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Catch the security flaw #6

If you can find the security issue with this piece of code, write about it by adding a comment to this blog post. This is the scenario:- 1. There is a Web site that allows end users to upload their pictures. 2. On the Web server, the Web site is physically Read More...
Posted Friday, April 10, 2009 3:33 PM by Varun Sharma | 6 Comments

catch the security flaw #5 (flaw and its countermeasure)

In my last post , I showed input validation code that uses RegularExpressionValidators improperly. Thanks to Mathew Grabau and Marius Cristian CONSTANTIN for pointing out that the Page’s IsValid property has not been checked before using the input. As Read More...
Posted Monday, December 29, 2008 5:10 AM by Varun Sharma | 1 Comments

Catch the security flaw #5

A lot of web applications use RegularExpressionValidators for performing input validation [1]. Sometimes these validators are not implemented properly, which can lead to potential flaws. See if you can catch the flaw here:- Code for Default.aspx:- 1: Read More...
Posted Monday, December 22, 2008 4:57 AM by Varun Sharma | 5 Comments

Catch the Security Flaw(s) #4

Identify as many security issues as you can with this piece of code:- 1: [WebMethod] 2: public string GetEmpName( string empid) 3: { 4: SqlConnection con = new SqlConnection( "server=.;database=test;uid=sa;pwd=PassW2rd12" ); 5: SqlCommand cmd = new SqlCommand( Read More...
Posted Tuesday, December 02, 2008 2:18 PM by Varun Sharma | 4 Comments

Catch the Security Flaw #3

Quite a few web applications encrypt query string values. This is generally done as an added measure to prevent unauthorized access. Since the end user cannot chose a value and then encrypt it, changing parameters becomes difficult. But encryption is Read More...
Posted Monday, July 14, 2008 11:17 AM by Varun Sharma | 8 Comments

catch the security flaw #2 (flaw and its countermeasure)

In my previous “Catch the Security Flaw” post I wrote about a flawed CAPTCHA implementation. In this post I discuss what are the flaws in that implementation and how to prevent them. Before I go into the exact flaws, let us agree upon a standard notation Read More...
Posted Monday, June 16, 2008 11:04 AM by Varun Sharma | 1 Comments

Catch the security flaw #2

Consider a fictional web site that lets you create new accounts (as shown below). This site implements CAPTCHA to prevent a malicious user from creating large number of false accounts by running an automated script. The following code is used to implement Read More...
Posted Monday, March 31, 2008 6:49 PM by Varun Sharma | 7 Comments

Catch the security flaw #1 (Flaw and its countermeasure)

It is time to discuss the flawed code that I posted a couple of weeks back. The comments posted were good and in essence summarize the flaw. The circled part is an example of an embedded code block. The query string parameter “id” will be inserted inside Read More...
Posted Friday, February 08, 2008 6:44 PM by Varun Sharma | 1 Comments

Catch the security flaw #1

I will be from time to time, putting up flawed code as an open question on this blog. Those who can catch the flaw please do post about it in the comments section (preferably with the repro steps). After a few days, I will post the flaw and its countermeasure. Read More...
Posted Wednesday, January 23, 2008 11:47 AM by Varun Sharma | 4 Comments
 
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