Gaping hole in NAI's Gauntlet firewall

[InfoSec News <isn () c4i org>]

http://www.theregister.co.uk/content/4/21471.html

By Kevin Poulsen
05/09/2001 

Experts are calling it a security manager's nightmare. For the second
time in as many years, a hole has been discovered in Network
Associate's Gauntlet firewall software that makes it possible for
intruders to turn the security system against the very networks it was
designed to protect, SecurityFocus has learned.

On Tuesday, the company's PGP Security division quietly released
patches for a buffer overflow vulnerability in the firewall's 'csmap'
SMTP proxy, a feature of the firewall that, ironically, is designed to
act as a protective membrane between an organization's mail server
application and the rest of the world.

In normal operation, csmap accepts mail connections from the Internet,
then forwards only valid traffic to the internal mail server.

By adding reams of text at a particular point in the mail transaction,
an attacker can overflow the memory dedicated to storing an email
address. Properly crafted computer instructions appended to the text
will then be executed by the machine, giving hackers a way in.

A spokesperson for Network Associates said the company could not
immediately comment Tuesday. The bug affects users of Gauntlet 5.0,
5.5 and 6.0 on Solaris and HP-UX, and the company's Web Shield line of
appliances.

The hole is the second serious security hole to be found in Gauntlet.
Last year, Network Associates' integration of Mattel's Cyber Patrol
filtering software into the product created another buffer overflow
vulnerability that potentially gave attackers remote 'root' level
access to the machine.

The new vulnerability, like the last, was discovered by Jim Stickley,
a San Diego-based computer security consultant with Garrison
Technologies. Stickley uncovered the hole in July while performing a
security audit for a Mississippi company that uses Gauntlet to protect
its internal network.

"Once you're on the firewall, you can go after any of the machines on
the network," Stickley says. "The firewall is just a conduit at that
point."

Unlike the earlier hole, the new one doesn't yield total control of
the compromised machine, says Stickley. But attackers have at their
disposal a variety of means of gaining 'root' access to a typical Unix
machine after penetrating at a lower level, says Stickley. With or
without 'root,' the internal network is accessible.

"Any time you hear of an exploit on the firewall that protects your
internal network from public access, its kind of worrisome," says Jeff
Haverlack, VP of information technology at a mid-sized financial
institution. (Haverlack spoke on condition that the institution not be
named). "If the Gauntlet is rendered useless through this exploit,
we've got our online banking server sitting out there unprotected."

But Haverlack still thinks well of Gauntlet, which commands a loyal
following for its application-level architecture. The VP notes that
buffer overflows are common in a variety of software products; A
buffer overflow bug in Microsoft's IIS web server allowed the Code Red
worm to spread around the world last July. "You're not going to be
able to advance without leaving some holes behind you," Haverlack
says.

But some experts find security holes in security software to be
particularly troubling.

"I think we should be expecting more," says Chris Wysopal, director of
research and development for security firm @Stake. A firewall is an
absolutely critical part of any corporate security. This is the thing
that keeps security professionals up at night.... Because unless
you've put in multiple layers of security, which is a good idea, it's
just opening the front door."

Stickley agrees. "These aren't supposed to happen. That's ridiculous,
that's amazing to me that they're letting these things go out the
door."

Network Associates had three percent of the $700 million firewall
market in 2000, according to IDC.

Gauntlet is not the only firewall to suffer security problems.
Industry leader Checkpoint has had four vulnerabilities reported this
year for its FireWall-1 product, though none of them yielded remote
access to the machine itself.

And last month Microsoft issued an advisory about its new ISA Server
firewall, warning that under certain circumstances an attacker can
slow down the system until it "deteriorate[s] to the point where it
would effectively disrupt all communications across the firewall."



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