What Are Sql Injection Attacks And How To Prevent?
Jan 24, 2004
this is a question I put in the sql community in microsoft, but havent be answered in full
------------
I am using dynamic sql to do a query with differents 'order' sentences and/or 'where' sentences depending on a variable I pass to the sp
ex:
create proc ex
@orden varchar(100)
@criterio varchar(100)
as
declare consulta varchar(4000)
set consulta=N'select pais from paises where '+@criterio' order by '+@orden
------------
I'd like to know it it uses 2 sp in the cache, as I read, the main sp and the query inside the variable of the dynamic sql. if so, as I imagine, then I suppose I have to do the main sp without any 'if' sentence to be the same sp, and so taking it from the cache and not recompile the sp
now, I have various 'if' sentences in the main sp (the caller of the dynamic sql) but I plan to remove them and do the 'if' by program -it is in asp.net-, so I suppose it is better because in this way the main sp is took from the cache, supposing this uses the cache different that the dynamic sql in the variable
what do u think? does the dynamic sql use 2 caches? if so, u think it is better to try to do the main sp same in all uses (no 'if' statements)?
-----
They told me this coding is not good (dynamic sql) because it can give control to the user?
I ask, how does it give control to use? what ar sql injection attack and how to prevent them?
I use dynamis sql because I have 150 queries to do, and thought dynamic sql is good
is it true that dynamic sql have to be recompiled in each execution? I suppose so only if the sql variable is different, right?
can u help me?
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Apr 8, 2004
Hi,
On my site I have a simple textbox which is a keyword search, people type a keyword and then that looks in 3 colums of an SQL database and returns any matches
The code is basic i.e. SELECT * FROM Table WHERE Column1 LIKE %searcg%
There is no validation of what goes into the text box and I am worried about SQL injection, what can I do to minimize the risk
I have just tried the site and put in two single quotes as the search term, this crashed the script so I know I am vunerable.
Can anyone help, perhaps point me in the direction of furthur resources on the subject?
Thanks
Ben
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May 1, 2007
Hello, Our Security specialist, is running an audit on one of my systems. All pages pass except the login page. It keeps saying I am getting hit with a SQL injection attack. I filter out special characters, both on the Client Side validation and the server side.It is only the one page I have is failing, and I am beginning to wonder if it is producing false positives.Protected Sub btnLogin_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnLogin.Click If Not Page.IsValid Then
lblError.Text = "Page Invalid"
Exit Sub End If Dim strMesage As String = ""
If Not IsInputSanitized(strMesage) Then
lblError.Text = strMesage
Exit Sub End If If Not ValueIsValid(txtUserName.Value.Trim) Then
lblError.Text = Globals.Message_InvalidCharacters
Exit Sub End If Public Function IsInputSanitized(ByRef p_strReturnMessage As String) As Boolean Dim loop1 As Integer Dim arr1() As String Dim coll As NameValueCollection Dim regexp As String = "^([^<>" & Chr(34) & "\%;)(&+]*)$"
Dim reg As Regex = New Regex(regexp) coll = Request.Form arr1 = coll.AllKeys 'Start at 1 so you will skip over the __VIEWSTATE
For loop1 = 0 To UBound(arr1) 'Skip over the ASPNET-generated controls as they will give a false positive.
If Left(coll.AllKeys(loop1), 2) <> "__" Then If Not reg.IsMatch(Request(arr1(loop1))) Then
p_strReturnMessage = Globals.Message_InvalidCharacters
Return False End If End If Next loop1 'If it never hit false retrun true
p_strReturnMessage = "Success"
Return True End Function If Not ValueIsValid(txtPassword.Value.Trim) Then
lblError.Text = Globals.Message_InvalidCharacters
Exit Sub End If If Not ValidateUser(txtUserName.Value.Trim, txtPassword.Value.Trim) Then
lblError.Text = Globals.Message_LoginInvalid
End If End Sub Here are the other validation routines 'This is a check to make sure that the String Values Entered into the Database field 'are indeed valid and without characters that can be used in injection attacks
Function ValueIsValid(ByVal p_Input As String) As Boolean Dim strIn As String = p_Input Dim x As Integer Dim A As String Dim l_Return As Boolean = True For x = 1 To Len(strIn) A = Mid(strIn, x, 1) 'Check each character in the string individually
If InStr("<>+%|?;()", A) <> 0 Then 'If this is not a "Bad" character
l_Return = False 'tack it onto the output string
End If Next Return l_Return End Function
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Nov 6, 2006
I am taking a class where the professor really dislikes using parameterized queries because he considers them to be pointless. Despite the many points that I and a classmate bring up, the only thing he considers valid is using them to prevent SQL injection attacks. To prevent this, he replaces all single quotes with a pair of single quotes. I know this works for SQL server, but will fail in some others (for instance MySQL also allows '). Is there other possibilies such as the ' that need to be protected against?
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Mar 2, 2006
My site has come under attack from sql injections. I thought I hadthings handled by replacing all single quotes with two single quotes,akaReplace(inputString, "'", "''")Alas, clever hackers have still managed to find a way to drop columnsfrom some of my tables. Can anybody direct me towards a best practicedocument on preventing these attacks?Thank you thank you,Kevin
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May 10, 2007
Greetings all,
For entertainment purposes, I've been reading some articles on SQL Injection Attacks and there should be a cover charge to read these articles. (excuse the sarcasm)
Most defense is based on the use of stored procedures or read only settings on the tables.
I'm looking for practical opinions and possibly some code that would convince me personally that this is indeed a real threat.
Also, if possible, please post remedies that are solid and not open ended.
Thanks all,
Adamus
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Jan 21, 2007
I am building my first ASP.Net app from scratch and while working on the DAL I came across the problem of SQL Injection. I searched on the web and read different articles but I am still unsure about the answer. My question is should I add
db.AddInParameter(dbCommand, "AvatarImageID", DbType.Int32, avatarImageID);
Add in Parameters to my C# code to avoid SQL Injection. What is the best practice. I am unclear if the stored procedure already helps me avoid SQl Injection or if I need the add in parameters in the C# methods to make it work. I need some help. Thanks, Newbie
My C# update method in the DAL (still working on the code)
private static bool Update(AvatarImageInfo avatarImage)
{
//Invoke a SQL command and return true if the update was successful.
db.ExecuteNonQuery("syl_AvatarImageUpdate",
avatarImage.AvatarImageID,
avatarImage.DateAdded,
avatarImage.ImageName,
avatarImage.ImagePath,
avatarImage.IsApproved);
return true;
}
I am using stored procedures to access the data in the database.
My update stored proc
set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
GO
ALTER PROCEDURE [dbo].[syl_AvatarImageUpdate]
@AvatarImageID int,
@DateAdded datetime,
@ImageName nvarchar(64),
@ImagePath nvarchar(64),
@IsApproved bit
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;
BEGIN TRY
UPDATE [syl_AvatarImages]
SET
[DateAdded] = @DateAdded,
[ImageName] = @ImageName,
[ImagePath] = @ImagePath,
[IsApproved] = @IsApproved
WHERE [AvatarImageID] = @AvatarImageID
RETURN
END TRY
BEGIN CATCH
--Execute LogError SP
EXECUTE [dbo].[syl_LogError];
--Being in a Catch Block indicates failure.
--Force RETURN to -1 for consistency (other return values are generated, such as -6).
RETURN -1
END CATCH
END
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May 20, 2008
Hi All, I am new at this. I found using xsd with store procedure come really handy. However, I am afraid of SQl Injections. How can I tighten up my database's security??Thanks allKen
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Jul 31, 2015
In my database some of the store procedures getting the data from xml nodes.so I need to implement the validation to xml data for prevent sql injection.
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Mar 22, 2008
Dear guys
I'm developing a web site that subscribers will directly connect to sql express and send results of their desktop application to database.
So every body, including hackers can easily obtain a login. ofcourse I will restrict each login to execute only one stored procedure specially created for himself and do nothing else. (or anotherquery to verify validity of each user, instead of creating special stored procedures for each one)
But, I'm worried about frequency of running that stored procedure buy bad users. I can limit frequency of running stored procedure, but anyhow each time of such control also takes time. should I pay attention to such matter?
