Cyber criminals don’t always need to break into a system using brute force or sophisticated exploits. Sometimes, all it takes is a single careless click to hand over everything they need.
Once seen as a niche threat, infostealers are now a common feature in cyber attacks against both individuals and businesses. In this post, we break down what infostealers are, how they work, and how you can reduce your risk of falling victim.
An infostealer is a type of malware specifically designed to collect and extract information from an infected device. This typically includes usernames, passwords, browser cookies, credit card details, and other sensitive files or credentials.
The data is often sent back to a remote command-and-control (C2) server controlled by the attacker. From there, it may be used for further attacks, sold on the dark web, or used to impersonate the victim and access corporate systems.
What sets infostealers apart is their speed and silence. Many can complete their task in under a minute, often without leaving any visible trace on the machine. By the time the victim notices something is wrong, the damage is already done.
Infostealers typically enter systems in the same ways most malware does via phishing emails, malicious links, cracked software downloads, or poisoned adverts on legitimate websites. Once installed, the malware runs quietly in the background, extracting information in several ways:
In more sophisticated campaigns, the malware can even detect if it's running in a sandboxed or monitored environment and remain dormant to avoid triggering alarms.
Infostealers don’t just pose a risk to individual users. When deployed on corporate networks, they can result in:
Infostealers are frequently part of broader toolkits, so they are often just the first step in a longer chain of attack that might end in ransomware or extortion.
The numbers are hard to ignore. Infostealers were the cause of nearly a quarter (24%) of all cyber incidents in 2024 and it’s predicted that this will continue to grow.1
Once extracted, the stolen data is usually sent to a central server or traded on dark web marketplaces. Some attackers use automated bots on platforms like Telegram to sell credentials by brand or domain. A buyer can request all logins for a specific company, pay a small fee, and receive full access within minutes.
This data often fuels further attacks, such as:
Interestingly, not all data stolen by infostealers is useful. Many credentials are outdated, mis-typed, or belong to previously compromised systems. Sometimes attackers themselves are victims, and malware logs can contain data from other criminals testing stolen passwords on infected machines.
This doesn’t reduce the threat it only reinforces the scale of the problem. Stolen data is messy, but even one valid login can be enough to breach a company.
There is no single fix for infostealers, but the following steps significantly reduce risk:
Infostealers aren't new, but the scale and sophistication of today’s attacks are a different beast. The days of opportunistic, clumsy malware are long gone. What we’re seeing now is highly automated, often rented infrastructure, capable of harvesting credentials in seconds and selling them just as fast.
For businesses, this means the fallout isn’t limited to a single compromised account it’s access to systems, client data, financials, and potentially the entire supply chain. One infection can open the door to a much larger breach.
If you want to discuss this further, please get in touch.