Penetration Testing HTML Posting Issue

Question

We are planning to go for a security testing certificate. For that reason we are using Paros tool to test our system. The system is written in GWT on front end and database connectivity is happening through Hibernate. When we use this tool to test our application following behaviour is happening which needs to be restricted.

The tool is able to see the data which is passed to server. This is fine but when we make any changes in the data through tool it gets updated in the system on database end. This is a big security issue.

Can someone guide me in this?

Answer 1

If you're still looking for a solution to this problem, you could use request signing. The reason I didn't mention it earlier was because the only time I had seen request signing, there were certificates involved, and it was mostly using the Web Services Security Standard. The other time I recommended implementation of request signing was for a mobile application - its relatively easier to do there also, since you can use certificates that are on the device to perform the signing, and the server can verify this signature (essentially, a public key encryption mechanism).

As you mention in the comments, there are multiple aspects to it - one is to prevent XSRF, which is essentially including a nonce to ensure that an attacker cannot replay requests, or craft requests that might harm an authenticated user. This nonce will have to come from the server, since anything that you create using Javascript, the attacker can create also. This nonce will make sure that your request is time specific, and that it cannot be replayed at a later point of time.

However, a nonce isn't going to stop attacks where a user is in a hostile network, and an attacker is performing a MitM attack on all traffic. The attacker can still modify a request, and since the server has never seen that nonce before, it will accept the request as valid. To prevent this, you need to countermeasures in place - one, all traffic should go via SSL, and two, all requests must be signed so as to prevent tampering. The signature part is particularly hard, especially if you have to ensure that an attacker cannot perform the same signing. The examples I have seen of it involve certificate level authentication for the webapp, and using these certificates to then perform the signing - which might be too stringent a requirement for the application that you seem to be developing. Other methodologies involve using something that the user has/knows - maybe a token, password, secret answer, etc. - that cannot be replicated by an attacker, and using that information to sign requests.

Here's an example on how you can do this via PHP. I don't know if this mechanism can be adapted to do it for your purposes, though. OAuth might be another possible method, but since I've never seen an application do it that way, I am not very sure.

Sorry I don't have a specific methodology or examples of code for you to look at, but most implementations I've seen are only from a design standpoint, versus an actual code standpoint.