DOS Attacks
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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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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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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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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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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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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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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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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