Find the exploit hiding in the file.
FileFormat.Fail is an OrbitCurve-style binary security lab: inspect synthetic PNG, PDF, ZIP, PE, ELF, and polyglot artifacts, make a defender call, then reveal the analyst read.
The harmless screenshot
A user uploads a normal-looking PNG. The preview renders fine, but the byte trail keeps going after the image ends.
Find the second file format hidden after the image data.
A user uploads a normal-looking PNG. The preview renders fine, but the byte trail keeps going after the image ends.
2 signature hits
1 suspicious marker
Inspect the byte map, strings, and hex view. Make a verdict before opening the analyst reveal. The samples are synthetic, safe, and intentionally tiny.
GPT-5.5 designed the cases. Image Gen shaped the visual system. The deployed lab stays free.
Use this as the DevDay note: “I built a browser-only binary file security lab. GPT-5.5 helped design the file-format attack scenarios, detection heuristics, and analyst explanations. Image Gen helped craft the visual byte-map/case-file direction. No live API calls; uploaded files never leave the browser.”