Some industrial software companies in the UK are "likely to have been compromised" by hackers, according to a document reportedly produced by British spy agency GCHQ. A copy of the document from the National Cyber Security Centre (NCSC) -- part of GCHQ -- was obtained by technology website Motherboard. From a report: A follow-up by the BBC indicated that the document was legitimate. There have been reports about similar cyber-attacks around the world lately. Modern, computer-based industrial control systems manage equipment in facilities such as power stations. And attacks attempting to compromise such systems had become more common recently, one security researcher said. The NCSC report specifically discusses the threat to the energy and manufacturing sectors. It also cites connections from multiple UK internet addresses to systems associated with "advanced state-sponsored hostile threat actors" as evidence of hackers targeting energy and manufacturing organisations.