The most effective approach for an attacker would be to establish Tor routing and send packets to trigger a chain reaction across 3 or more relays.
Now, couldn’t these attacks potentially be an opportunity to introduce noise into the network to make it more challenging for an attacker attempting correlations? Given that these attacks will continue to exist in the future, why not make them beneficial to the network?
Certainly, this would require some adjustments in how relays handle or route packets to achieve the best possible anonymity and to prevent the attacker from varying their transmissions too abruptly, which could add metadata.
Another challenge might be that the attacker themselves would have access to the routing path. It could be useful to include at least one intermediate hop that the user doesn’t know, and that varies for each packet sent.
It’s a still highly theoretical idea I recently had, but I wanted to share it because I found it interesting.