Well you can’t necessarily, because who’s to say what various methods they’ve discovered. However, if we were to use the most famous recent example that relied

Well you can’t necessarily, because who’s to say what various methods they’ve discovered. However, if we were to use the most famous recent example that relied on an unknown sender transmitting a GIF containing the compromise, Signal does have some additional protection in that it doesn’t receive messages from unknown senders by default. Rather the recipient must accept the message explicitly.