What if the “productivity booster” you installed is quietly stealing your session cookies, hijacking ad spend, or watching every click?

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 - fake “Meta verification” or “analytics” extensions targeted marketers, stealing Facebook session cookies and raiding ad budgets within hours.

At least 3.2 million users were hit by a single 2025 cluster of malicious Chrome extensions - all originally offered “useful” features. Another campaign logged over two million installs across 18 extensions in Chrome/Edge web stores. Store presence isn’t a safety guarantee^[ref].

👤 How can we protect ourselves:

- 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:

- Enforce allowlists via browser/endpoint management (Chrome Enterprise/Edge policies); block installs outside the store and disable Developer Mode.

- 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.