Flaws raise red flag on Linux security

A report earlier this week about a critical flaw in the Linux kernel was the latest in a series of recently discovered security problems with the popular open-source operating system.

A report earlier this week about a critical flaw in the Linux kernel was the latest in a series of recently discovered security problems with the popular open-source operating system.

But many users were unfazed by the report and say Linux remains a solid and secure environment for running enterprise applications.

Poland-based iSec Security Research this week said it had found a critical flaw in a function used to manage virtual memory on Linux systems. The flaw affects the 2.2, 2.4 and 2.6 versions of the Linux kernel, according to iSec.

The vulnerability could allow attackers to take administrative control of compromised systems and run attack code of their choice, an iSec advisory stated. ISec claimed that it had developed and successfully tested code that was capable of exploiting the flaw, although it added that actually launching such an attack wouldn't be easy.

The news follows the discovery of a similar flaw in the Linux 2.4 kernel last year. In November, unknown attackers used that flaw to take down several servers belonging to the Debian Project, which produces a noncommercial Linux distribution. And last month, an attack on the Gentoo Linux Project compromised a server that was being used to download copies of Gentoo's Linux source code by users.

The rise in such incidents can be attributed to Linux's growing popularity, which makes it a more attractive target for malicious attackers, says David Wreski, CEO of Linux security vendor Guardian Digital in Allendale, New Jersey.

"The underground hacker community is very interested in Linux as a potential target," he says. "Because of the accessibility of the source code to everyone, it provides an equal opportunity for malicious attackers to find vulnerabilities and ways to exploit them."

Even so, Linux remains a secure environment, says John Cahill, senior network security engineer at Piedmont Natural Gas in Charlotte, North Carolina.

"I would say it is more secure than Microsoft and other environments because the code is looked over by so many people and it's so widely available that any vulnerabilities can be quickly identified and patched," Cahill says. Piedmont uses Linux for several email-related functions and is considering its use for antispam purposes.

"There's not very much we've needed to do to secure Linux [applications]," says Joe Poole, manager for technical support at Boscov's Department Stores in Reading, Pennsylvania. The company runs several virtual Linux servers on its mainframes that are protected by network and internal firewalls. All nonessential services, such as file transfers and Telnet, have been disabled. But there has been no need for the kind of constant patching and maintenance required for Windows, Poole says.

Linux distributors in general are also doing a better job of shipping products that have nonessential services disabled by default, says Paul Schmel, adjunct information security officer at the University of Texas at Dallas.

"The biggest plus that Linux has is that it's designed to allow users to be users and not administrators," Schmel says. "What Linux has that Windows doesn't have is ease of configuration from an administrator's standpoint. Stopping and starting services, configuring services to only respond on certain ports and interfaces is dramatically easier than it is with Windows."