The Chinese state-sponsored group APT41 has been at the helm of a range of attacks that used recent exploits to target security flaws in Citrix, Cisco, and Zoho appliances and devices of entities from a multitude of industry sectors spanning the globe. The group is a highly prolific Chinese backed hacking group active since at least 2012 and known for espionage, cybercrime, and surveillance operations against a large array of industries. The hiatus intervals coincide with Chinese holidays or with quarantine measures taken by the Chinese government in response to the COVID-19 pandemic.
Source: https://www.bleepingcomputer.com/news/security/chinese-hackers-use-cisco-citrix-zoho-exploits-in-targeted-attacks/