Open the attachment in a box with no way out

Finance forwards you an invoice PDF that looks wrong. You don't open it on a laptop.

You clone the analysis container from its snapshot, then PUT /network with type: block. The exit is enforced on the host, outside the container: nothing inside can add a route, fall back to direct egress, or phone home. You drop the file in and open it on the container's display URL, in a browser tab, watching the desktop.

The macro runs. It tries to fetch a second stage. It gets nothing. You snapshot the box as it sits, compare it against the clean snapshot to see what it wrote, and delete the container.

No sandbox appliance, no air-gapped laptop in a drawer, no vendor detonation service with a per-sample bill. The detonation chamber is a container whose exit is set to block.

The detonation chamber is a container whose exit is set to block.