But no changes were made to the code, Microsoft asserts
But none of the company's products or services were affected, Cisco says
The spyware exploited an iMessage vulnerability in iOS
The company says such features were only used 'within a testing environment'
But the major target was the US government
CISA has warned about the difficulty of completely ridding the government network of malware
Facebook has taken out full-page ads in the US press claiming opt-in permissions will hurt small businesses
But hackers may still have other means to retain access to victim networks, security experts warn
Update to remove malware planned for release today