Capture & Replay
How VexSolver achieves sub-second solves.
The core insight
Most bot-detection vendors issue a single "interrogation" payload the first time a browser loads the page. That payload is a function of a handful of rotating script constants and a large, mostly-static fingerprint. Once our engine has captured one valid interrogation from a given version of the target's challenge script, we can replay it — with fresh timestamps and a rotated session tag — indefinitely, until the script version changes.
Cache miss: full capture
On a cache miss we spin up our internal bridge (JSDOM for Imperva, V8 sandbox for Akamai, etc.) to generate the first payload. This takes 4-8 seconds. The resulting template is stored on disk — not in memory — so it survives service restarts.
Cache hit: native replay
On a cache hit we reconstitute the payload from the stored template in under 10ms of pure Go. The replay path includes:
- › Fresh timestamp injection
- › Session tag rotation
- › Sensor field mutation (where required)
- › Re-signing with the vendor's crypto primitives