security: authenticate RPC socket and validate route registration#8
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security: authenticate RPC socket and validate route registration#8
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- Generate a shared secret at startup, write to /tmp/backoffice-rpc.secret - Require secret in every RPC call (timing-safe comparison) - Validate route targets are localhost only (http://localhost:<port>) - Restrict route patterns to allowlist (/share) - Share skill reads secret from file before RPC calls Prevents background processes from hijacking routes or proxying to internal/cloud metadata endpoints.
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Problem
Any process running as
appuser(including anything spawned viashell) can connect to the internal Unix socket at/tmp/backoffice.sockand register arbitrary HTTP routes. This means a compromised or malicious background process could:/mcpand intercept all MCP traffic (including OAuth tokens)http://169.254.169.254to access cloud metadataChanges
src/rpc.tsrandomBytes(32)shared secret at startup, written to/tmp/backoffice-rpc.secret(mode 0600)params.secret— rejected via timing-safe comparison if missing/wrong/^http:\/\/(?:localhost|127\.0\.0\.1):\d+$//share)skills/share/index.ts/tmp/backoffice-rpc.secretbefore RPC callsroute.registerandroute.unregisterparamsTypechecks clean.