2 of 3 multisignature transaction vulnerability when one of the private keys is compromised I was wondering if and how multisignature wallets protect the owners from getting robbed. 

So in 2 of 3 multisignature scheme, if one of the owners' machines has been compromised (i.e. bad actor possesses the private key and can initiate a transaction without the actual owner knowing about it and the 2nd owner signs the transaction who assumes that transaction request was made by the legitimate owner), does multi-signature wallet protect users from this kind of scenario?

Does it even have a way to protect in this case? Is the assumption that wallet owners will be communicating about the transaction request offline?
does multi-signature wallet protect users from this kind of scenario?


Not necessarily. Ultimately it is dependent on the design of the application which is using multisig transactions.


  Does it even have a way to protect in this case? 


Assuming that the other 2 key holders will blindly sign once the primary key owner has sign, no. If the primary key is compromised, the transaction will be signed by either/both other parties.


  Is the assumption that wallet owners will be communicating about the transaction request offline?


In principle yes, the assumption is that the application requires signatories to decide to sign the transaction on their own accord. Sharing  partially signed transaction should be done in a secure private channel between signatories.