A browser extension is a software module that adds specific features or functionality to a web browser.
Extensions can modify browser behavior, interact with web pages, manipulate content, and integrate with external services. They range from popular password managers and ad blockers to specialized developer tools, productivity applications, and AI agent interfaces that enable LLM-powered assistance directly in the browser.
How Browser Extensions Work
Browser extensions operate through a permission-based model. During installation, they ask for access to various browser capabilities. Modern extensions typically use APIs like Chrome Extension API or WebExtensions API to interact with browser tabs, cookies, local storage, and network requests.
Once installed, they run continuously with those granted permissions, which means they can:
- Intercept network requests.
- Modify the content you see on a web page (DOM elements).
- Communicate with external servers.
- Access AI service APIs. Extensions connecting to LLMs often store or transmit API keys for services like OpenAI, Anthropic, or Google.
AI-powered browser extensions introduce an additional identity layer. These extensions often embed LLM agents that act on behalf of the user, reading page content, summarizing information, interacting with SaaS tools, or performing automated workflows. To do this, they maintain persistent connections to external AI APIs and may store user-linked or workload-linked API keys locally or in extension storage.
When the agent interacts with enterprise systems through the browser, its actions occur under a blended context: the user’s authenticated session combined with the extension’s machine-level access to APIs. This makes AI agent extensions a high-risk identity surface, because they can inherit both the privileges of the logged-in user and the capabilities of the external AI service they connect to.
Why Browser Extensions Matter
Enterprises face a significant challenge as employees install browser extensions to boost productivity, often without IT oversight.While some extensions are valuable, others create substantial security risks that most organizations haven’t addressed.
The browser has become the primary workplace interface. Employees access SaaS applications, cloud consoles, internal tools, and customer data entirely through their browsers. A malicious browser extension compromises that entire environment.
For organizations deploying AI agents or managing hybrid workloads, browser extension security becomes even more critical.
Development teams use browser-based IDEs, security teams manage cloud infrastructure through web consoles, and AI systems increasingly interact with browser-based tools. A compromised extension in this context can expose API keys, capture OAuth tokens, or intercept credentials for non-human identities.
Common Challenges with Browser Extensions
- Credential Exposure: Browser extensions can intercept sign-in flows, capture forms, and access stored credentials, including service accounts and API tokens that developers use in browser-based tools.
- Shadow IT Proliferation: Employees install extensions to solve problems without IT oversight. This creates ungoverned access points that bypass your standard security controls.
- Excessive Permissions: Many extensions request broad permissions that go far beyond their core function (e.g., access to “all websites”). Users often approve these without understanding the massive amount of access they are granting.
- Supply Chain Attacks: This is insidious. Legitimate extensions get compromised after being acquired by malicious actors or through developer account takeovers. A previously safe extension can turn into malware after an automatic update.
- Limited Visibility: Most organizations simply can’t see which extensions employees have installed or detect suspicious activity until after a breach has occurred.
Securing browser extensions requires a combination of technical controls, user education, and security architectures designed to limit credential exposure. Organizations should implement extension policies, monitor for risks, and assume that browser environments will eventually be compromised.
FAQ
You Have Questions?
We Have Answers.
What permissions should I watch for when reviewing browser extensions?
Review extensions requesting access to “all websites,” ability to read and change data on pages you visit, or permissions to capture network requests. Extensions needing these broad permissions should provide clear justification for why their functionality requires such access.
How do malicious browser extensions typically compromise enterprise security?
Malicious extensions often operate as keyloggers capturing credentials during login flows, inject code into legitimate sites to phish users, exfiltrate data from internal tools to external servers, or modify web traffic to redirect payments and API calls. Some extensions appear legitimate initially but change behavior after updates.
Can browser extension risk be mitigated without blocking all extensions?
Yes, through allowlisting approved extensions, implementing access controls that don’t rely on browser-stored credentials, monitoring extension behavior, and educating users about permissions. The goal is reducing credential exposure while maintaining functionality.
Do enterprise browser management solutions fully solve browser extension security?
Enterprise browser management helps by controlling which extensions can be installed and enforcing policies, but doesn’t eliminate risk entirely. Supply chain attacks can compromise even approved extensions. Complementary controls that eliminate credential storage in the browser provide deeper defense.