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IT Security and Insecurity Portal |
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Interesting SQL Injection case |
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 Posted: Tue Sep 18, 2007 4:19 pm |
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| pabloski |
| Beginner |
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| Joined: Sep 14, 2007 |
| Posts: 3 |
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Hi to all, I'm new to this forum and I'm new to SQL Injection, too.
I'm studying SQL Injection and I have selected as target the famous ( mmm not so famous after all  ) blogging platform dBlog ( http://www.dblog.it if someone is interested )
Ok, I was thinking to bypass the login form, I have studied some papers and cheat sheets and it seems feasible. The blog platform in question is written in VbScript and uses Jet database ( .mdb ) as storage.
That said, I'm studying this piece of code
| Code: |
FUserID = Request.Form("UserID")
FPassword = Request.Form("Password")
If FUserID <> "" AND FPassword <> "" Then
SQLAutori = " SELECT [Nick], [UserID], [Password], [Admin] FROM [Autori] WHERE [UserID] = '"& ControlloSQLInjection(FUserID) &"' "
Set RSAutori = Server.CreateObject("ADODB.Recordset")
RSAutori.Open SQLAutori, Conn, 1, 3
If NOT RSAutori.EOF Then
RSAutori.MoveFirst
If RSAutori("Password") = getSHAPassword(FPassword) Then
Session("BLOGNick") = RSAutori("Nick")
Session.TimeOut = 60
If RSAutori("Admin") = True Then
Session("BLOGAdmin") = True
Else
Session("BLOGAdmin") = False
End If
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the login form accepts two fields, Password and UserID, then the script verifies they are not empty and execute a query against UserID.....finally it uses the recordset obtained to verify if SHA1(Password) == stored password hash
the function ControlloSQLInjection is an anti-SQL injection measure....it replaces the following characters
[ --> [[ & Chr(0)
] --> []]
[[ & Chr(0) --> [[]
' --> ''
% --> [%]
_ --> [_]
# --> [#]
as you can see the problem is the substitution ' -- ''
I have red something about UTF7 and encodings used to bypass this kind of filters, but frankly I haven't understood the whole point at all 
so how can I insert a SQL statement if I can't use ' to pass ascii strings to the script? |
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| Posted: Tue Sep 18, 2007 5:40 pm |
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| waraxe |
| Site admin |
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| Joined: May 11, 2004 |
| Posts: 2407 |
| Location: Estonia, Tartu |
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Most of the real world ASP/VBscript website scripts are secured against sql injection by using substitution " '-->'' "or just removing single quote. So if you can find universal "way in", then you can do lot's of damage. So what I think is, that this kind of single quote sanitize is actually effective anti-hacking measure and can't be evaded in most cases.
Still - programmers can be lazy or just stupid and trust integer parameters, using them in sql clause WITHOUT single quotes. In this case you can just walk in ...
About UTF-methods - i have tried some tricks against php/mysql and php/postgresql platforms and they can work in rare cases. But against most targets it will not help (my personal opinion though ... ). |
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| Posted: Tue Sep 18, 2007 7:04 pm |
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| pabloski |
| Beginner |
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| Joined: Sep 14, 2007 |
| Posts: 3 |
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thanks for the reply
as regards dBlog I have found some weak spots in the comment posting script, there are 3 queries that don't sanitize the input, I'll search here for some injection point to steal admin password  |
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| Posted: Wed Sep 19, 2007 1:24 pm |
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| waraxe |
| Site admin |
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| Joined: May 11, 2004 |
| Posts: 2407 |
| Location: Estonia, Tartu |
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Well, after you pointed out this software, I have done some research and found out something else than sql injection - it appears, that database file is exposed to web and can be downloaded directly. Success rate is ~ 20%, in most cases IIS webserver will refuse to serve mdb files. Still, there are hundreds websites, offering their database to anyone 
So i wrote little advisory about this case:
http://www.waraxe.us/advisory-52.html
And here is proof-of-concept screenshot:
http://www.hot.ee/http123/dblog_example.png
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www.waraxe.us Forum Index -> Sql injection
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