Security Basics mailing list archives
Re: Protocol Specific Intrusion Detect/Prevention Systems.
From: "Albert Gonzalez" <incodeblood () gmail com>
Date: Wed, 1 Mar 2006 15:52:21 -0600
Hello Davie, Comments in-line. On 2/27/06, coder <elite.coder () ntlworld com> wrote:
Hello Everyone, Some of you may have seen many of my emails on this list and the other lists, mainly asking about firewalls and filters.
[...snip...]
Anyways, I have been reading a book on Intrusion Detection and Prevention, which covers the limitations of IDSs and IPSs... and I think I have come up with a great idea to improve on these, and I just want to run it by people that are in the security field. It seems that current IDS/IPSs have several limitations... if they are signature based, you have to wait for new signatures for a new attack, if they are anomaly based they have to be trained to the network traffic, which takes a while and also they are generic in the sense that they have to detect attacks on all protocols/services.. which means lots of rules/signatures to process and the signatures are not very generic in the sense that a signature will only detect one type of attack.
Anymore limitations that you see, beyond these two that you state? You will be able to find limitations with ANYTHING you use, its just the nature of things. But you don't want to put all security tasks into one machine, it will get overwhelmed, especially the people that have to look at the data or make business decisions regarding the data.
My idea is to create a service specific IPS, which just monitors one services that it has been custom written for, so that it "fully understands" the service. So for example, the idea I have to the HTTP IPS will:
Well, since you said "service" then I guess SecureIIS can apply to this. Since SecureIIS protects the IIS service. Might be something to look into, You can download a free-trial of the software from Eeye's website. ModSecurity might also apply to this. Check that out too.
Search for and store the names of all the folders within the wwwrootfolder, then, when a 404 error is returned the IPS will check to see if the user was way off in folders, or just out of range.. eg: If the following folders were accessed that caused 404 errors were read from the IIS log file: \afolder\annotherfolder\index.html \afolder\annotherfolder\blah.html \afolder\index.html If these folders actually exist in the wwwroot, the IPS will just assume that the user mistyped the filename or they assumed a file/folder that didn't exist. BUT if these folders do not exist in the wwwroot folder, then the IPS will take it as a failed attack (after say 3 404s) and block the IP. The IPS will also store old folders that have been deleted (unless told not to, by the admin) for people that are linked to old pages that no longer exist for Google etc.
Damn, so attempting to view a folder, file, etc... is an attack attempt? And your IPS will block it? I can see you being paged quite often, that might cause blocking of legitimate traffic. That might fall into a different category of protection schemes, since well you know *most* (at least the ones I have used/tried) successful IPS in the industry *are* signature based and or a mix of the two (anomaly + signature). You get to inherit both limitations, YAY! :)
the IPS will scan for folders in the HTTP request that do not exist withinwwwroot (Traversal attempt etc)the IPS will also scan for SQL within a POST/GET (Possible SQL Injection) the IPS will scan for lots of characters that are the same and machinelanguage code (Possible buffer overflow) And other generic attacks can be scanned for, the other thing that all the service specific IPSs will scan for are:
To detect if an attacker has killed the IPS, the IPS will do an insertinto a remote DB (where it stores alerts etc) every X mins... if the admin page shows that an insert has not been made in X mins, the admin knows the IPS was killed and also the last IP to have sent data.
There HAS to more checks in here, you can' t assume just because there hasn't been an alert insert into the DB in X amount of time that the sensor is down. So many things can come into play, drop in packet volume, drop in alerts, connectivity issues with the network, etc.. So yea, a few checks need to be implemented before I see anyone deploying this. Also because the IPS stopped alerting doesn't mean it was killed by an attacker. Remember that most implementations of an IPS are inline.
I think the service specific intrusion detection scans that I have shown above can be applied to all services. Please let me know if this has been tried or if it is a good/bad idea. Thanks for your input.
You say you want "service" specific IPS, but at the end of the e-mail, still hard to see exactly what you are looking for, so you have to really ask yourself, what is it that you are proposing here? Hell, what do you want to SEE and PREVENT? Hope that helps, -Albert
~Davie Elliott
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Current thread:
- RE: Protocol Specific Intrusion Detect/Prevention Systems. Arun Vishwanathan (Mar 01)
- <Possible follow-ups>
- Re: Protocol Specific Intrusion Detect/Prevention Systems. Albert Gonzalez (Mar 02)
- Re: Protocol Specific Intrusion Detect/Prevention Systems. Rajeev Gupta (Mar 02)
- Re: Protocol Specific Intrusion Detect/Prevention Systems. Devdas Bhagat (Mar 03)
- Re: Protocol Specific Intrusion Detect/Prevention Systems. Gunnar Wolf (Mar 06)