Web browsers handle a lot of sensitive data. Your employees use them to access cloud applications, authenticate to internal systems, and store the credentials that keep business running. Unfortunately, browsers also happen to be where infostealers do their most damage.
While these malicious programs might arrive through various attack vectors, they consistently target browsers for one simple reason: that’s where the good stuff lives. Stored passwords, session cookies, authentication tokens, and saved payment information all sit in browser databases that infostealers are specifically designed to pillage.
The frustrating part for IT teams is that most browser security vulnerabilities aren’t even vulnerabilities in the traditional sense. They’re features working exactly as designed, just in ways that benefit attackers more than users. Default browser configurations prioritize convenience over security, creating a perfect storm for credential theft.
Browser hardening won’t stop infostealers from landing on your endpoints, but it can slam the door shut on their primary objective: stealing your users’ stored credentials and session data.
Why Infostealers Love Default Browser Settings
Modern browsers are incredibly complex applications. Chrome runs on millions of lines of code, and every feature designed to make browsing easier also creates new opportunities for data extraction.
Verizon’s data breach investigations showed that stolen credentials remain a leading factor in successful breaches. When employees use browsers with default settings, they’re maintaining detailed inventories of authentication data that infostealers can harvest with minimal effort.
Most users never venture beyond these defaults. They install their browsers, perhaps import bookmarks, and start working. Every saved password and remembered login becomes potential ammunition for the next infostealer campaign that lands on their machine.
The Risk of Browser-Stored Credentials
Infostealers don’t even need administrative privileges to access most browser data. They can extract passwords, cookies, and session tokens from standard user accounts because browsers store this information in locations accessible to any process running under the user’s context.
This creates a perfect scenario for credential theft. Even if your endpoint detection tools catch and remove the infostealer itself, the damage is already done. The risk extends past individual compromises:
- Stolen credentials often lead to lateral movement within networks
- Password reuse amplifies impact across multiple business and personal accounts
- Harvested session cookies can bypass multi-factor authentication requirements
- A single successful harvest can provide attackers with access to cloud applications and email systems
What starts as one infected endpoint can quickly become an organization-wide security incident.
Browser Hardening Fundamentals That Reduce Risk
These browser hardening changes will stop most infostealers from getting what they came for. Start with these five areas and you’ll eliminate the biggest targets that malware goes after first.
1. Eliminate Built-in Password Storage
Browser password managers represent the lowest-hanging fruit for infostealers. These systems store credentials in local database files that malware can easily access and extract. While convenient for users, they’re gift-wrapped packages for credential harvesting operations.
Deploy dedicated password management solutions instead. Enterprise tools like Bitwarden Business, 1Password Business, or similar platforms store credentials in encrypted vaults that require additional authentication to access. These solutions also generate unique, complex passwords for each application, limiting the impact of any single credential compromise.
Configuration steps for common browsers:
- Chrome: Set “PasswordManagerEnabled” policy to false
- Firefox: Disable “signon.rememberSignons” preference
- Edge: Use “PasswordManagerEnabled” administrative template
- Safari: Disable “AutoFillPasswords” in configuration profiles
2. Control Cookie and Session Data Retention
Persistent cookies and stored session data provide infostealers with ready-made authentication tokens that can bypass multi-factor authentication requirements. By harvesting these artifacts, attackers can impersonate legitimate users without needing to authenticate through normal channels.
Configure browsers to clear cookies and site data when users close their sessions. This limits the window of opportunity for infostealers to harvest usable session tokens. For applications that require persistent authentication, consider implementing shorter session timeouts and more frequent re-authentication requirements.
Use “CookiesSessionOnlyForUrls” policy to control which sites can maintain persistent sessions while forcing others to clear data on browser closure.
3. Restrict Automatic File Handling
Infostealers often arrive disguised as legitimate downloads or bundled with software that users willingly install. Browser settings that automatically handle downloaded files can accelerate the infection process by reducing the number of user interactions required to execute malicious code.
Disable automatic downloads and file execution across all managed browsers. Force users to explicitly choose download locations and file handling actions. While this creates additional friction in the user experience, it provides opportunities for users to reconsider suspicious downloads.
Key configuration changes:
- Disable automatic downloads for all file types
- Require user confirmation for file execution
- Configure download location prompting
- Integrate with endpoint protection for real-time file scanning
4. Manage Extension Permissions and Access
Browser extensions create additional attack surfaces through third-party code that often requests broad permissions. Malicious extensions can function as persistent infostealers, continuously harvesting data from users’ browsing sessions. Even legitimate extensions can become compromised, turning them into data collection tools for attackers.
