.doc dropping NanoCore

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Files:
File name: BoA_ach_e.remit_notice_0313.doc
SHA256 ba01bcf05c68bf2ea9468550cf8405debbe6ef17757c11e0c162544941e39ddf
File size 594.0 KB ( 608256 bytes )

File name: jofb.exe
SHA256 4275e436de46df0103a63939e24f533f24c46f66c916b38700e49dbe463a9114
File size 423.5 KB ( 433664 bytes )

Download (password: malware)

URLs:
hxxp://www.elec-tb[.]com/tmp/jofb.exe
hxxp://cassb.ddns[.]net:5050

IPs:
185.112.35.3
178.239.21.201

Details:
This sample came attached to an email as a Bank of America themed macro'd .doc file "BoA_ach_e.remit_notice_0313.doc":
 

Upon enabling content, the macro immediately calls out to a payload site (my setup is not internet connected):
I downloaded the payload manually and took a look at the payload site:

It is an Iranian electrical product site that appears to have been around for awhile. Appears to be a compromised victim site.

I executed the payload while observing ProcessHacker. Process behavior was fairly quiet. As you can see in the ProcDOT graph below the malicious process copied itself into \Appdata\Local\ and modified several registry keys to lower internet security settings:
Poking around in memory strings made this malware fairly easy to identify, as it calls itself out (thank you, NanoCore!):
Another hallmark of NanoCore, strings that appear to be base64 encoded (I've never tried to decode these before. Perhaps another day.)

Taking a look at Wireshark we see C2 DNS callouts:
We can also observe traces of this site in process memory:
And the resolution of the site:

NanoCore is a prolific and fully featured RAT. Check out https://www.stratosphereips.org/blog/2018/9/7/what-do-we-know-about-nanocore-rat-a-review for more info.

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