wiring-sbx-mcp-servers

MEDIUM W012: Unverifiable external dependency detected (runtime URL that controls agent).

• Potentially malicious external URL detected (high risk: 0.90). The guidance shows registering a remote MCP endpoint (https://slack.example.com/mcp) via sbx mcp add --url, which the gateway connects to at runtime and can supply tools/prompts or invoke remote-executed behaviors that directly control agent instructions.

MEDIUM W013: Attempt to modify system services in skill instructions.

• Attempt to modify system services in skill instructions detected (high risk: 1.00). The skill explicitly instructs running sbx mcp add (which writes host-side registrations), running host-run servers (--command/--local) that execute outside sandbox isolation with full filesystem/network access, and storing OAuth client secrets in the host credential store — all actions that modify host state and can compromise the machine.