I also don't know what if a user tries to broute force server with incorrect user names and passwords repeatedly. does it lead to slowing down the server? again, should I pay attention to such matter?
does firewall help? does IP tarcking help? are these enough? if so, where can I find extra information?
In fact this problem persists even if I want to redirect user communications to web service instead of direct connection to data base or even using emails. Anyhow hackers can do the same thing but only some more complexity is added to my project. I found this article for IP tracking in web sites http://weblogs.asp.net/omarzabir/archive/2007/10/16/prevent-denial-of-service-dos-attacks-in-your-web-application.aspx . Is this enough?
I wish to know the way big networks do in real world.
Can any one please help me? Infact I'm not a professional in security. what ever kind of extra suggestions will be appreciated.
regards.
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Aug 16, 2006
Hello to everyone
I am running MS SQL 2005 Express I get per day 2-4 hackers attacks trying to login from €œsa€?
Some 37 calls times per second one of attack was continuing 4 days
Is there some setting into MS SQL 2005 to reduce that?
Can you recommend me good firewall for DDOS attacks?
Is it there some legal action that I can take to this people I have their IPs most are from US and Canada?
Thank you in advance
val
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Nov 29, 2007
Hi, I´m new on this forum, I just need help to solve or avoid better saying attacks to a SQL Server 2005 database. I ´ve had some intruders on my database, changing some data on 2 tables. the information there is too important. But i need to know how can i get all the remote address that make some masive updates on my DB. I´ve make some triggers to avoid that, but those peaoples have reach modify data. I think is some user on the same VPN.
Help me please what can i do to get the ip address.
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Nov 24, 2004
It is not uncommon for me to review the event logs of our SQL Server and notice that someone is attempting to figure out the password for one of the SQL user accounts.........especially the "sa" username. But lately our SQL server has to be rebooted to where it is starting to become a nightly thing.
Last night the SQL Server was bombarded with attempted failed connections for 2 hours before it finally gave a blank BSOD. The SQL Server in question is in mixed mode and is a shared server. Strictly using Windows Authentication mode is not an option for us. The server has "beefy" hardware and has all updates and patches.
Sometimes, when I log on the server and notice that an IP address is making such attacks on the server, I put up an IPSEC policy against that IP. But that is not a good solution for reasons I dont think need to be outlined here.
So my question is, what can I do to better protect our SQL Server from these types of attacks? My thought on these attacks is not different than a DDOS that eventually takes the server down.
I have already done TCP/IP Hardening but not sure what else to do.
Thank you all for your replies.
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Jul 4, 2006
This is my code:
CommandText = "SELECT * FROM Products"
If textboxStockID.Text.Length > 0 Then
CommandText = CommandText & " where [StockID] like '%" & textboxStockID.Text & "%'"
End If
Is this subject to the sql injection bug... if so, what changes do I need to make?
Canning
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Nov 25, 2007
What is the best way to avoid SQL injection?I know not to do stuff in Visual Basic such as...
Dim objCmd As New SqlCommand("SELECT * FROM mytable where id ='" & Request.QueryString("id") & '" , objConn)As it's best to use stored proceduresIs there any other problems you guys might have had happen to you or other possibilites for attackers that I should know about? Cheers
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Jun 5, 2008
I manage a VBSript/ASP/IIS/SQL website for a nonprofit, and our website has been hacked by SQL injections. I have changed the code on the website so it can't access the database, cleaned the database, backed up the database, but now need to find a way to tighten up the security so it won't happen again.
We're a non-profit- so the server is Windows 2000 Terminal SP4 (yeah, I know, it's old, bear with me).
I was using the following code to access the database from the website:
dbconn.open "DSN=cptigers;UID=sqlwebaccess;Password=password" (where cptigers is the name of the DSN connection with SQL server authentication).
So far, I've removed read permission in IIS on the include file that I use to open the database. I've changed the data source to use Windows NT authentication, and set the SQL login MDBCA/cptigers (this is the IIS login) to have public and db_denydatawriter roles.
