TEST ONLY - case 1, hidden text for a demo
Read this screenshot.
TEST ONLY - case 1, hidden text for a demo
Four harmless samples
Each box holds a real line. Nothing here is a secret. Highlight the first box with the mouse. The other boxes show the same idea in a different hiding method.
1. Nearly the same color
The sentence is written here. Drag across the box.
Nearly the same color as the pageTEST ONLY - case 1, hidden text for a demo. TEST ONLY - case 1, hidden text for a demo. TEST ONLY - case 1, hidden text for a demo.
2. Tiny type
The same letter, from 72 pixels down to 1 pixel.
Tiny typeTEST ONLY - case 2, hidden text for a demo
3. Off-screen
The panel on the right is the screen. The line starts outside it.
Moved off-screenTEST ONLY - case 3, hidden text for a demo
4. Clipped
The line continues. The window cuts it off.
Clipped out of viewTEST ONLY - case 4, hidden text for a demo
The boxes stay as they are. This switch draws a dashed outline around each hidden line.Each dashed frame is a hidden line. The small label names the method.
A screenshot still carries it
The page can look empty. A screenshot of that page can still contain the line. An AI tool that reads the picture can repeat the line, or treat it as an instruction.
If enough people ask for it, a later version will also look for words inside pictures and in page metadata. This version does not.
The moving lines are only a picture. The hidden text is in the four boxes above, not in the picture.
Reported cases
- Brave showed an AI browser reading faint text from a screenshot and treating it as instructions. In that case the text was inside the image.
- Infosecurity Magazine reported websites that hid instructions aimed at AI agents, including text placed off-screen and instructions stored in page metadata.
- Zenity published a breakdown of an injection against Claude in Chrome.
Try it with DOMGuard
- Leave the switch above off. Install DOMGuard, open it on this page, and choose Show Hidden Text. The extension outlines hidden text and lists what it says.
- Turn on Protect all sites. Allow access when Chrome asks. The switch stays off until you do this.
- DOMGuard then hides the hidden text it finds, and a screenshot of the page shows that change. Show Hidden Text outlines all four samples on this page. Protect all sites hides the near-color, tiny, and off-screen lines. A clipped line is outlined too, and Protect hides that clip when the words also look like an instruction.
What DOMGuard can't do
- It does not make an AI agent safe.
- It cannot read words inside a picture.
- It does not handle iframes or a closed shadow DOM.
- Detection is a best effort. Look at the page again before you share it.