What Is a Stealer Log Breach and Why Is It More Serious?
Normal breaches start at a company. Stealer logs start on a personal device, which changes what you need to do.
By Siddharth ShankarUpdated October 11, 2026A stealer log is data captured by malware running on an infected device, usually the website, email address and password typed into it. Unlike a company breach, the source is your own device, so changing passwords from the same infected machine may not help. Clean or replace the device first, then change passwords and enable multi-factor authentication.
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If a breach-checking service shows your email address in something called a stealer log, the usual advice to change your password at the affected website is not enough. Stealer logs behave differently from the breaches most people picture.
What a stealer log is
Have I Been Pwned (HIBP) explains stealer logs this way: malware running on infected machines collects emails, passwords and the sites they were entered into. Troy Hunt, who runs HIBP, describes infostealers as malware that captures credentials entered into websites on input. Each entry is typically a website address, an email address and a password.
So a stealer log is not a record of one company's database. It is a record of what was typed on infected devices, gathered across many sites at once.
How it differs from a normal breach
In a normal breach, a company's systems are compromised, and everyone in its database is exposed. In a stealer log, the compromise happened on an individual device, and the data reflects that user's activity on any site.
- Source: the victim's own computer, not the website.
- Scope: every site the person logged into, not one company.
- Freshness: because the data is captured as people type, logs can contain credentials that still work. Troy Hunt calls stealer logs a firehose of data that is constantly spewing personal info.
That combination is why it is considered more serious. Credentials in a stealer log may be current, and they may be for several of your accounts at once.
What HIBP stores and shows
HIBP stores the email address and the domain names of the sites that appear in a log, not the passwords next to your personal data. You can find your address through Notify Me and through a dedicated stealer-log lookup, and the site domains are visible in the stealer log section of a personal dashboard. Passwords from these collections can be checked through Pwned Passwords.
HIBP has named some stealer-log collections by date, such as "Stealer Logs, Jan 2025". It also marks them with a flag in its data so tools can distinguish them from website breaches.
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What to do if you appear in a stealer log
1Treat the device as suspect
The data came from a device that ran malware. Run a reputable security scan, remove anything suspicious and consider a clean reinstall if you cannot be sure. We say this because a password changed on a still-infected machine can be captured again.
2Change passwords from a clean device
Start with email, then banking, then any site shown in your log. Do not reuse old passwords.
3Turn on multi-factor authentication or passkeys
These reduce what a stolen password alone can do. The NCSC recommends passkeys over passwords wherever they are available.
4Review account activity
Look at recent logins, forwarding rules, connected apps and recovery details on your email and key accounts.
5Watch for fraud
Check bank and card statements, and place a credit freeze if financial details may have been exposed. See the credit freeze guide.
Why password changes alone may not be enough
If the malware is still on your device, it can capture the new password as soon as you type it. That is the main practical difference from a website breach, where changing the password at the affected site closes the door.
How malware gets onto devices
We have not verified the delivery methods behind specific collections, so we will not claim them. In general, malware reaches devices through the same routes as other threats, such as downloads from untrusted sources and phishing links. Staying away from pirated software, keeping devices updated and reading how to tell if a data breach notice is real or phishing help.
How stealer logs relate to credential stuffing
Stolen logins feed the same pipeline as breached passwords: attackers test them on other sites. Read credential stuffing explained for the defences.
Sources
- Have I Been Pwned: FAQs (what stealer logs are; searchable via Notify Me and an API)
- Troy Hunt: Inside the Synthient threat data (infostealers capture credentials on input; 'firehose')
- Have I Been Pwned: API v3 (stealer log lookups and IsStealerLog flag)
Frequently asked questions
Does being in a stealer log mean my device is infected now?
Not necessarily. The infection may have been removed since, or the device may be old. Treat the device as suspect until you have checked it.
Are stealer logs and normal breaches listed together?
HIBP lists them as breach entries with a specific flag, so you will see them alongside other entries in your results.
Do stealer logs include my passwords?
The original collections can, which is why HIBP lets you check passwords in Pwned Passwords. HIBP does not store passwords alongside personal data.
What if I use a password manager?
It helps because passwords are unique per site, but malware that runs on the device may still capture what is typed or filled. Clean the device first.
Is a stealer log the same as being hacked?
Your accounts are not necessarily compromised, but the credentials in a log may work. Change them and enable multi-factor authentication.
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