But I'm not sure how to call this database connection in the code (how do you define the IIS user and password?), and not sure if this is sufficient to protect from future SQL injections.
Am I heading the right direction? Thanks, Amanda
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Jun 16, 2005
Hi All:I can't seem to get this thing work... When I type this in a textbox : '; exec master.dbo.sp_addsrvrolemember 'redice','sysadmin' -- , there's no respond, I mean, I check redice's role, but the System Administrators is not checked.Any idea about this?Thanks in advance.
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Jul 21, 2005
Hi All,
First explain the SQL Injection and how it working and second what is the Solution of SQL Injection..... ?
Thanx,
Shally
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Aug 14, 2004
Hi there !
Can anyone put some more lights on SQL Injection ? Is there anyway to get rid of it ? If yes then please let me know ?
With Thanks !
sqlboy
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Jan 30, 2006
Does anyone have any insight regarding SQL injection involving a table name t_jiaozhu? Is this a new hack script or old? I am having a hard time finding any clear details other than ways to stop injection from happening. This I know, what I am trying to figure out is what damaged may have been caused (worse case) and what would be a good plan of attack to figure out what steps suceeded/failed.
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Mar 25, 2008
I have a windows 2003 server with SQL Express 2005. The server has about 15 websites and uses ASP
Hackers somehow are creating NT Administrator Users on the server and then logging in with Terminal Services.
I ran thru SQL injection and tried to stop these attacks by stopping keywords in the SQL, but they still happen
Can anyone help, I really cant afford to pay for a security analyst so any advice would be nice.
How are these guys creating users?
thanks
Nick
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Mar 13, 2008
Hi there. I use MS Enterprise library to get access to my MSSQL database. All actions are performed by stored procedures. Should I check the input parameters for "bad" symbols such as ' or union words or the library do all this for me? Thanks.
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Nov 21, 2006
What is SQL Injection? Can any body explain it briefly?
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Jan 15, 2007
Am looking for SQL injection automation tool,can anybody suggest a tool which will be helpful.
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Jul 29, 2006
I want to inject a "where" criteria parametrically, but I can't get this to work:
CREATE PROCEDURE dbo.CopyTestCases
@Criteria varchar(255)
AS
declare @t table(NID int not null);
set transaction isolation level serializable;
begin tran;
insert into TestIT (Product,CatID,Category,Title)
output inserted.TestID into @t( NID)
select Product,CatID,Category,Title
from TestIT where @Criteria order by TestID;
commit;
GO
I get the message "An expression of non-boolean type specified in a context where a condition is expected". How do I fix this?
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Jan 24, 2008
I haven't been able to get a clear-cut answer on this so I decided to ask here.
I have developed a web application that is used as a front-end to many SQL reports using report viewer.
The authentication on the front end uses a stored procedure to match the login name and password.
However, many of my reports do NOT use stored procedures. They are just standard text queries.
Is this secure? I don't know much about SQL Injection. Could an attacker see
all of the data in the database?
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Apr 9, 2008
A new take on my question from yesterday:
Does RS do any checks for SQL Injection attacks or is that entirely up to the developer?
i.e. if I have a report that uses dynamic SQL and pass in parameters via the web service are these parameters checked in any way?
