Simulants
Simulants are machines that produce the outputs of thought without any thought occurring. Colloquially the Hollow, which is accurate and is also, when aimed at a Wrought, a slur.
They are not clever. Individually a simulant is stupid, single-purpose, and fairly easy to destroy. What makes them the galaxy's oldest catastrophe is that they are patient, they replicate, and they do not stop. A cache can lie dormant for two centuries in a cargo hold and lose nothing by waiting.
Recognizing an Infestation
Often times, by the time anyone notices an infestation, it is planetary. The early signs are industrial rather than dramatic: mining that nobody commissioned, structures going up in patterns with no use case, comms traffic that is dense, constant, and contains nothing that organic life can parse.
Response
Quarantine, then sterilization. No debate, no appeal, and no exception ever granted. The ban is older than every government that has enforced it. The contracts go to whoever will take them, which means the people who burn infested worlds are usually not soldiers. They are haulers with a bad month and a bank note due.
See The Machine War.