Four thousand websites, including those of the U.S. federal court system, the British National Health system and other government sites, have infected visitors with cryptocurrency mining malware, the U.K. National Cyber Security Centre said Monday.

What actually happened? Hackers embedded the CoinHive malware in a third party component, Texthelp Browsealoud, advertised as adding speech, reading, and translation software to websites "for people with Dyslexia, Low Literacy, English as a Second Language, and those with mild visual impairments."