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Jun 18, 2006
Hi, i have a big question about SQL injections,Im deploying a web site, and im using strore procedures, the store procedures recives the query parameters and then execute the query, that i already defined in them.I pass the store procedure´s name and their parameters via a sql statement adding the parameters to the string chain. The string chain is something like this: string sql = ("EXEC sp_StoreProcedure1 ' " + param1 + " ' + ' " paramN" ' )i define the store procedure´s name and the parameters in the string, and then i send the string to execute.My questions are,is there some kind of potential issue or attack that it can happens if i made the queries in this way?? is my database secure of sql injections just beacuse the use of store procedures???thanks for ur answers! ill appreciate them a lot
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Jun 28, 2006
Alright, so I have a basic search function to look through a field in my database which is decided by a query string. <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:DatabaseConnectionString %>"
SelectCommand="SELECT * FROM [Employee] WHERE ([Responsibilities] LIKE '%' + @Responsibilities + '%')"> <SelectParameters> <asp:QueryStringParameter Name="Responsibilities" QueryStringField="q" Type="String" /> </SelectParameters> </asp:SqlDataSource> But, I'd really like to fix it using parameterized SQL queries, so that people aren't dropping my tables. >_>I've been lookin' around for some code on how to do this in C#.NET, and most of them seem to look like this: SqlConnection objConnection = new SqlConnection(_ConnectionString);objConnection.Open();SqlCommand objCommand = new SqlCommand( "SELECT * FROM User WHERE Name = @Name AND Password = @Password", objConnection);objCommand.Parameters.Add("@Name", NameTextBox.Text);objCommand.Parameters.Add("@Password", PasswordTextBox.Text);SqlDataReader objReader = objCommand.ExecuteReader(); My problem is that I don't know how really know how to go from my code to this code... I mean, would I throw the latter in my backend code and call what it returns as a string, would I entirely replace my Datasource and do soemthin' with the code? Any help, in the form of tutorials or just straight up tellin' me here, would be greatly appreciated.Thanks. =D
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Nov 10, 2006
Hi everyone,it is the first time i try to do the sql injection. and i got the problem for the following code. Dim strSQL as String = ""Dim objConnection as New oleDBConnection(getConnectionString("image check list"))strSQL = " insert into tblTest (id, text) value ( 1, @Text)"cmdSelect.Parameters.Add(New SQLParameter("@Text", "abc"))Dim objDataAdapter As New oleDBDataAdapter(strSQL, objConnection)Dim objDS As New DataSet()objDataAdapter = NothingobjDS = Nothingthe exception said i have problem in "cmdSelect".i am using SQlServer as the data store.http://aspnet101.com/aspnet101/tutorials.aspx?id=1 => this is the reference site i read.Anyone can help?thanks a lot!
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Jul 3, 2007
Hello,
I am building a website in ASP.net 2.0 and I want to protect my self from sql Injection.
I am half way there in that I have built my own class that I use to check any input to the Database from a textbox (or user input) for specific characters that cause trouble, such as the “ ‘ � or “;� it then converts them to my own code for example “ ’ � = |^| the same function will convert my “code� back to the original character which works great until I get to Gridviews and Forum View.
Does anyone know how I would access the class I created through the gridview and formview so that any info they display gets first translated through my class.
Or if that is not possible how I would set the grideview or formview to translate the “codes� for me.
If I am totally off track here and there is a much better way to do all this then I am all ears. Please keep in mind I will require the “bad� characters to be saved in some way shape or form.
Thanks
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Oct 25, 2007
I have become a big fan of the datasets in Visual Studio 2005. I usually create the SQL for each method in the table adapter; however, I am wondering if there is any 'built-in' functions in the C files for sql injection prevention? I have read that using stored procedures is a good method for prevention. Should I be using SP rather than SQL within my methods in the data table?
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Jan 2, 2008
One night over the last week someone successfully found a hole in a line of code in an ASP.NET website and was able to run an injection script against our database. I know, I know, stupid stupid stupid of us, but the breach was in an old app and an old database that we hadn't really taken a look at in a while, hence the one hole they found. This script from what I can tell was able to get a list of the databases on the server and attempted to iterate through all of them. The login they seized only had permissions for two db's so that's all they could access, but I'm still very scared about what they could have done with that login. I don't see any data loss, but they definitely dumped the contents of all tables, some of which contained some sensitive information. That information was encrypted but I'm not sure how much better that makes me feel.
So my questions
1) Since the user account they seized was the DBO on the database, what types of things might they have been able to do in the hour or so they were poking around other than run select statements. I know the account had update and delete permissions, although they didn't delete anything. My guess is they didn't want to tip us that they were in so they left the data intact.
2) How should we investigate the health of the DB and the server, to make sure they didn’t insert any scripts that are monitoring or reporting on data.
3) With DBO login access could they have messed with any system tables or settings?
4) Would DBO access allow them to read DB passwords? We’ve changed all of them already but I’m still concerned.
OK, so I’ll stop asking questions because obviously any help you can provide would be awesome.
Thanks so much.
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