WebApp Sec mailing list archives
RE: SQL Injection Basics
From: "Logan F.D. Greenlee" <lgreenlee () ciretose net>
Date: Mon, 10 Feb 2003 21:07:48 -0500
Robert is quite right. The best way to prevent SQL Injection attacks in ASP is to use a stored procedure and a Command object to call it. Specifically the syntax would look something like the following (it isn't tested): set conn=Server.CreateObject("ADODB.Connection") conn.ConnectionString = "Provider" set comm=Server.CreateObject("ADODB.Command") comm.CommandText="spTest" comm.CommandType=adCmdStoredProc set parameters = comm.Parameters parameters.Append comm.CreateParameter("@InputTestOne", adChar, adParamInput, 50) comm("@InputTestOne") = "TestOne" ' Some Result Set Operation here conn.close The Command object prevents in valid characters from entering the database. Clearly you must rely on the quality of the drivers that connect to the database. If the scrubbing and escaping is flawed in the Command object then the web application is at risk. Not only does this technique prevent invalid characters causing query failure and/or injection attacks, it helps performance of the web app and offloads complex processing tasks to the database server. Other benefits include enforcing character limits at the database, a second level of protection for people wishing to Break Things. This method is available in most mature web application/scripting environments. -Logan -----Original Message----- From: Keith Smith [mailto:ksmith () firesnacks com] Sent: Monday, February 10, 2003 8:12 PM To: rnilsen () catalystone com; 'Taco Fleur'; webappsec () securityfocus com Cc: 'Nick Jacobsen' Subject: RE: SQL Injection Basics Robert: In ASP, what is equivalent to a prepared statement... i.e. must one use for example a Stored Procedure in MS SQL Server, or is there some ASP code level means of doing so... e.g. Recordsets etc. Any good sources for information here? Keith -----Original Message----- From: Robert Nilsen [mailto:rnilsen () catalystone com] Sent: Monday February 10, 2003 6:08 PM To: Taco Fleur; webappsec () securityfocus com Cc: Nick Jacobsen Subject: RE: SQL Injection Basics I might be missing the point here (and surely it must have been posted/explained before), but in my world, the safest way to do SQL is through prepared statements, a.k.a. bind variables/paramenters whenever someone out in the client segment has "touched" the input. Rule number one must always be to never thrust the client! And being sloppy just once with validation could mean the end of your data = not putting focus on security! By using prepared statements, the code is safer AND, in most cases, the next run will execute quicker. -Robert -----Original Message----- From: Taco Fleur [mailto:tacofleur () nella net au] Sent: 10. februar 2003 23:31 To: webappsec () securityfocus com Cc: Nick Jacobsen Subject: Re: SQL Injection Basics SQL Injection works only when 1. SELECT * FROM foo WHERE foobar = $var 2. SELECT * FROM foo WHERE foobar = '$var' In number 1, if the variable is not checked for the type of integer people can submit for example /urlstring/index.cfm?var=1; AND NASTY CODE HERE In number 2, if the variable is not checked for tick marks, and does not escape any that are found /urlstring/index.cfm?var=blah' AND NASTY CODE HERE -- In ColdFusion ALL ticks submitted are escaped, I'm sure more languages out there do that. Anyway, what I am after is the backdoor, the Unicode equivalent... Anyone? I got this %25%32%37 from Davy, which makes sense but still does not work with ColdFusion The following is the result SELECT category FROM mytable WHERE (category = '%27') I am trying to find all possible ways for SQL Insertion so I can protect myself against it. Like I said I already convert any charters like ' () < > to its HTML equivalent, but I beleive there is a way to get around this with Unicode, but not sure... ----- Original Message ----- From: "Nick Jacobsen" <nick () ethicsdesign com> To: <dhurst () spidynamics com>; <webappsec () securityfocus com> Sent: Tuesday, February 11, 2003 7:37 AM Subject: Re: SQL Injection Basics
Right, I wasn't thinking too well... makes sense. Though, according
to
quite a few SQL injection faqs I have read, it said that you could
only
inject code if the developer used tick marks. However, I just
recently used
SQL injection on some code where the developer used NO tick marks, but injection still worked if the injection string contained TWO tick
marks.
