Infostealer malware is a category of malicious software designed to quietly collect sensitive data from an infected computer or browser. Typical targets include saved passwords, autofill data, browser cookies, cryptocurrency wallets, SSH keys, and files from common directories. Once collected, the malware packages everything into structured logs and sends them to attacker-controlled infrastructure.
Unlike ransomware that announces itself, infostealers often run silently in the background. Victims may not know they are compromised until credentials from their machine show up in criminal marketplaces or are used in follow-on attacks. For security teams, infostealer infections are one of the most reliable early warning signals for account takeover, initial access sales, and ransomware precursors.
Hudson Rock tracks millions of infostealer infections globally. Our research shows infections frequently start from cracked software, fake game cheats, and malicious browser extensions. Read how real victims describe the aftermath in our Reddit infostealer infection report, or see the top four ways attackers actually use infostealers.