A user email account seem to be hacked. Attached is a log captured in Exchange smtp log and our email filtering gateway log.
The client android device is SAMSUNG and its IP address is h.i.j.149.
The hacker seem to come a.b.c.d.138, login to the Exchange through the user's credential and send a ransome email to the user herself.
Can I send the email is sent from the user's Samsung device ? The time logged in gateway and Exchange is matched. However, the IP logged in filtering gateway and Exchange is difference. And I suppose if the Samsung device is hacked, the IP logged in filtering gateway should the Samsung device, which is h.i.j.149.
Actually, user has already changed the password before but it seems that the hacker is still able to pass through. I believe a device should be hacked and that's why I need to identify it.