Around 90% of organizations that were breached in 2024 had their credentials leaked and available for sale on dark web marketplaces for just $10 to $15 per account. This alarming statistic can be largely attributed to infostealer malware, which is a family of specialized programs that silently harvest passwords, browser cookies, and authentication tokens from infected devices before disappearing without a trace.
For organizations of all sizes, this creates a troubling reality where a single employee clicking the wrong link or downloading compromised software can expose your entire database of digital credentials. The good news is that once you understand how infostealers operate, where stolen credentials end up, and what defenses actually work, you can implement practical protections that keep your organization out of that 90% statistic.
What Are Infostealers and How Do They Operate?
Infostealers are specialized malware designed for one purpose: extracting sensitive information from infected systems without alerting the victim (unlike ransomware, for example, which sooner or later announces its presence with encrypted files and payment demands).
The most common infostealer infection vectors include:
- Phishing emails with malicious attachments: employees open convincing messages that appear to be invoices, shipping notifications, or internal communications containing infected documents.
- Compromised software: pirated software, key generators, or “free” versions of expensive programs that bundle infostealers with the expected application are installed by employees on their work or even personal devices if they use them for work.
- Malvertising and compromised websites: Visiting legitimate sites serving infected ads or trusted websites that have been compromised to deliver drive-by downloads.
- Fake software updates: Pop-ups claiming “Your browser is outdated” or “Critical security patch required” that actually install malware instead of legitimate updates.
- Supply chain compromises: Third-party tools, plugins, or libraries that get infected upstream and spread infostealers to everyone who downloads them.
In each case, the infostealer needs just seconds to execute, collect its bounty, and transmit everything to remote servers controlled by criminals, which is one reason why modern infostealers have become remarkably sophisticated.
One infostealer family, called RedLine Stealer, infected 9.9 million devices worldwide before it was disrupted by law enforcement in October 2024. Its successor, Lumma Stealer, now dominates the market by also stealing active session cookies (the files used by websites to keep you logged in) in addition to passwords. With a valid session cookie, attackers can access accounts without knowing the password and potentially bypass even multi-factor authentication.
There are also popular infostealer variants, such as StealC or Lumma, that operate as malware-as-a-service and can be rented by anyone for $150-250 per month. Subscribers receive user-friendly dashboards, automatic updates, and customer support. It’s a turnkey cybercrime operation accessible to anyone with basic computer skills and a few hundred dollars, so even disgruntled employees, business competitors, or amateur criminals can launch sophisticated credential theft campaigns that once required advanced hacking skills.
Consider the Nobitex cryptocurrency exchange breach. Two employees’ computers were infected with StealC and RedLine infostealers months before the attack. The malware silently harvested admin passwords, webmail logins, and project management credentials. Attackers used this stolen access to infiltrate internal systems and ultimately steal $81.7 million from the exchange’s hot wallets.
The Underground Infostealer Credential Marketplace
Stolen credentials don’t sit idle. They fuel a thriving underground economy where your employees’ passwords become commodities traded like stocks. Each infected computer generates a “log,” which is a package containing saved passwords, cookies, autofill data, and system information.
The collected logs appear on dark web marketplaces within hours of theft, sorted by company, service type, and access level. Before its takedown in April 2023, Genesis Market alone hosted 80 million account credentials from 1.5 million compromised computers.
Modern dark web marketplaces do their best to attract vendors and buyers alike by providing what can be described as an “Amazon experience.” Buyers can search these markets like when shopping for everyday goods online and even filter the results by company name, email domain, or specific services. Basic employee credentials sell for next to nothing, while administrator accounts fetch higher prices but rarely exceed a few thousand dollars.
Most buyers of credentials stolen by infostealer malware don’t wait long before they attempt to put them to good use (they know well that credentials don’t stay valid forever). A common scenario involves ransomware operators purchasing fresh credentials and deploying encryption within hours.
Another increasingly frequent pattern involves attackers using stolen logins to execute massive data breaches. The 2024 Snowflake data breach is a prime example of this. The incident involved criminals who purchased infostealer logs containing customer credentials and systematically accessed accounts lacking MFA. Ultimately, they managed to breach over 165 organizations, including AT&T and Ticketmaster.
Infostealer Protection Best Practices
| Protection Best Practice | Key Benefits |
| Multi-Factor Authentication (MFA) | Blocks unauthorized access even with compromised passwords |
| Dark Web Monitoring | Alerts when your credentials appear for sale on criminal marketplaces |
| Enterprise Password Managers | Generates unique passwords to prevent credential reuse across services |
| Cybersecurity Awareness Training | Helps staff recognize phishing emails and fake software updates |
| Automated Software Updates | Patches vulnerabilities that infostealers exploit for initial access |
| Endpoint Detection & Response (EDR) | Catches sophisticated infostealer techniques that evade traditional antivirus |
Defending against infostealers requires implementing practical defenses that address both the technical and human elements of the threat.
Multi-factor authentication (MFA) stands as your first and most critical defense. Even if infostealers compromise passwords, MFA adds a second verification layer that blocks most unauthorized access attempts. Those who are not using any MFA at the moment should start with high-value targets: administrator accounts, email systems, financial applications, and remote access tools. Then expand coverage systematically across all accounts.
Of course, MFA alone isn’t enough. As we’ve already explained, sophisticated infostealers can steal session cookies that sometimes bypass MFA protections. Still, MFA stops the vast majority of credential-based attacks, and there are other infostealer protection best practices to address the rest, such as dark web monitoring services that alert you when employee credentials surface for sale.
Dark web monitoring services continuously scan criminal marketplaces, hacker forums, and paste sites for your organization’s email domains and login credentials. Since attackers typically exploit stolen credentials within hours of purchase, rapid detection and response are essential. The moment you receive an alert, force password resets for compromised accounts, terminate active sessions, and scan the affected employee’s device for malware.
You should also deploy enterprise password managers to generate unique, complex passwords that adhere to your password policy for every account and prevent one compromised credential from cascading into multiple breaches. At the same time, configure browsers to block password saving for sensitive applications since infostealers specifically target browser credential stores where employees carelessly save everything from personal social media to corporate admin logins.
Your staff needs to recognize the specific tactics used to deliver infostealers: fake software update prompts, malicious email attachments disguised as invoices, and “free” versions of expensive software loaded with malware. Focus cybersecurity awareness training on real scenarios employees encounter daily rather than abstract security concepts. Show them actual phishing emails your industry receives, demonstrate how legitimate software updates look versus fake ones, and explain why downloading cracked software on any device that touches company data endangers the entire organization.
Since some infostealers exploit known vulnerabilities in outdated software to gain initial access, it’s important to keep all software updated by implementing automated updates for operating systems, browsers, PDF readers, and plugins. Complement this with endpoint detection and response (EDR) solutions that catch what traditional antivirus misses, like the memory-only execution and polymorphic code techniques used by modern infostealers to evade signature-based detection.
By combining these defenses, your organization can create multiple layers of protection that work together to stop infostealer attacks at every stage. The result? Your chances of becoming the next infostealer victim drop to almost zero.
Conclusion
Infostealer malware has transformed credential theft into an industrial-scale operation where your employees’ passwords sell for less than a coffee shop latte. To protect your organization against the threat it represents, you need to act before you become its next victim. Start with the fundamentals (implement MFA, deploy password managers, and set up dark web monitoring) and then build from there with security training, regular patching, and EDR solutions. The investment required is minimal compared to the average breach cost, and the peace of mind is priceless. To get started, contact us at OSIbeyond today and schedule your free consultation.