Was this just a fluke, or is it something that the faqs had wrong? Nick J. nick () ethicsdesign com ----- Original Message ----- From: "Dennis Hurst" <dhurst () spidynamics com> To: "'Nick Jacobsen'" <nick () ethicsdesign com> Cc: <webappsec () securityfocus com> Sent: Monday, February 10, 2003 8:59 AM Subject: RE: SQL Injection BasicsNick, Good question, but SQL Injection is absolutely an issue in VBScript
(ASP
pages). Here's the deal, the ' only acts as a comment if it's in
the
source code, not when it's in a variable. So... If you have code that looks like this: Dim sSql, rs, oConnection '..... Setup the connection...... sSql = "Select * from myCustomers where FirstName = '" & Request("txtFirstName") & "'" Set rs = oConnection.Execute(sSql) '.....do something with the returned data..... And a user puts a ' in the text box called txtFirstName you end up
with
something that acts like this: Dim sSql, rs, oConnection '..... Setup the connection...... sSql = "Select * from myCustomers where FirstName = '''" Set rs = oConnection.Execute(sSql) '.....do something with the returned data..... Have a great day, Dennis Hurst dhurst () spidynamics com SPI Labs -----Original Message----- From: Nick Jacobsen [mailto:nick () ethicsdesign com] Sent: Monday, February 10, 2003 6:07 AM To: Loki; raul.johhut () hushmail com Cc: webappsec () securityfocus com Subject: Re: SQL Injection Basics Hmm... just a gues here, but if a developer is using VBScript as
the
scripting language, would SQL injection be impossible, since in
VBScript
the " ' " mark is a comment mark, and therefore never used in SQL statements? Nick J nick () ethicsdesign com ----- Original Message ----- From: "Loki" <loki () fatelabs com> To: <raul.johhut () hushmail com> Cc: <webappsec () securityfocus com> Sent: Saturday, February 08, 2003 9:16 PM Subject: Re: SQL Injection BasicsRaul: SQL injection is not replacing the userid field in the url with"sdfsd",its escaping an SQL query with a single tick (') that the
developer
doesn't escape (or in the case of PHP, GLOBALS is turned on in the php.ini). SQL injection is simply altering the SQL query sent to the SQL
server
and executing an a malicious query instead of what was expected by
the
developer. Depending on the remote server (Oracle, Microsoft SQL,MySQL,PostgreSQL), these statements will only differ based on their
stored
procedures. Microsoft SQL containing the more fun procedure of (xp_cmdshell) :) e.g. 'SELECT * FROM USERS Username: ' or 1=1-- There are several papers available on SQL injection attacks, one
in
particular written by Chris Anley at http://www.nextgenss.com/research/papers.html Typically, you can quickly check web apps for vulnerability toinjectionby just entering a single tick (') in the form submission field,hittingsubmit, and looking for any errors such as ODBC, etc. Loki Fate Research Labs www.fatelabs.com On Sat, 2003-02-08 at 20:21, raul.johhut () hushmail com wrote:I am pen testing a webapp and am having some problems with SQLinjection.The app creates an ODBC error. Is this a garuntee of SQL
Injection ?
If I use www.victim/test.asp?userid=sfdsd the error is "inncorrect syntax near line 28 of test.asp" (or
thats
the English translation equiv in my case).I know the database is called master, and has a table test. What
is
the syntax I should use ?What are the best freeware and open source tools for testing SQLinjection ? I tried WPosion which was OK.I also tried WebSleuth (which seems to have gone from GPL to
closed
source commercial btw). Am I right is saying that the SQL plugin has
to
connect directly to the database to work ? I can only see port 80 so don't think this will work ?Thanks, Raul. Concerned about your privacy? Follow this link to get FREE encrypted email: https://www.hushmail.com/?l=2 Big $$$ to be made with the HushMail Affiliate Program: https://www.hushmail.com/about.php?subloc=affiliate&l=427-- Loki <loki () fatelabs com>
Current thread:
- Re: SQL Injection Basics, (continued)
- Re: SQL Injection Basics Alex Russell (Feb 11)
- Re: SQL Injection Basics Jerry Connolly (Feb 11)
- Re: SQL Injection Basics dreamwvr () dreamwvr com (Feb 11)
- Re: SQL Injection Basics Jerry Connolly (Feb 11)
- Re: SQL Injection Basics Ken Anderson (Feb 11)
- WebSleuth and the SQLInjeciton Plugin Phil Cox (Mar 10)
- Re: WebSleuth and the SQLInjeciton Plugin Chip Andrews (Mar 10)
- Re: SQL Injection Basics Kevin Spett (Feb 11)
- RE: SQL Injection Basics Patrick Debois (Feb 11)
- Re: SQL Injection Basics Jim McGarvey (Feb 11)
- Re: SQL Injection Basics Mark Curphey (Feb 11)
- Re: SQL Injection Basics Jim McGarvey (Feb 12)
- Re: SQL Injection Basics dreamwvr () dreamwvr com (Feb 12)