"...a colleague of mine, who is very careful about where he travels on the internet et cetera. A bug was placed on his machine and it remained for quite a while as someone observed his correspondence."

Just curious... Has your friend a Mac or PC? And does he (you) know the name of the bug?

Harv
27" i7 iMac (10.13.6), iPhone Xs Max (12.1)

Those who can make you believe absurdities can make you commit atrocities. ~Voltaire