What is infostealer malware? Learn the silent threat to your data

According to the KELA State of Cybercrime 2025 report, more than 4.3 million devices were infected by infostealer malware in 2024, and 3.9 billion passwords were compromised in the process. This malicious software is designed to secretly collect sensitive data from devices. The data can include passwords, credit card information, and even crypto wallet credentials.

Needless to say, infostealer malware is a threat to your data. In this post, we’ll break down what exactly infostealer malware is, how it spreads, and the kind of damage it can cause. Then we’ll go over the signs of a malware infection and what steps you can take to protect your data from infostealer malware going forward.

What is infostealer malware?

As the name suggests, infostealer malware is a type of malicious software designed to steal sensitive information from a device. Infostealer malware typically spreads through deceptive tactics such as phishing emails, fake software installers, malicious browser extensions, and compromised websites.

Unlike some more aggressive threats like ransomware, info stealer malware operates silently, often without any of the tell-tale signs of infection. Many victims don’t realise their device is compromised until it’s too late.

Once infostealer malware is installed, it quietly searches for valuable data such as:

• Saved login credentials
• Personal data
• Autofill form data
• Credit card information
• Browser cookies and session tokens
• Cryptocurrency wallet data
• Emails and chat logs
• Documents and photos
• Screenshots

The stolen data is sent back to the attacker, who may then use it for personal gain or sell it on the dark web. Depending on the information extracted, the hacker could use it to compromise other systems. For example, infostealer malware may steal login credentials or session tokens and then use this information to move laterally across a network, infiltrating other systems or accounts.

High-profile infostealers

Over the years, a number of high-profile infostealer malware strains have hit the headlines due to their effectiveness and reach. Here are some of the best-known infostealers:

• RedLine Stealer: RedLine is often sold on cybercrime forums and can steal login credentials, browser data, crypto wallet information, and more. It is frequently distributed via pirated software and phishing emails.
• Raccoon Stealer: Raccoon Stealer is sold as Malware-as-a-Service (MaaS), in which cybercriminals provide access to the software for a fee. It’s known for quickly harvesting a wide range of data from infected systems.
• Vidar: Vidar is one of the more customizable infostealers used in targeted campaigns. With it, an attacker can make away with browser data, passwords, documents, and even two-factor authentication information stored in browser extensions.
• Lumma Stealer: Lumma Stealer is a newer infostealer that receives regular updates and support, helping make it one of the more popular ones. It specializes in grabbing valuable information such as credentials and cryptocurrency data.

The risks of infostealer malware

Infostealer malware may work quietly in the background but can cause extensive damage. Once attackers have your data, they can use it in several ways. Here’s a closer look at some of the risks of infostealer malware:

Account takeover

One of the most immediate risks is account takeover. By stealing login credentials and session cookies, attackers can log into your email, banking apps, cloud storage, or social media, sometimes without triggering two-factor authentication (2FA).

That’s because some infostealers grab session tokens, letting attackers hijack your active sessions and bypass the login process. Once inside, they can lock you out, steal funds, impersonate you, or compromise linked accounts.

Identity theft and fraud

With enough personal data, such as names, addresses, IDS, or credit card info, cybercriminals can commit identity fraud. Identity thieves can open bank accounts, take out loans, or even make large purchases in your name. Victims of identity fraud can spend months recovering both personal finances and credit scores.

Sensitive data exposure

Some infostealers go beyond passwords; they collect files from your device. These can be tax documents, business files, personal photos, or copies of passports or ID cards. Armed with this sensitive data, cybercriminals can use it for blackmail or extortion. If the stolen data belongs to a company, it may even be used in corporate espionage.

Business and workplace breaches

Attackers can potentially infiltrate your workplace’s systems if you use your personal device for work or simply use the same passwords across personal and professional accounts. The risks of this are severe, ranging from data leaks to ransomware attacks. Small businesses and remote workers are often more vulnerable because they lack the protection of larger organizations.

