Right now, millions of people are unknowingly running malware disguised as their favorite Chrome extensions - collecting passwords, hijacking ad budgets, and draining cryptocurrency wallets.

How attackers actually exploit extensions

🧪 Fake-but-polished add-ons in official stores - threat groups submit lookalike or repackaged tools that pass store review, then exfiltrate cookies and data once installed.

🔐 Session hijack and MFA bypass - infostealers like Rilide run as extensions in Chromium browsers to hook pages, grab session tokens, and inject scripts - perfect for taking over crypto exchanges and dashboards without needing your OTP.

📊 Spyware dressed as “analytics” - extension-based tracking has repeatedly harvested browsing of consumers and enterprises (think: internal URLs, documents, tickets).

💸 Ad and SEO fraud at scale - malicious updates inject code to rewrite searches, swap affiliate links, and run fraudulent ads - quietly monetizing every pageview.

🧑‍💼 Business account takeovers - a digital marketing manager installs what appears to be a 'Meta Account Verification' extension—it even has positive reviews. Within 24 hours, her $5,000 monthly ad budget vanishes, and attackers are running fraudulent campaigns under her account.

In early 2025, two major campaigns emerged: GitLab discovered 16 malicious extensions affecting 3.2 million users; separately, the RedDirection campaign compromised 2.3 million users via 18 extensions across both Chrome and Edge^[ref].

👤 How can we protect ourselves:

- Choose the web browser that protects your privacy the way you expect (e.g. Brave)

- Install fewer, not more. Audit your extensions regularly; delete anything you don’t absolutely use.

- Prefer well-known vendors with source transparency and recent, legitimate changelogs.

- Watch permissions: “Read and change all data on all websites” is a red flag unless you truly need it.

- Separate risk: one “clean” browser (no extensions) for banking, a second for daily browsing.

- Log out of sensitive apps when done; short sessions reduce cookie theft blast radius.

🏢 How can we protect our organizations:

- Think of it like airport security: lock down to only approved extensions (the allowlist), block workarounds, and prevent users from installing anything outside official channels. One compromised extension can undo weeks of other security work.

- Inventory extensions via MDM/EDR; alert on new installs and high-risk permissions.

- Bind sessions to device risk and re-auth sensitive actions; rotate/expire cookies faster.

- Use Cloud Access Security Broker (CASB) or browser isolation for ad platforms and admin consoles to create a protective layer that blocks risky actions and keeps extensions from stealing sessions.

- Train marketers: “verification” and “analytics helper” extensions are a prime lure. Share indicators fast.

🚨 Browser extensions are the Trojan horse of 2025. They ask for permission once, then operate invisibly forever. The stakes aren't theoretical—millions have already been hit. Audit today.