An infostealer, short for information stealer, is a type of malware built to quietly harvest sensitive data from an infected device, then send it to an attacker. It targets saved passwords, browser cookies, session tokens, autofill data, and cryptocurrency wallets, often without the victim noticing a thing.
Infostealers have quickly become the engine behind modern credential theft. In the first half of 2025 alone, they stole an estimated 1.8 billion credentials, an 800% jump over the previous six months. Those stolen logins don’t just sit on a dark web forum. They’re the opening move in account takeovers, fraud, and a fast-growing share of ransomware attacks.
Sources: Flashpoint Global Threat Intelligence Index, 2025 Midyear Edition; Verizon 2025 Data Breach Investigations Report.
An infostealer runs silently in the background of an infected device, scanning valuable data and shipping it back to the attacker. Most follow the same three-step pattern: Infect, collect, and exfiltrate.
Once it lands on a machine, the malware sweeps the usual storage spots: Browser-saved passwords, cookies and session tokens, autofill fields, email clients, messaging apps, and crypto wallet files. It bundles everything into a “log” and sends it to a command-and-control server, often within seconds. Many infostealers then delete themselves to cover their tracks.
Most are sold as malware-as-a-service (MaaS). For as little as $200 a month, a low-skilled attacker can rent a polished infostealer kit, complete with dashboards and support. That low barrier to entry is a big reason the threat has exploded. Well-known families include Lumma Stealer, RedLine, and Raccoon.
Infostealers go after anything that can be sold or reused to break into an account. The most common targets:
Infostealers reach victims through the same everyday channels people already trust. Common delivery methods include:
A single infected laptop can put an entire organization at risk. Infostealers matter because of what happens after the theft.
Stolen credentials fuel bigger attacks. According to the Verizon 2025 Data Breach Investigations Report, 54% of ransomware victims had their domains show up in infostealer logs before the attack hit. Initial access brokers buy these logs, pick out corporate VPN, RDP, and cloud logins, and sell ready-made access to ransomware crews. The gap between a stolen log and a full-blown ransomware incident can be under 48 hours.
They also slip past MFA. By stealing active session cookies, attackers can replay a logged-in session and walk into accounts without ever entering a password or a one-time code. Traditional MFA alone won’t stop them.
For a business, that means credential theft isn’t a minor IT nuisance. It’s often the first domino in data breaches, financial fraud, and ransomware that can bring operations to a halt.
Infostealers are built to stay hidden, but they leave traces. Watch for:
Because the malware often self-deletes, credential monitoring and endpoint detection usually catch infostealers faster than waiting for obvious symptoms to appear.
You can shrink both the odds of infection and the blast radius if one gets through. Strong defenses include:
Infostealers are usually the first step, not the last. The credentials they harvest often lead to ransomware or data destruction down the line. Veeam can’t stop malware from landing on an endpoint, but it makes sure a stolen password doesn’t turn into a business catastrophe.
With secure, immutable backups and fast, reliable recovery, Veeam helps you bounce back from ransomware and data loss so your business keeps running. Veeam Data Platform also adds proactive threat detection across your backups, surfacing suspicious activity early so you can respond before the damage spreads. Learn more about ransomware protection and building true data resilience with Veeam.
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