Dark web exposure and resale

Data that’s stolen through infostealer malware doesn’t just disappear. Even if the original attacker doesn’t exploit your data directly, they may sell it on the dark web. Attackers often buy and trade access to accounts in bulk. Any information stolen from your device can be reused for months or even years in other attacks. The risks include phishing scams, social engineering attacks, and credential stuffing attempts.

Reputation damage

Beyond some financial risks, infostealer malware can cause reputational damage. If attackers gain control of your email, social media, or messaging accounts, they can impersonate you and send spam or phishing links to your contacts. They may even post inappropriate content under your name. Needless to say, this can be particularly damaging for professionals. Any loss of credibility and trust can take a great deal of time and effort to repair.

Signs of an infostealer malware infection

Infostealers are built to avoid detection, making spotting them more difficult. It’s not impossible, however, particularly if you look for the following signs:

• Unusual account activity: You may notice unusual activity across your online accounts, such as unexpected password reset emails and logins from unfamiliar locations. If you are suddenly locked out of an account or contacts receive strange messages from you, it could be a sign that your credentials have been compromised by infostealer malware.
• Browser behaviors: Watch for strange behavior within your browser, such as lost saved passwords or autofill data, unexpected account logouts, or the sudden appearance of unfamiliar browser extensions. Some info stealers are bundled with other malware that changes your browser settings, such as your homepage or search engine.
• System performance issues: Slow performance can indicate something is wrong, especially if your device is overheating, lagging, or crashing for no apparent reason. Background malware-related processes may appear in Task Manager (Windows) or Activity Monitor (macOS) under suspicious names.
• Security warnings: It’s important to take security alerts seriously. If your antivirus stops working, crashes, or flags unknown apps trying to access the internet, it could be a sign that infostealer malware is present. Many password managers warn of data breaches and reused credentials, which hint that data may already be exposed.

How to protect yourself from infostealer malware

Although infostealer malware is stealthy and poses numerous risks, you don’t need advanced skills or knowledge to protect yourself from it. Adopt the right habits and tools, and be aware of the common signs of infection.

1. Use a strong antivirus program

A reliable antivirus is your first line of defense against malware, including info-stealing malware. A quality antivirus can detect known info-stealing malware before it starts collecting your data, alerting you to any suspicious activity or unauthorized access attempts. The best antivirus programs offer real-time protection from threats and web protection features that help block dangerous downloads and phishing links.

2. Keep your software updated

Infostealers often exploit known vulnerabilities in outdated software, including our operating system, web browser, plugins, or even everyday apps. Keep all your software updated. Regular updates don’t just include new features. They patch security holes that attackers look to take advantage of. Where possible, turn on automatic updates to keep your system secure with minimal effort.

3. Avoid cracked software and shady downloads

Some infostealers are disguised as free versions of paid software or fake productivity tools. One of the fastest ways for your device to be infected is by downloading pirated or unofficial software, especially if you don’t have adequate antivirus protection in the first place. For this reason, you should stick to trusted sources and official app stores.

4. Use a reputable password manager

Although storing your passwords in your browser may be convenient, it’s also risky. Infostealers often target browser-stored credentials. Use a reputable password manager instead. A password manager securely encrypts and stores your passwords. It even helps you create strong and unique passwords for your online accounts. If one set of credentials becomes compromised, the damage is limited to one account.

5. Enable multi-factor authentication

Another line of defence against infostealer malware is multi-factor authentication. MFA adds an extra verification step to your logins by sending a one-time code to your phone, email, or authenticator app. It’s much harder for cybercriminals to gain access to an account even if they have the password, because they need to access the one-time code somehow as well.

6. Regularly monitor for data breaches

It’s important to check for data breaches regularly. Fortunately, there are many tools at your disposal. Have I Been Pwned and Firefox Monitor are two well-known options. Your password manager, antivirus, or VPN may offer a data breach tool that alerts you if your email address or credentials have been compromised. With it, you can act fast to stay ahead of attackers.

Infostealer malware FAQs