By Brian McWilliams 
In an attempt to show that personal firewalls may afford their users little protection 
against serious threats, a respected PC security expert has released a new software 
tool that pokes holes in many of the leading desktop security packages. 

Security-conscious Internet users, especially those on broadband connections, have 
made desktop firewall software into a booming business for companies like Symantec and 
Network Associates. But according to Steve Gibson, president of Gibson Research, 
almost all of these utilities only provide "pseudo protection" against attacks. That's 
because they put most of their effort into blocking incoming hacker attacks, while 
paying only scant attention to what he calls internal extrusion. 

"I really believe the problem of software in your computer misbehaving is much bigger 
than the problem of hacker attacks. Most people don't have any vulnerabilities; 
there's nothing a hacker can do to you. So I argue against the necessity of any kind 
of inbound blocking tool," said Gibson. 

To prove his point, Gibson has developed a free utility called LeakTest. The 27-Kbytes 
program is a trojan-horse/spyware simulator that attempts to slip past a personal 
firewall's defenses and connect to a server on the Internet. 

Not surprisingly, popular intrusion detection programs like BlackIce Defender from 
Network Ice fail to catch the outgoing connection and report it to the user. But more 
disturbingly, several firewalls that claim to offer outbound detection are also fooled 
by LeakTest. Among them, the best selling Norton Personal Firewall and McAfeeFirewall. 

Both are among a small number of desktop firewall programs that attempt to address the 
problem of unauthorized outbound leakage, but Gibson says they fall short and can be 
easily fooled or bypassed because they come pre-programmed to allow some applications 
to pass through the firewall. 

"This idea of allowing all these apps pre-approval is ludicrous. It's trivial to get 
permission out of the firewall without notifying the user," said Gibson, who observed 
that only one firewall, ZoneLab's ZoneAlarm, prevents malware from masquerading as a 
trusted program. 

"They do a cryptographic signature of the programs you're allowing. That's not hard to 
do, but they're the only ones who do it," he said. 

Tom Powledge, Symantec's product manager for Norton Internet Security, said the risks 
outlined by Gibson are low if users are running both a firewall and anti-virus 
software. And he said Symantec knows of no instances of programs that specifically 
target Norton Personal Firewall, which is shipped with NIS. 

But in response to Gibson's critique, Symantec plans to revise the application 
integrity checking feature in NIS, with an update available to users over Live Update 
by early next week. In the meantime, Powledge said concerned users can turn off 
automatic firewall rule creation. 

Judging by comments on the LeakTest message board at Gibson's site, plenty of users 
are concerned about the newly exposed porosity of their favorite firewall software. 
But Symantec's Powledge said their fears could have been avoided if Gibson had given 
vendors the customary advance notice before releasing LeakTest. 

"We were seeing no concern about this, and no exploits have been written. And while 
this makes customers aware of a potential issue, it also makes hackers aware," said 
Powledge. 

But Gibson, who had an earlier run-in with RealNetworks over the privacy behavior of 
its RealDownload product, said he's learned that unless pressure is brought to bear, 
companies are resistant to change. 

"These firewalls are not going to get better unless there's someone saying and able to 
prove -- and to enable the user to prove -- that these things are junk." 



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