| Analisando um malware recebido por e-mail me deparei com um script VBA codificado, sendo assim busquei um script para decodificar e poder realizar a análise do mesmo, segue abaixo o script criado por Jean-Luc Antoine, podendo ser localizado em http://www.interclasse.com/scripts/decovbe.php | During a malware analisis i had to try to decrypt an VBA Script, so looking for on internet i found this script bellow. This script was written by Jean-Luc Antoine |
[sourcecode language="vb"]'===============================================================================
'===============================================================================
' SCRIPT........: scriptDecode.vbs
' VERSION.......: 1.5
' DATE..........: 11/22/2003
' AUTHOR........: Jean-Luc Antoine
' LINK..........: http://www.interclasse.com/scripts/decovbe.php
' ALTERED BY....: Joe Glessner
' DESCRIPTION...: Decodes scripts encoded with screnc.exe. Usable with
' Wscript by dragging an encoded script onto this one. If done
' this way, only the first 100 lines (or so) of the script
' will be displayed.
' If run using Cscript.exe the entire output will be
' displayed.
' This script can be used to output the decoded script to a
' file using Cscript.exe by calling it with the following
' syntax:
'
' cscript [Path]\scriptDecoder.vbs [Path]\<filename> >> output.txt
'
'===============================================================================
'===============================================================================
'**Start Encode**
'===============================================================================
'# START <CODE>
'===============================================================================
option explicit
'---------------------------------------------------------------------------
'# Declare variables
'---------------------------------------------------------------------------
Dim oArgs, NomFichier
'---------------------------------------------------------------------------
'# Check Arguments
'---------------------------------------------------------------------------
NomFichier=""
Set oArgs = WScript.Arguments
Select Case oArgs.Count
Case 0 'No Arg, popup a dialog box to choose the file
NomFichier=BrowseForFolder("Choose an encoded file", &H4031, &H0011)
Case 1
If Instr(oArgs(0),"?")=0 Then '-? ou /? => aide
NomFichier=oArgs(0)
End If
Case Else
WScript.Echo "Too many parameters"
End Select
Set oArgs = Nothing
'---------------------------------------------------------------------------
'# Decode the file and output the results
'---------------------------------------------------------------------------
If NomFichier<>"" Then
Dim fso
Set fso=WScript.CreateObject("Scripting.FileSystemObject")
If fso.FileExists(NomFichier) Then
Dim fic,contenu
Set fic = fso.OpenTextFile(NomFichier, 1)
Contenu=fic.readAll
fic.close
Set fic=Nothing
Const TagInit="#@~^" '#@~^awQAAA==
Const TagFin="==^#~@" '& chr(0)
Dim DebutCode, FinCode
Do
FinCode=0
DebutCode=Instr(Contenu,TagInit)
If DebutCode>0 Then
If (Instr(DebutCode,Contenu,"==")-DebutCode)=10 Then
'If "==" follows the tag
FinCode=Instr(DebutCode,Contenu,TagFin)
If FinCode>0 Then
Contenu=Left(Contenu,DebutCode-1) & _
Decode(Mid(Contenu,DebutCode+12,FinCode-DebutCode-12-6)) & _
Mid(Contenu,FinCode+6)
End If
End If
End If
Loop Until FinCode=0
WScript.Echo Contenu
Else
WScript.Echo Nomfichier & " not found"
End If
Set fso=Nothing
Else
WScript.Echo "Please give a filename"
WScript.Echo "Usage : " & wscript.fullname & " " & WScript.ScriptFullName & _
" <filename>"
End If
'===============================================================================
'# Functions
'===============================================================================
'---------------------------------------------------------------------------
'# Name................: Decode()
'# Use.................: Decode(Chaine)
'# Purpose.............: Reverse the encoding done by screnc.exe.
'---------------------------------------------------------------------------
Function Decode(Chaine)
Dim se,i,c,j,index,ChaineTemp
Dim tDecode(127)
Const Combinaison="1231232332321323132311233213233211323231311231321323112331123132"
Set se=WSCript.CreateObject("Scripting.Encoder")
For i=9 to 127
tDecode(i)="JLA"
Next
For i=9 to 127
ChaineTemp=Mid(se.EncodeScriptFile(".vbs",string(3,i),0,""),13,3)
For j=1 to 3
c=Asc(Mid(ChaineTemp,j,1))
tDecode(c)=Left(tDecode(c),j-1) & chr(i) & Mid(tDecode(c),j+1)
Next
Next
'Next line we correct a bug, otherwise a ")" could be decoded to a ">"
tDecode(42)=Left(tDecode(42),1) & ")" & Right(tDecode(42),1)
Set se=Nothing
Chaine=Replace(Replace(Chaine,"@&",chr(10)),"@#",chr(13))
Chaine=Replace(Replace(Chaine,"@*",">"),"@!","<")
Chaine=Replace(Chaine,"@$","@")
index=-1
For i=1 to Len(Chaine)
c=asc(Mid(Chaine,i,1))
If c<128 Then index=index+1
If (c=9) or ((c>31) and (c<128)) Then
If (c<>60) and (c<>62) and (c<>64) Then
Chaine=Left(Chaine,i-1) & Mid(tDecode(c),Mid(Combinaison, _
(index mod 64)+1,1),1) & Mid(Chaine,i+1)
End If
End If
Next
Decode=Chaine
End Function
'---------------------------------------------------------------------------
'# Name................: BrowseForFolder()
'# Use.................: BrowseForFolder(ByVal pstrPrompt, ByVal
'# pintBrowseType, ByVal pintLocation)
'# Purpose.............: Locate the encoded script using Shell.Application
'---------------------------------------------------------------------------
Function BrowseForFolder(ByVal pstrPrompt, ByVal pintBrowseType, ByVal pintLocation)
Dim ShellObject, pstrTempFolder, x
Set ShellObject=WScript.CreateObject("Shell.Application")
On Error Resume Next
Set pstrTempFolder=ShellObject.BrowseForFolder(&H0,pstrPrompt,pintBrowseType,pintLocation)
BrowseForFolder=pstrTempFolder.ParentFolder.ParseName(pstrTempFolder.Title).Path
If Err.Number<>0 Then BrowseForFolder=""
Set pstrTempFolder=Nothing
Set ShellObject=Nothing
End Function
'===============================================================================
'# END </CODE>
'===============================================================================
[/sourcecode]