Stealer Logs: The Hidden Threat to Your Vendor Ecosystem

The staggering scale of credential theft is changing the third-party risk landscape forever. Here's what you need to know. 

The Alarming Reality of Stealer Logs 

2025 is rapidly becoming the biggest breach year on record, and stealer logs are at the heart of this cybersecurity crisis. If you haven't been paying attention to this threat, now is the time to start. 

What are stealer logs? 

Stealer logs are the output from information-stealing malware that infects users' devices and extracts saved credentials, documents, tokens, and cookies. Where previously these details weren't easily searchable, they now expose usernames, passwords, and—most critically—URLs that reveal exactly which services those credentials access. Recently, Troy Hunt, the security researcher behind Have I Been Pwned, processed over 23 billion rows of data from Alien stealer logs alone. The scale is unprecedented, but what makes this particularly dangerous for your vendor risk program isn't just the volume—it's the context. 

Why This Matters for Your TPRM Program 

When an employee at one of your vendors gets infected with stealer malware, it's not just capturing their personal email password—it's harvesting their login to: YOUR customer portal YOUR API services YOUR administrative interfaces In this scenario, your organization hasn't been breached directly, but your vendor has, leaving your systems vulnerable through the backdoor. 

What's exposed in stealer logs? 

From a third-party risk perspective, stealer logs are revealing: Vendor employee credentials to client portals Login details for administrative systems Credentials for shared resources Access to password-protected sites and services 

Access to documentation and security controls With these stealer logs being traded openly on dark web markets, organizations are discovering that credentials they thought were secure—even those behind proper authentication systems—are compromised. 

The Critical Importance of MFA 

This threat landscape underscores why multi-factor authentication is no longer optional. MFA is an absolute requirement, not a nice-to-have, alongside a good password manager that creates unique passwords for each login. While stealer logs primarily capture usernames and passwords, MFA adds that crucial additional layer of protection that can prevent unauthorized access even when credentials are compromised. 

Protecting Your Organization and Vendor Ecosystem 

Start with visibility 

You can't protect what you can't see. Every organization should register for Have I Been Pwned's domain monitoring service at haveibeenpwned.com/API/Key to receive alerts when your company domains appear in breaches. But that only covers your organization—what about your vendors? 

Evolve your third-party risk management approach 

This is where Vendifi comes in. Our platform automatically monitors not just your organization but your entire vendor ecosystem for exposure in breaches and stealer logs through: 

1. Continuous Vendor Monitoring: We scan for your vendors' domains appearing in breach data, including stealer logs. 

2. Automated Risk Scoring: When a vendor's credentials appear in stealer logs, their risk score is automatically adjusted, and you're immediately notified. 

3. Streamlined Response Workflows: Pre-configured workflows can automatically trigger vendor assessments when credentials are exposed. 

4. Evidence Collection: Easily gather documentation of remediation from affected vendors. 

5. Email Security Verification: We verify email security protocols to prevent further phishing attacks—the primary vector for stealer malware.

Beyond monitoring: Proactive protection 

Monitoring alone isn't enough. You need to take proactive steps to reduce your exposure: 

• Implement strict vendor access controls 

• Require hardware MFA keys for sensitive systems 

• Set shorter session timeouts 

• Monitor for anomalous login patterns 

• Establish clear breach notification requirements in vendor contracts Vendifi helps you manage these requirements and track compliance across your entire vendor ecosystem. 

The New Reality of Vendor Risk 

The threat landscape has fundamentally changed. It's no longer enough to assess your vendors once a year and hope for the best. Data breaches and stealer logs have created a continuous threat that requires continuous monitoring. Whether you're using Vendifi or building your own monitoring program, you need to start today. Your vendors' credentials are likely already for sale, and the clock is ticking. This isn't just a technical problem—it's a business risk that demands immediate attention from every organization with a digital supply chain.  

Want to learn more about protecting your organization from the threats posed by stealer logs? Contact our team to schedule a demo of Vendifi's third-party risk management platform.