Monitoring ASP.NET and SQL Server for Security

Question

What is the best (or any good) way to monitor an ASP.NET application to ensure that it is secure and to quickly detect intrusion? How do we know for sure that, as of right now, our application is entirely uncompromised?

We are about to launch an ASP.NET 4 web application, with the data stored on SQL Server. The web server runs in IIS on a Windows Server 2008 instance, and the database server runs on SQL Server 2008 on a separate Win 2008 instance.

We have reviewed Microsoft's security recommendations, and I think our application is very secure. We have implemented "defense in depth" and considered a range of attack vectors.

So we "feel" confident, but have no real visibility yet into the security of our system. How can we know immediately if someone has penetrated? How can we know if a package of some kind has been deposited on one of our servers? How can we know if a data leak is in progress?

What are some concepts, tools, best practices, etc.?

Thanks in advance, Brian

Additional Thoughts 4/22/11

Chris, thanks for the very helpful personal observations and tips below.

What is a good, comprehensive approach to monitoring current application activity for security? Beyond constant vigilance in applying best practices, patches, etc., I want to know exactly what is going on inside my system right now. I want to be able to observe and analyze its activity in a way that clearly shows me which traffic is suspect and which is not. Finally, I want this information to be totally accurate and easy to digest.

How do we efficiently get close to that? Wouldn't a good solution include monitoring logins, database activity, ASP.NET activity, etc. in addition to packets on the wire? What are some examples of how to assume a strong security posture?

Brian

Answer 1

The term you are looking for is Intrusion Detection System (IDS). There is a related term called Intrusion Prevention System (IPS).

IDS's monitor traffic coming into your servers at the IP level and will send alerts based on sophisticated analysis of the traffic.

IPS's are the next generation of IDS which actually attempt to block certain activities.

There are many commercial and open source systems available including Snort, SourceFire, Endace, and others.

In short, you should look at adding one of these systems to your mix for real time monitoring and potentially blocking of hazardous activities.

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I wanted to add a bit more information here as the comments area is just a bit small.

The main thing you need to understand are the types of attacks you will see. These are going to range from relatively unsophisticated automated scripts on up to highly sophisticated targeted attacks. They will also hit everything they can see from the web site itself to IIS, .Net, Mail server, SQL (if accessible), right down to your firewall and other exposed machines/services. A wholistic approach is the only way to really monitor what's going on.

Generally speaking, a new site/company is going to be hit with the automated scripts within a few minutes (I'd say 30 at most) of going live. Which is the number one reason new installations of MS Windows keep the network severely locked down during installation. Heck, I've seen machines nailed within 30 seconds of being turned on for the first time.

The approach hackers/worms take is to constantly scan wide ranges of IP addresses, this is followed up with machine fingerprinting for those that respond. Based on the profile they will send certain types of attacks your way. In some cases the profiling step is skipped and they attack certain ports regardless of response. Port 1443 (SQL) is a common one.

Although the most common form of attack, the automated ones are by far the easiest to deal with. Shutting down unused ports, turning off ICMP (ping response), and having a decent firewall in place will keep most of the scanners away.

For the scripted attacks, make sure you aren't exposing commonly installed packages like PhpMyAdmin, IIS's web admin tools, or even Remote Desktop outside of your firewall. Also, get rid of any accounts named "admin", "administrator", "guest", "sa", "dbo", etc Finally make sure your passwords AREN'T allowed to be someones name and are definitely NOT the default one that shipped with a product.

Along these lines make sure your database server is NOT directly accessible outside the firewall. If for some reason you have to have direct access then at the very least change the port # it responds to and enforce encryption.

Once all of this is properly done and secured the only services that are exposed should be the web ones (port 80 / 443). The items that can still be exploited are bugs in IIS, .Net, or your web application.

For IIS and .net you MUST install the windows updates from MS pretty much as soon as they are released. MS has been extremely good about pushing quality updates for windows, IIS, and .Net. Further a large majority of the updates are for vulnerabilities already being exploited in the wild. Our servers have been set to auto install updates as soon as they are available and we have never been burned on this (going back to at least when server 2003 was released).

Also you need to stay on top of the updates to your firewall. It wasn't that long ago that one of Cisco's firewalls had a bug where it could be overwhelmed. Unfortunately it let all traffic pass through when this happened. Although fixed pretty quickly, people were still being hammered over a year later because admins failed to keep up with the IOS patches. Same issue with windows updates. A lot of people have been hacked simply because they failed to apply updates that would have prevented it.

The more targeted attacks are a little harder to deal with. A fair number of hackers are going after custom web applications. Things like posting to contact us and login forms. The posts might include JavaScript that, once viewed by an administrator, could cause credentials to be transferred out or might lead to installing key loggers or Trojans on the recipients computers.

The problem here is that you could be compromised without even knowing it. Defenses include making sure HTML and JavaScript can't be submitted through your site; having rock solid (and constantly updated) spam and virus checks at the mail server, etc. Basically, you need to look at every possible way an external entity could send something to you and do something about it. A lot of Fortune 500 companies keep getting hit with things like this... Google included.

Hope the above helps someone. If so and it leads to a more secure environment then I'll be a happy guy. Unfortunately most companies don't monitor traffic so they have no idea just how much time is spent by their machines fending off this garbage.

Answer 2

I can say some thinks - but I will glad to hear more ideas.

How can we know immediately if someone has penetrated?

This is not so easy and in my opinion, ** an idea is to make some traps** inside your backoffice , together with monitor for double logins from different ips.

a trap can be anything you can think of, for example a non real page that say "create new administrator", or "change administrator password", on backoffice, and there anyone can gets in and try to make a new administrator is for sure a penetrator - of course this trap must be known only on you, or else there is no meaning for that.

For more security, any change to administrators must need a second password, and if some one try to make a real change on administrators account, or try to add any new administrator, and fails on this second password must be consider as a penetrator.

way to monitor an ASP.NET application

I think that any tool that monitor the pages for some text change, can help on that. For example this Network Monitor can monitor for specific text on you page and alert you, or take some actions if this text not found, that means some one change the page.

So you can add some special hiden text, and if you not found, then you can know for sure that some one change the core of your page, and probably is change files.

How can we know if a package of some kind has been deposited on one of our servers

This can be any aspx page loaded on your server and act like a file browser. For this not happens I suggest to add web.config files to the directories that used for uploading data, and on this web.config do not allow anything to run.

<configuration>
    <system.web>
      <authorization>
        <deny users="*" />
      </authorization>
    </system.web>
</configuration>

Answer 3

I have not tried it yet, but Lenny Zeltser directed me to OSSEC, which is a host-based intrusion detection system that continuously monitors an entire server to detect any suspicious activity. This looks like exactly what I want!

I will add more information once I have a chance to fully test it.

OSSEC can be found at http://www.ossec.net/