[adamckay]

> the attacker obtained a valid administrative session token from _after_ any MFA would've been completed

But you can lock session tokens to specific IPs or user agents. I've implemented similar in the past for a B2B admin-panel, and whilst there were the occasional false positive with browsers updating in the middle of a session (incrementing the user agents version number) and people's IP changing if they switched networks (or in one instance, a badly configured office network that randomly routed through 2 proxy servers with different outbound IP addresses) which then made it demand MFA again, it was fairly rare and didn't attract too many complaints.