suspicious browser extensions before you change anything, or the new passwords leak too.
2. 2.Change passwords to unique ones, a different password per site, starting with email, banking, and anything holding money or identity.
3. 3.Sign out of all active sessions on your important accounts to invalidate stolen cookies.
4. 4.Turn on two-factor authentication, and prefer an app or a passkey over SMS.
5. 5.Watch your email, bank, and shopping accounts for logins and changes you did not make.

A stealer log is the clearest example of why a single breach check is not enough: the same email ties together accounts, reused passwords, and old exposure you have long forgotten. Clearfront scans that whole picture in one sweep on your own machine, and an AI security analyst spells out what is exposed and where to start. Install Clearfront free and run it on your own email, or get the free removal guide if you would rather work from a checklist.