A device or email account is hacked

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.

Thx.
AXISHKAsked:
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masnrockCommented:
Wiping that device would by far make the most sense. Also consider installing some sort of protection on it. Lots of AV and anti malware solutions are available.

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Andrew LeniartIT Consultant & Freelance JournalistCommented:
Attached is a log captured in Exchange smtp log and our email filtering gateway log.
You forgot to attach the logs AXISHK.

That said, I would have to agree with masnrock's suggestion. Wiping the device back to factory defaults and then installing protection (VPN for WiFi in particular) would seem the best idea here. Mobile phones are very often infected or hacked because of users tendencies to have their phones set to automatically connect to unsecured free wifi hotspots without malware or wifi protection installed on the device.
kenfcampCommented:
The email headers could also prove useful, but I too agree with the above
JohnBusiness Consultant (Owner)Commented:
The hacker seem to come a.b.c.d.138, login to the Exchange through the user's credential
it seems that the hacker is still able to pass through.


I agree with the above. Wipe the device and set it up again.

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