Skip to main content

Few common web.xml misconfigurations-Part I

While doing code review usually I find various misconfigurations. I am trying to compile them here.
Although they might not be a comprehensive list and something I may miss, but will touch most of the common points: Refer-

1. Authentication & Authorization Bypass:


The above configuration shows how to setup web-based control. Here the assumption is that the everything in 'secure' directory must be accessible by 'admin' user only by using methods listed in tags i.e, GET and POST. No other methods should be allowed. But that is not the case!
In fact any HTTP method which is not explicitly enlisted here (HEAD,or any junk values like, JEFF,TEST etc) can be used to access the resources under 'secure' directory. It's also called HTTP verb tampering. Arshan Dabirsiaghi has a nice paper that summarizes this issue.
The solutions is just simply remove all above elements from above code and configuration will be properly applied to all requests.

2. Absence of Secure Flag: Sometimes some websites revert back to non-SSL connection or can be accessed over non-SSL connections (http://). This leaves the sessionID vulnerable to capturing which may lead to session hijacking. The sessionID must be marked with 'secure' flag.
In order to do that the following configuration can be defined in web.xml:


3. Customized Error pages are not defined: Sometimes the application faces unexpected error and is not able to handle it properly following which it displays it directly to the end user in form of stack traces or other signs. This may be a useful information for an adversary to launch attacks as it may reveal sensitive information about the code/platform/technology of the application and also tell about the application's input validation strategies. The developer should avoid these errors to be leaked to the end user. They should define some custom pages in the web.xml so that in case of error the applications should present a generic and customized page to the user instead of specific information-no matter what error occurs.
The following setting can be used:
Using the following configuration a nice error page will be displayed whenever the application responds with an HTTP 500 error. You can add additional entries for other HTTP status codes as well.



Great information.Great thoughts.It is very important to know all the people.It is great and happy to read this blogs.Thanks for making it.
Anonymous said…
Here is the original article published in Aug 2010. Plagiarism? Decide for yourself:

Popular posts from this blog

File Upload through Null Byte Injection

Sometimes, during file upload we come across situation wherein there would be check on the file extension at the client side as well as server side too. If the application does allow only .jpeg extension to be uploaded, the client side java script checks for the extension of the file before passing the request. We all know that how easily this can be defeated.
Some applications, checks for the extension at the server side also. That's not easy to bypass. However there are some ways with which it still can be bypassed. Most of server side scripts are written in high level languages such as Php, Java etc who still use some C/C++ libraries to read the file name and contents. That leads to the problem. In C/C++ a line ends with /00 or which is called Null Byte. So whenever the interpreter sees a null byte at the end of the a string, it stops reading thinking it has reached at the end of the string.
This can be used for the bypass. It works for many servers, specially php servers. Th…

SQL Injection in search field

Earlier I had written about performing SQL injection in search field and how to do a DoS attack and privilege escalation using 'Like' operators. Now another SQLi exploitation I came across recently. That too in the search field. This becomes important as lots of people don't pay much attention on the search forms/ fields in the application. My aim is to show that a search form can also be exploited with SQL Injection. The following queries are based on a real world exploitation. The steps and data are for just illustration purpose only. Suppose, the search form provides the details of users who have accessed the application some time and their login time details etc, we just need to provide their name in the search box provided. All the data were being going as Post request. So, to just fingerprint the database, I provide, 'nil'+'esh' in the search field and it successfully gives me the results. That means the database behind the application is concatenat…

Insecure protocols

Some basic insecure protocols and risk associated with them: