That would take a computer forensic team. The most common issue I encounter is the password and logins are reused. For example many folk have they name or password the same across many sites.
There are many articles about that and why it's such a bad idea. One leak by a retailer or an infection on a PC that you have the browser remember passwords and it's game over.
Given the password reuse is most common I've found that to be the cause in about half the cases.
https://www.google.com/search?hl=en&as_q=&as_epq=HTTP+login+Detect+abnormal+logins+at finds priors on this but again you want to know what happened.
My bet is your PC was infected, you left your router setup to allow WiFi admin logins or you use the same name and/or password across many sites.
My Bank account just got hacked, and apparently it happened yesterday. It's registered that there were multiple purchases through Steam (a PC gaming platform), and that my Credit Card was used, and therefore assumed that either my Credit Card information was stolen or someone got into my Bank Account. So I checked my router (ASUS RT-AC87U) and found this in the logs:
Sep 4 11:59:59 ntp: start NTP update
Sep 4 12:01:01 HTTP login: Detect abnormal logins at 5 times. The newest one was from 207.172.85.203.
Sep 4 12:01:02 HTTP login: Detect abnormal logins at 10 times. The newest one was from 207.172.85.203.
Sep 4 12:01:02 HTTP login: Detect abnormal logins at 15 times. The newest one was from 207.172.85.203.
Sep 4 12:01:03 HTTP login: Detect abnormal logins at 20 times. The newest one was from 207.172.85.203.
Sep 4 12:01:03 HTTP login: Detect abnormal logins at 25 times. The newest one was from 207.172.85.203.
Sep 4 12:01:04 HTTP login: Detect abnormal logins at 30 times. The newest one was from 207.172.85.203.
Sep 4 12:01:04 HTTP login: Detect abnormal logins at 35 times. The newest one was from 207.172.85.203.
Sep 4 12:01:05 HTTP login: Detect abnormal logins at 40 times. The newest one was from 207.172.85.203.
Sep 4 12:01:05 HTTP login: Detect abnormal logins at 45 times. The newest one was from 207.172.85.203.
Sep 4 12:01:06 HTTP login: Detect abnormal logins at 50 times. The newest one was from 207.172.85.203.
And this message repeats over and over up to this:
Sep 4 12:05:55 HTTP login: Detect abnormal logins at 2845 times. The newest one was from 207.172.85.203.
Sep 4 12:05:55 HTTP login: Detect abnormal logins at 2850 times. The newest one was from 207.172.85.203.
Sep 4 12:35:37 miniupnpd[17490]: Expired NAT-PMP mapping port 57477 UDP removed
Sep 4 12:35:37 miniupnpd[17490]: Expired NAT-PMP mapping port 57477 TCP removed
Sep 4 13:00:01 ntp: start NTP update
The logs then continue with more commands like the
'Expired port' message, and some more updates. Can someone tell me what exactly happened, and what I should do from this point forward?
Thank you!
Side note: I myself have a Steam account, but my Computer with the Steam account logged in from was not on at the time that the Steam transaction happened, and my Steam Account receipt logs have no record of purchases happening within the last week.

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