Snort up For Revamp, says Creator

A reader writes:"The creator of Snort, the open-source network-based Intrusion Detection System (IDS), says the software is up for an overhaul. Martin Roesch has told the AusCERT conference IDS has failed to impress the market, citing the inability of many to minimise the number of false alarms triggered by the monitoring devices. The next iteration will include "passive discovery" features."

Comments

Cool, but effective?

[Allen Zadr]

From the article:

"The idea is to take a policy like 'thou shalt not run OS X on the network,' and then if someone with a Mac plugs into our network... it can tell the firewall to [block them],"...

While this would be cool, the nature of TCP/IP says that it will be quickly defeated. There are already programs out there that will make your Linux box masquerade as another type of computer.

If a policy says, thou shalt not run P2P - then the P2P will be reached through proxy. If you use snort regular expression detection (one of the coolest features) then new protocols will be written to look like an innocuous service (P2P though ICMP/Ping).

The worst part, and my buddy Zero Hex could talk about this forever, is when ISPs start using this to enforce their will on users. Thou shalt not connect without Windows.

Basically, it's not likely to enforce policies among those who actively want to get around them. Instead, it will enforce policies that push an agenda.

Re:Cool, but effective?

[wfberg]

A GOOD firewall will be doing more then just blocking ports. It will analyze packets to determine the type of comunication being used. Which is not to say such things can't be circumvented, but it is much harder then just using a proxy.

Not quite. Case in point; try blocking instant messengers on your network. Turns out that if you block specific ports, you'll find that they start using port 80.

Ok, block any IM content on port 80, and they move to port 443, that's HTTPS, encrypted.

Ok, so you block some IM server hostnames (there are many) on your DNS server and block access to outside DNS and proxies. Then you find out that there are apps such as htthost/httport that will happily run on a box outside your network accepting encrypted traffic on the HTTPS port and with HTTPS headers, but that are actually proxies (similar things can be achieved on a linux box with a simple enough shellscript). This works easily enough to be downloaded by your smarter-than-average bear.

P2P programs could easily go the HTTPS route if blocking becomes enough of a nuisance. They went route 80 (HTTP port) a long while ago.

So what are your alternatives? Perhaps degrade network performance by interrupting (apparent) HTTPS sessions once in a while so that people won't be able to use certain applications? Or disallow any kind of encrypted communications?

Creative people will always find a way around it. You're better off dealing with those sorts of threats from the inside by dealing with the people rather than the technology. That's probably also true for outside hackers, script-kiddies and virusauthors, but those you typically don't know.

Re:Cool, but effective?

[Allen Zadr]

If you know of something that can block MSN Messenger effectively, let me know. It installs as part of windows, and without user intervention, tries very hard to bypass detection and get through to it's home servers.

I can have a policy - don't install this - don't use this, but most people do anyway just to make that damned message go away. "Wouldn't you like all the benefits of adding a .NET password to XP?". Sure, I can remove it, but the service packs put it back again. I turned it off through the registry, and a security update restored it. MSN Messenger is pervasive, and annoying. No user intervention necessary.

Back to "smart detection" -- After the first blocked attempt, it talks using standard http then as https (also over the correct ports). I don't want to block any web page that 'could' actually be a web page though.

the problem with IDSes

[Keruo]

the problem with IDS systems is encrypted traffic
if someone wants to attack your network, they can easily implement proxy which will encrypt all the traffic they transfer and thus disabling the IDS's ability to analyze the traffic