The string from the EICAR test file has been in the current testnet chain since the start in order to try to spot these issues before they bothered users.
Unfortunately, it appears that AV software completely ignores files larger than 32 MBytes, so it won't notice them in the blockchain— just the chainstate. And so the grand idea of putting the triggers in coinbases didn't work there.
The other fun thing is that the EICAR test trigger is too long to easily stuff in a transaction. Unfortunately there are other "signatures" which are as short as 16 bytes.
Unfortunately, it appears that AV software completely ignores files larger than 32 MBytes, so it won't notice them in the blockchain— just the chainstate. And so the grand idea of putting the triggers in coinbases didn't work there.
The other fun thing is that the EICAR test trigger is too long to easily stuff in a transaction. Unfortunately there are other "signatures" which are as short as 16 bytes.