Security is a complex field my friend. What would you say is your background in security? Do you have an idea on how to protect your computer's files, accounts, etc? In any case of that, I would read Lopp's guides on security:
https://www.lopp.net/bitcoin-information/security.html.
Could recent 'ordinals' congestion be considered as an attack to blockchain? If so, how easy is it to upload a virus into blockchain itself?
If you consider "congestion" an attack, then every transaction is attacking the network.