Browser extensions have access to everything you do online. A malicious extension can read your passwords, replace wallet addresses, and drain your funds.
How Extensions Can Steal Crypto
| Method | How It Works |
|---|
| Clipboard hijacking | Replaces copied wallet addresses |
| Form reading | Captures passwords and seed phrases |
| Session hijacking | Steals login cookies |
| Mutual pinning | Injects malicious code into websites |
| Screen capture | Records your screen |
High-Risk Extension Categories
| Category | Risk |
|---|
| Unverified crypto wallets | Direct wallet access |
| Clipboard managers | Can read copied addresses |
| Screen recorders | Capture everything |
| Unknown ad blockers | Often inject ads |
| PDF tools | Broad permissions |
Red Flags
| Red Flag | What to Check |
|---|
| Very few users | Under 10,000 installs |
| No privacy policy | Developer doesn’t explain data handling |
| Requests broad permissions | ”Read all data on all websites” |
| Recent and unproven | Launched days ago |
| Poor reviews | Reports of suspicious behaviour |
| Developer unknown | No website or contact |
Safe Extension Practices
| Practice | Why |
|---|
| Install only from official stores | Chrome Web Store, Firefox Add-ons |
| Check developer | Known company or developer |
| Check ratings and reviews | Real users report issues |
| Minimise extensions | Fewer extensions = lower risk |
| Review permissions regularly | Remove what you don’t need |
Extension Permissions to Watch
| Permission | Risk |
|---|
| ”Read and change all your data on all websites” | Maximum risk |
| ”Access your tabs” | Can see what sites you visit |
| ”Read clipboard” | Can read copied addresses |
| ”Capture screen” | Can record your activity |
A crypto wallet extension needs “Read and change data on all websites” to function. That’s normal. But a calculator extension doesn’t need it.
The Wallet Extension Approach
| Best Practice | Why |
|---|
| Use wallet extensions from official sources | Metamask.io, not a third-party |
| Pin the extension | See what it’s doing |
| Revoke connections regularly | Clean up old dApp connections |
| Use burner wallet for browsing | Separate from main holdings |
| Disable when not using | Reduce attack surface |
What to Do If You Suspect a Bad Extension
| Step | Action |
|---|
| 1 | Remove the extension immediately |
| 2 | Change passwords for all crypto services |
| 3 | Revoke wallet connections |
| 4 | Scan your computer for malware |
| 5 | Use a clean browser for the next few days |
Bottom Line
Browser extensions have broad access. Only install what you need, from verified developers, with clear privacy policies. A crypto wallet extension is necessary but everything else should be minimised. Review your extensions monthly. A clean browser is a safe browser.
This content is for educational purposes only. Not financial advice. Do your own research before investing.