What Are Infostealers?
Infostealer malware, also called information stealers, is a class of malicious software built to harvest sensitive data from infected systems. Ransomware makes noise on purpose. Infostealers do the opposite: they run quietly, copy credentials, cookies, cryptocurrency wallets and other valuable files, and exfiltrate them before the victim notices anything is wrong.
Why the Threat Has Grown
Over the past two years, infostealer volume has jumped. Families like RedLine, Raccoon, Vidar and the newer Lumma stealer are now default tooling for a large slice of the criminal market. In our research at Revealer.US, infostealer logs make up a large share of the compromised credentials that surface in underground markets.
Why Infostealers Are So Effective
- Low barrier to entry: Malware-as-a-Service (MaaS) models let novice attackers deploy sophisticated stealers without writing code
- Stealth operations: Modern infostealers are built to evade detection and leave few obvious traces
- Broad data theft: A single infection can yield browser passwords, session cookies, autofill data and more
- Rapid monetization: Stolen data can be sold or used within hours of collection
Common Distribution Methods
Infostealers show up through a short list of channels:
- Cracked software: Fake downloads of popular applications bundled with malware
- Phishing emails: Malicious attachments disguised as invoices, shipping notices or business documents
- Malvertising: Compromised ads leading to drive-by downloads
- Social engineering: Fake job offers, gaming cheats and cryptocurrency tools
What Data Do They Steal?
Modern infostealers collect widely rather than selectively.
Browser Data
- Saved passwords from Chrome, Firefox, Edge and other browsers
- Session cookies that enable account takeover without knowing the password
- Autofill information including addresses and payment cards
- Browsing history and bookmarks
System Information
- Hardware IDs and system specifications
- Installed software list
- Network configuration
- Screenshots of the desktop
Cryptocurrency
- Wallet files and private keys
- Browser extension data for hot wallets
- Exchange session tokens
Messaging and Social
- Discord tokens and session data
- Telegram session files
- Gaming platform credentials
The output of all this collection is a stealer log: a per-device archive of everything the malware pulled. If you have never looked at one, our breakdown of what stealer logs contain walks through the structure record by record.
Enterprise Impact
For an organization, one employee infection can lead to:
- Credential compromise: VPN, email and internal application access
- Session hijacking: Attackers bypass MFA using stolen cookies
- Data breaches: Access to sensitive corporate information
- Supply chain attacks: Compromised development environments
The last one is the one teams underweight. A developer's machine holds cloud keys, signing credentials and repository tokens. One infection there is almost never one account.
Detection and Prevention
For Individuals
- Use a reputable password manager instead of browser password storage
- Enable MFA everywhere, while understanding that cookie theft can bypass it
- Avoid cracked software and unsigned installers
- Keep endpoint protection updated and run regular scans
- Check whether your address already appears in known breach and stealer data with an email lookup
For Organizations
- Deploy endpoint detection and response (EDR) coverage on every managed device
- Monitor for credential exposure across known breach datasets and stealer sources
- Enforce conditional access policies that flag anomalous sessions
- Run security awareness training on the specific lures above, not generic phishing advice
How Revealer.US Helps
Revealer.US is an OSINT and people-search platform. One search by email, username, phone number, name or address checks 800+ platforms, public records and known breach datasets, so a security team can see which of its identifiers already appear in circulating data.
For credential-specific work, the data breach lookup tool checks a single identifier against known breach datasets, and the stealer logs view focuses on device-level exposures from infostealer campaigns.
A note on scope: Revealer.US is not a consumer reporting agency, and results must not be used for employment, tenant or credit decisions.
Conclusion
Infostealers made account takeover cheap. They are quiet, they take a lot, and anyone can rent them. That combination is why they keep working against both home users and enterprises. If you do not know how they operate, the rest of the defense is guesswork.
Assume credentials will be exposed at some point. The variable you control is how quickly you find out and how fast you can rotate.
Frequently asked questions
What is the difference between an infostealer and ransomware? Ransomware announces itself by encrypting files and demanding payment. An infostealer stays silent, copies credentials and session data, and leaves. Many victims never see an alert at all.
Can MFA stop an infostealer? Not on its own. MFA blocks an attacker who only has a password, but infostealers also steal session cookies, which represent an already-authenticated session. Conditional access rules and short session lifetimes close more of that gap than MFA alone.
How do I know if my credentials are in a stealer log? Search your email address or username against known breach and stealer datasets. Our data breach lookup and stealer logs tools do this from a single identifier.
What should I do first if I find my credentials exposed? Rotate the password on the affected account and every account that reused it, then revoke active sessions so stolen cookies stop working. Review recent sign-in logs before you consider the incident closed.
Does removing the malware fix the problem? No. Cleaning the device stops further collection, but everything already exfiltrated is still in circulation. Treat every credential and session token that existed on that machine as compromised.
Are personal devices a real enterprise risk? Yes. Employees frequently save work credentials in personal browsers, and stealer logs do not distinguish between a home laptop and a managed one.
Want to check whether your organization appears in infostealer campaigns? Start a free trial of Revealer.US, or see the pricing tiers from free through self-serve at $12.99/mo.