Taming Browser Extensions: How Businesses Can Reduce the Security Risk

Browser extensions are a part of everyday work – but they also create a quiet, powerful pathway into your organisation’s data and systems. This article explains what they are, how attackers use them, the real risk to your business, and how to manage them on both corporate and BYOD devices.

What browser extensions actually do?

Browser extensions are small software add‑ons that sit inside Chrome, Edge, Firefox and other browsers to add extra features. Staff use them to:

• Save passwords and fill forms.
• Block ads and trackers.
• Connect to cloud apps like CRM, project tools or AI writing assistants.
• Capture screenshots or record meetings.

To do this, extensions often need deep access to pages, cookies, and even stored credentials. That access is what makes them useful – and what makes them dangerous if things go wrong.

Why should I care?

• Your data may be flowing through tools you have never heard of.
• A single compromised user can provide a route into shared systems, customer records or finance platforms.
• Even non‑malicious extensions can create compliance issues if they collect or transmit regulated data without controls.

In short, unmanaged extensions quietly expand your attack surface across both corporate and personal devices and generally are not monitored or scanned by Anti-Virus or malware packages - leaving your browser (and associated data) exposed.

How attackers use browser extensions

Attackers treat the browser as a high‑value target because it’s where users log in, approve payments and access cloud systems. Browser extensions give them several practical attack paths.

Common attack vectors

1. Malicious extensions
   Threat actors publish extensions that look useful but are built to steal data, inject ads or redirect traffic to phishing sites. They can read page content, capture keystrokes or skim payment details in real time.
2. Supply‑chain and publisher hijack
   A legitimate extension may be sold to a new owner or have its developer account compromised, and a later update quietly adds malicious code. Because staff already trust the extension, the new behaviour often goes unnoticed.
3. Excessive permissions
   Many extensions request “read and change all your data on all websites” even when they only need limited access. Once granted, those permissions can be abused to monitor behaviour, harvest credentials or access internal portals opened in the browser.
4. Data exfiltration and shadow integrations
   Extensions can send page content, tokens or form entries to remote servers without visible signs to the user. This can bypass traditional perimeter tools and DLP rules that focus on email or file transfers.

New exploit techniques

Recent research has shown attacks like DOM‑based extension clickjacking, where hidden web page elements trick users into triggering privileged extension actions, especially in password managers. This can expose credentials without directly compromising the password manager backend.

These techniques work well on both managed and BYOD devices because they ride on top of normal browser use.

Real risk to the business

The risk is not theoretical – it shows up in four clear impact areas.

1. Data loss and privacy breaches

Extensions with high permissions can access customer records in web apps, internal dashboards, cloud storage links and even email content opened in the browser. If that data is captured or logged externally, the organisation may face:

• Reportable data breaches under privacy laws.
• Contract breaches with clients that require specific controls.
• Loss of competitive information or IP.

2. Credential theft and account takeover

An extension that can read page content or intercept form submissions can harvest usernames, passwords and session cookies. Attackers can then:

• Log into cloud systems as a valid user.
• Bypass multi‑factor in some cases by using stolen session tokens.
• Move laterally across systems, escalating privileges over time.

3. Ransomware and broader compromise

Once attackers have access via stolen credentials, they can deploy malware, encrypt shared drives or manipulate business processes such as invoicing or payroll. An extension itself may also attempt to download further payloads or redirect browsers to exploit kits.

4. Compliance and audit exposure

If an unvetted extension mishandles regulated data, the legal liability sits with your organisation, not the extension author. Poor control over extensions can also be flagged in audits for information security frameworks and client due‑diligence reviews.

For business leaders, the key point is that therisk profile of extensions is now comparable to that of unmanaged apps or shadow IT platforms – but often with far less visibility.

Managing extensions

You do not need to ban extensions outright. A structured, risk‑based approach can keep productivity benefits while reducing exposure.

Core principles for all organisations

Apply these foundations regardless of size or device type:

1. Define an extension policy
   Set a clear position on which browsers are supported, who can install extensions, and what categories are allowed or blocked. Make it short, plain and easy to follow.
2. Build an approved list
   Maintain a curated catalog of permitted extensions (for example, password managers, ad blockers, accessibility tools) and block or review everything else. Review permissions and publisher reputation before approval.
3. Limit permissions and scope
   Favour extensions that restrict access to specific sites or functions rather than “all websites.” Where available, configure policies so extensions cannot run on sensitive portals like banking, EHR, finance or admin consoles.
4. Monitor and review regularly
   Run regular audits to identify what extensions are installed, who is using them and whether they are still maintained by the vendor. Remove outdated or sideloaded extensions that have not been updated in a long time.
5. Educate staff
   Explain the risk in simple terms: extensions can see what you see, and sometimes more. Encourage staff to request tools through IT rather than installing whatever they find in the store.

Corporate‑owned devices

On managed laptops and desktops you can take stronger technical control.

1. Use central browser management
   Tools like Microsoft Group Policy, Intune, or other management platforms can enforce which extensions are installed, blocked or required across Edge and Chrome. This keeps behaviour consistent and reduces one‑off exceptions.
2. Enforce a “block by default, allow by request” model
   Block new extensions by default, with a simple process for staff to request business‑justified tools. This shifts the default from open to controlled, without stopping useful innovation.
3. Integrate with identity and endpoint security
   Link browser policies to identity systems so access and extension rights reflect role, seniority and risk level. Ensure endpoint protection can flag suspicious extension behaviour as part of your wider threat picture.
4. Align with wider security and continuity planning
   Treat major extension issues – such as a widely used tool going rogue – as part of your incident response and business continuity planning.

BYOD and personal devices

You have less control over personal devices, but you are not powerless.

1. Set clear conditions of use
   If staff access corporate systems from personal devices, make conditions part of your acceptable use and remote‑work policies. This should cover acceptable browsers, MFA requirements and high‑risk extension categories that are not permitted when accessing business systems.
2. Use secure access gateways or virtual desktops
   Where risk is higher, provide web access through virtual desktops or browser isolation so sensitive apps are never directly exposed to the local browser or its extensions.
3. Apply least‑privilege access
   Limit what BYOD users can reach: give access only to what they need, and avoid granting admin functions from personal devices. This reduces the blast radius if an extension on that device is compromised.
4. Encourage device‑level protections
   Promote up‑to‑date operating systems, modern browsers, and basic endpoint security on BYOD devices as standard expectations.

Practical starting steps by organisation size

All Organisations

• Pick one primary browser and document a simple extension policy.
• Create a short approved list and remove everything else from corporate devices.
• Run a quarterly review of installed extensions and provide a short staff briefing.

Growing organisations

• Use MDM or endpoint management to control browser and extension settings on corporate devices.
• Implement a request and approval workflow for new extensions.
• Segment access for BYOD, limiting sensitive systems to managed devices where possible.

Enterprise organisations

• Stand up a formal browser and extension governance capability as part of your security program.
• Integrate extension telemetry into your security operations, so high‑risk behaviour is visible alongside other alerts.
• Conduct regular risk assessments focused on permissions, publisher reputation and usage across business units.

Turning a blind spot into a managed asset

Browser extensions will remain central to productivity and user experience in modern workplaces. As a leader, your role is not to fight that reality, but to turn an unmanaged risk into a controlled part of your security and compliance posture through clear policy, smart technical controls and ongoing awareness.

Microsolve's support and Cyber engagements evaluate the true risk from browser extensions and provide you will clear guidance on the path forward.