Implement extension whitelisting policies that allow only approved extensions from trusted developers. Use enterprise browser management tools to deploy and configure extensions centrally rather than allowing users to install them individually.
Regularly audit extension permissions and remove any that request access to sensitive data without clear business justification. Extensions that can read data from all websites, access browsing history, or modify web content pose particular risk in enterprise environments.
5. Enable Advanced Safe Browsing Features
Modern browsers include threat intelligence capabilities that can identify and block known malicious websites and downloads. Enhanced safe browsing features use real-time reputation data to warn users about potentially dangerous content before they interact with it.
Enable these protections at their highest levels across all managed browsers. Google’s Enhanced Safe Browsing, Microsoft’s SmartScreen, and similar features provide additional protection against drive-by downloads and malicious websites that might host infostealer payloads.
Configure these systems to report threat telemetry back to your security team. This data can help identify users who are encountering malicious content and may require additional security awareness training or endpoint monitoring.
Advanced Browser Hardening Strategies
Once you’ve implemented the fundamentals, additional hardening techniques can provide deeper protection against sophisticated infostealer campaigns and advanced persistent threats targeting your browser infrastructure.
Implement Site Isolation and Sandboxing
Modern browsers include process isolation features that separate content from different websites into distinct memory spaces. Site isolation makes it significantly harder for malicious scripts on one website to access data from other sites that users have open simultaneously.
Enable these features through group policies and browser configuration management tools. Chrome’s site isolation feature, for example, can be enforced through the “SitePerProcess” policy setting. Similar capabilities exist in other browsers and should be activated consistently across your environment.
Consider supplementing browser sandboxing with additional application isolation tools. Solutions like Windows Defender Application Guard or third-party browser isolation platforms can provide additional layers of protection against sophisticated attacks.
Control Script Execution and Active Content
JavaScript and other active content represent common delivery mechanisms for infostealers and other malware. While completely blocking scripts would break most modern web applications, you can implement more granular controls that reduce risk without eliminating functionality.
Deploy content filtering extensions or configure built-in browser features to block scripts from untrusted sources. Tools like uBlock Origin can provide enterprise-grade content filtering when properly configured and centrally managed.
Block scripts from newly registered domains, implement whitelist-based script execution for sensitive environments, and use content security policies for internal applications to limit the attack surface available to malicious content.
Monitor and Log Browser Security Events
Browser hardening doesn’t stop at prevention; it also covers detection and response. Configure logging and monitoring systems that can identify when users encounter malicious content or when browser security policies are violated.
Enable detailed browser logging through group policies and centralize these logs in your SIEM or security monitoring platform. Events like blocked downloads, policy violations, and safe browsing warnings can provide early indicators of potential infostealer campaigns targeting your organization.
Implement user behavior analytics that can identify unusual browsing patterns or credential usage that might indicate successful infostealer infections. Changes in login locations, unusual application access patterns, or simultaneous logins from multiple locations can all signal compromised credentials.
Balancing Security and User Experience
The biggest challenge in browser hardening is maintaining user productivity while implementing meaningful security controls. Overly restrictive policies that break legitimate business applications will face user resistance and may be circumvented through shadow IT practices.
Start with high-impact, low-friction changes like disabling password storage and enabling safe browsing features. These modifications provide significant security benefits without dramatically altering the user experience. Gradually implement additional controls as users adapt to the new security posture.
Create different security profiles for different user groups and risk levels. Developers might need more permissive browser configurations to test web applications, while general users can operate effectively with more restrictive settings. Executive users who handle sensitive data might require additional hardening measures.
Document your browser security policies and provide training on why these controls matter. When users understand the risks they’re protecting against, they’re more likely to embrace security measures even when they create minor inconveniences.
The Role of Endpoint Privilege Management
Browser hardening becomes even more effective when combined with proper endpoint privilege management. Infostealers that can’t gain elevated access to the operating system have limited ability to install persistence mechanisms or access system-level credential stores.
Our EPM solution complements browser hardening by ensuring that infostealers can’t escalate privileges to access additional credential sources or install system-level persistence mechanisms. When users operate without permanent administrative rights, the impact of successful infostealer infections is significantly contained.
Just-in-time privilege elevation also provides opportunities to detect and block malicious activity. When software requests administrative privileges, security teams can evaluate whether the request is legitimate or potentially malicious.
Browser Hardening in Practice
Most infostealers succeed because they find what they’re looking for immediately. Stored passwords sitting in browser databases, session cookies ready to be harvested, and automatic file handling that makes infection easier.
Remove those easy wins and infostealers have to work much harder for much less payoff. It’s like removing admin rights – you’re not stopping every attack, but you’re making successful attacks harder while reducing the potential for damage.
