Application-layer firewalling: Raise your perimeter IQ Joel Snyder Opus One

Acknowledgements Products from Check Point, Cyberguard, NetScreen, Nortel Networks, Symantec, Secure Computing, Watchguard Support from Andy Briney, Neil Roiter at Information Security

Firewalls have been around for a very long time “[AT&T’s gateway creates] a sort of crunchy shell around a soft, chewy center.” (Bill Cheswick, Design of a Secure Internet Gateway, April, 1990) First firewalls deployed in Internet-connected organizations “Firewalls and Internet Security” published TIS toolkit commonly available Cisco buys PIX (Network Translation) CheckPoint revenues cross $100m WatchGuard introduces 1st FW appliance

Surely firewall makers have been busy since 1999 ? Clear market trends Faster Cheaper Smaller  New Guard: NetScreen (Juniper), Watchguard, SonicWALL  Old Guard: Cisco, Check Point Clear product trends Add VPN features  Site-to-site  Remote Access (?) Add policy-based URL control  Websense-type Add interfaces  No longer just inside, outside, DMZ

Shirley firewall makers have been busy since 1999 ? Clear market trends Faster Cheaper Smaller  New Guard: NetScreen (Juniper), Watchguard, SonicWALL  Old Guard: Cisco, Check Point Clear product trends Add VPN features  Site-to-site  Remote Access (?) Add policy-based URL control  Websense-type Add interfaces  No longer just inside, outside, DMZ

Incremental improvements are not very exciting Smaller, cheaper, faster: that’s great VPNs, more interfaces: that’s great But what have you done for me lately? To answer that, we need to digress to the oldest battle in all of firewall-dom: proxy versus packet filter!

Arguments between Proxy and Stateful PF continued Proxy More secure because you can look at application data stream More secure because you have independent TCP stacks Stateful PF Faster to write Faster to adapt Faster to run Faster also means cheaper

Proxy-based firewalls aren’t dead… just slow! Proxy Packet Filtering Src= Dst= TCP/IP Src= Dst= Kernel Inside network = /24 Outside net = RTL Process Space

Firewall Landscape: five years ago IBM eNetwork Secure Computing Altavista Firewall TIS Gauntlet Raptor Eagle Elron Cyberguard Ukiah Software NetGuard WatchGuard SonicWALL Check Point Livermore Software Milkyway Borderware Global Internet

Stateful Packet Filtering dominates the market Stateful Packet Filtering IP Kernel Check Point Cisco NetScreen SonicWALL Freeware-based products: Ipchains, IPF, Iptables, IPFW FW Newcomers: Fortinet, Toshiba, Ingate, Enterasys, many others

But… the core argument was never disputed Proxy-based firewalls do have the possibility to give you more control because they maintain application-layer state information The reality is that proxy-based firewalls rarely went very far down that path  Why? Market demand, obviously…

Firewall Evolution: What we hoped for… Additional granular controls on a wide variety of applications Intrusion detection and prevention functionality Vastly improved centralized management systems More flexible deployment options

Firewall Evolution: What we found… Additional granular controls on some a wide variety of applications Limited intrusion detection and prevention functionality Vastly improved centralized management systems More flexible deployment options Why? Market demand, obviously…

Additional Granular Controls focused on a few applications Everybody loves HTTP management  Header filtering  File type & MIME type blocking  Embedded Data blocking (Javascript)  Virus scanning, URL Filtering Other applications are piecemeal  FTP  SMTP  VoIP  File Sharing

HTTP-oriented features served “pressure points”

Advanced Controls are diverse across products Differentiating between “advanced” controls and “basic” controls was easy to do. Proxy-based firewalls proved to be almost undistinguishable from their “insecure” stateful packet filtering brethren. Vendors appear to be reactive, not proactive.

Virus Scans and Policy Controls are simple, right? No! Some firewalls insisted on having virus and/or URL scanning happen “off box” No! Some firewalls can’t configure where you scan for viruses No! Some devices don’t have virus scanning No! Some firewalls don’t support a local list of blocked URLs Conclusion: it’s not simple

We’ve learned how to write good GUIs, haven’t we? Not in the firewall business, we haven’t Additional granularity means additional thinking about resources Products are … disappointing The firewall people have a lot to learn from the SSL VPN people

Centralized management has improved a bit Folks who had it are doing slightly better than they were Folks who didn’t have it now generally have something We’re still missing a general policy management system for firewalls Many of the centralized management tools have very rough edges

“Intrusion” is the new buzzword in security Rate-based IPS technology In firewalls, means “SYN flood protection” May be smart (NS) May include shunning (SecComp, WG, CP) Content-based IPS technology Based on IDS-style thinking May have small signature base (NS, CP) May be an “IDS with the IPS bit on” (Symantec)

So what’s going on in the firewall business? Products are diverging, not converging Personalities of products are distinct IPS is a step forward, but not challenging the world of standalone products Rate of change of established products is slow compared to new entries

What does this mean for me and my firewall? Products are diverging Personalities are distinct IPS weaker than standalone Change rate slow Matching firewall to policy is hard; change in application or policy may mean changing product! Aggressive adoption of new features unlikely in popular products; need new blood to overcome product inertia

Application-layer firewalling Joel Snyder Opus One Member, Information Security Magazine test alliance

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