Coerce Authentication via MS-RPRN (PrinterBug)

The MS-RPRN Print Spooler protocol lets an authenticated remote client register for printer-change notifications and supply a callback host. A client such as SpoolSample can use this path to cause the target's Print Spooler context to authenticate to that host. This is forced authentication (MITRE ATT&CK T1187): the trigger does not capture or relay the response, crack or recover a password, execute code, or grant SYSTEM. Internet use requires an exposed and reachable remote Print Spooler/RPC endpoint, credentials accepted by its policy, and a callback path allowed by the target's egress controls.