Gaping hole in NAI's Gauntlet firewall
Another false sense of security gone
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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