Application-layer firewalling: Raise your perimeter IQ

Joel Snyder Opus One

Acknowledgements

http://infosecuritymag.techtarget.com/ • • 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 TIS toolkit commonly available “Firewalls and Internet Security” published Cisco buys PIX (Network Translation) CheckPoint revenues cross $100m WatchGuard introduces 1st FW appliance 1989 1991 1993 1995 1997 1999 2001 2003 2005

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 Process Space RTL

Inside network = 10.1.1.0/24

Src=10.1.1.99

Dst=5.6.7.8

TCP/IP Packet Filtering Kernel

Src=1.2.3.4

Dst=5.6.7.8

Outside net = 1.2.3.4

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 Check Point Cisco NetScreen SonicWALL

Freeware-based products: Ipchains, IPF, Iptables, IPFW FW Newcomers: Fortinet, Toshiba, Ingate, Enterasys, many others IP

Stateful Packet Filtering Kernel

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 • Vastly improved centralized management systems • Intrusion detection and prevention functionality • 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” CyberGuard Netscreen WatchGuard HTTP Action Controls

Post/Put/ Delete None Post

Filename & MIME type blocking Header Filtering

Filename; no MIME blocking Full Filename .EXE & .ZIP; no MIME blocking No MIME blocking Limited Set

SecureComputing

All

Symantec

Can block 'upload' only

Check Point

Get/Post/ Put/Head Filename & MIME type blocking Filename blocking by extension Full No Filename by wildcard; no MIME blocking Full

SOAP controls

Basic No No Block/Allow No Basic

URL Translation

Yes No No No No Yes

Can Block within HTTP…

ActiveX, Java, Javascript, VBScript, XML

Virus detection

Yes, external server ActiveX, Java ActiveX, Java, Cookies ActiveX, Java, Javascript, VBScript Yes, internal or external server None Local scanning, 2 types (signature/he uristic) WebDAV, DCOM Local scanning ActiveX, Java, Javascript, Vbscript Yes, external server

URL filtering/ blocking

WebSense WebSense plus local URL list WebBlocker Smartfilter and local URL list Rating system and local URL list OPSEC and local URL list

Advanced Controls are diverse across products Product CyberGuard Netscreen WatchGuard Secure Computing Symantec Check Point FTP H.323

• • • • • • • • • •

HTTP LDAP NNTP RealAudio

• • • • • • • • • • •

SIP SMTP POP DNS IMAP Socks

• • • • • • • • • • • • •

SNMP CIFS

• • • •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 devices don’t have virus scanning • No! Some firewalls can’t configure where you scan for viruses • No! Some firewalls don’t support a local list of blocked URLs

Conclusion: simple it’s not

We’ve learned how to write good GUIs, haven’t we?

• Not in the firewall business, we haven’t • Products are … disappointing • Additional granularity means additional thinking about resources

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 • Matching firewall to policy is hard; change in application or policy may mean changing product!

• • IPS weaker than standalone Change rate slow • 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 [email protected]

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