I have a question for the hive mind: what is the point of this, exactly?
I mean, I understand the attempt to gain access, and I understand why 2fa codes can be valuable to attempt to phish but that's like, not the thing here.
They just spam dozens to hundreds of these (I'm showing over 400 in my inbox right now) but like, even if I WANTED to give these codes to the attacker, I have no damn clue who the dude in China that's doing this is.
I'm confused as to what they hope to gain by trying over and over and over every couple of hours because it feels like there's no upside to whomever is running this bot, but I probably have missed a memo on some TTP around this, heh.
The thing that I have seen is while it looks like they are after MFA codes, those emails are a distraction from the actual account they are trying to take over, so be very careful when deleting the emails, there could be a legit email in there asking you to roll back an account change.
Dosen't Microsoft rate limit the attempts? In that case ypu can just select a random number, the trie to brute force it until the code send is the one selected.
It doesn't seem all that limited; I'll get 4-5 in a burst, then nothing for a couple of hours or a day or so, then 4-5 more, and so on.
Been ongoing for a couple of months now, and given it's a random 6 digit number, I don't think they're even remotely doing enough attempts to try to brute force it.
If Microsoft accepts, let's say, 3 attempts per code send, they already tried 1200 numbers (per your 400 emails), it's still short to the 10**6 random attempts on average (supposing that the codes are entirely random). If you email is part of a list of a thousand, they already had tried more that a million and got access to some of them.