You have probably heard the advice a hundred times. Do not click suspicious links. Do not open attachments from strangers. Do not enter your password on a fake login page. Good advice. But it assumes the attacker needs your cooperation. Infostealer malware does not.
Once installed on your device, an infostealer silently extracts every saved password from your browser, every active session cookie, your credit card autofill data, your crypto wallet keys, and your two-factor authentication codes. Then it packages everything into a compressed archive called a log and uploads it to the attacker in under 60 seconds. No phishing page required. No interaction from you at all.
This is currently the fastest-growing category of cybercrime. In 2024 alone, over 100 million device logs were sold on dark web marketplaces. Your credentials are almost certainly in some of them.
What is an infostealer?
An infostealer is a category of malware with one job: extract credentials and sensitive data from a compromised device as fast as possible and send it home. Unlike ransomware, it does not encrypt your files. Unlike a keylogger, it does not wait for you to type anything. It goes directly to where browsers and applications store data on disk and reads it directly.
The most common families you will see in breach reports right now are Redline, Raccoon, Lumma, Vidar, and StealC. They are sold as subscription services on dark web forums, starting at around $100 per month, with support documentation, dashboards, and update logs just like legitimate software.
Phishing attacks require you to visit a fake page and type your password. Infostealers bypass all of that entirely. They read your already-saved passwords straight from the browser's encrypted credential store, which they can decrypt because they are running as your user on your machine. You do not have to do anything wrong after infection.
How does infection actually happen?
The most common delivery vectors right now are not email attachments. They are things that look completely legitimate.
A search for "Photoshop free download 2026" or "Warzone aimbot no ban" leads to a site with a download that looks like what you searched for. The installer bundles an infostealer alongside. This is how the majority of consumer infections happen.
Attackers post tutorial videos for popular software. The description links to a "download" that is actually a dropper. Some of these videos have hundreds of thousands of views before removal. The comments are full of bots claiming it worked fine.
Attackers create sites that rank for searches like "download VLC player" or "OBS studio free." The pages look professional. The installer is real software wrapped with a stealer payload. Google removes these regularly but new ones appear within hours.
Files shared in gaming servers, developer communities, or GitHub repositories. A shared asset pack, a Python script, an npm package. Developers are particularly targeted because their machines often have access to company infrastructure and secrets.
What gets stolen in 60 seconds
Once the stealer is running, here is the collection order. This entire process takes under a minute on a modern machine.
| Data type | Source | Risk level |
|---|---|---|
| Saved passwords | Chrome, Firefox, Edge, Safari credential stores | Critical |
| Session cookies | All browsers — bypasses 2FA entirely | Critical |
| Credit card autofill | Browser payment data | Critical |
| Crypto wallet files | MetaMask, Exodus, local wallet files | Critical |
| Email client data | Outlook, Thunderbird stored credentials | High |
| VPN credentials | NordVPN, ExpressVPN config files | High |
| Desktop screenshots | What is on your screen right now | High |
| System fingerprint | IP, OS, hardware ID, installed software | Medium |
Session cookies are the most dangerous item on that list. When an attacker has your session cookie for Gmail or your company's internal tools, they do not need your password or your 2FA code. They paste the cookie into their browser and they are already logged in as you. This is how high-profile YouTube channel takeovers happen. The creator never typed anything on a fake site.
How logs are sold and used
After exfiltration, the attacker's server receives a structured archive called a log. It contains all the data above, organized by browser and application. These logs are immediately listed for sale on marketplaces like Russian Market and various Telegram channels.
Buyers search logs by domain. They might search for "coinbase.com" and buy every log that contains a saved Coinbase password. Or they search for corporate VPN domains to target specific companies. A single log sells for between $5 and $50 depending on what is inside and how fresh it is. Logs older than 30 days drop in value sharply because passwords may have been changed.
The credentials from these logs are what end up in breach databases, credential stuffing lists, and eventually in DataLeakz's monitoring index. When you get a breach alert that says your email appeared in a stealer log, this is the process that put it there.
DataLeakz monitors dark web markets and stealer log databases in real time. If your email appears in a new log, you will know within hours.
How to protect yourself right now
Chrome, Firefox, and Edge all store passwords in a file on disk that infostealers read directly. Move to a dedicated password manager like Bitwarden or 1Password. Their data is encrypted differently and significantly harder to extract without your master password.
Easy · highest impact · do this firstGo directly to the official website of the software you need. Bookmark it. Never click a download link from a Google or YouTube search result for popular software. The risk of saving two clicks is catastrophically bad.
Easy · habit changeSession cookies only work on active sessions. Signing out regularly means stolen cookies expire quickly. Better still, move your most important accounts to passkeys where cookie-based hijacking is much harder by design.
Easy · one-time setup per accountStandard real-time antivirus sometimes misses infostealers because they run briefly and exit. An offline scan catches things that persistent AV misses. Run this now if you have ever downloaded software from a non-official source.
Easy · 15 minutesIf your credentials were stolen by an infostealer, they will eventually appear in a breach database. The earlier you know, the faster you can rotate passwords before they are used against you. Real-time monitoring is the only way to catch this without waiting for damage first.
Medium · ongoing · worth setting upAct fast. The window between infection and credential use is often less than 48 hours on fresh logs. Change your most important passwords immediately starting with email, then banking, then anything with stored payment data. Do not change them from the suspected device. Use your phone or a different machine. Then change everything from a clean device and move all accounts to passkeys where possible.
Sources
- IBM Cost of a Data Breach Report 2024 — credential theft and malware delivery statistics
- SpyCloud Annual Credential Exposure Report 2025 — infostealer log volume and combo list data
- Recorded Future Threat Intelligence 2024 — dark web marketplace pricing and stealer log analysis
- Group-IB Hi-Tech Crime Trends 2024 — Redline, Raccoon, Lumma and Vidar family breakdown
- CISA Advisory AA24-241A — infostealer malware targeting browser credentials and session tokens