Mon Jan 5, 1:00 PM ET
Paul Roberts, IDG News Service
Computer security researchers are again warning about a critical vulnerability
in the Linux (news - web sites) kernel that could be used by malicious hackers
to take control of systems using the popular open source operating system.
ISEC Security Research said Monday
that it found a critical vulnerability in code that is used to manage virtual
memory on Linux systems. The vulnerability affects versions of the Linux
kernel up to and including version 2.6 and would give low-level Linux users
total control over a Linux system.
ISEC, a noncommercial security research
group based in Poland, discovered the problem in kernel code for a component
called "mremap," according to a message posted by Paul Starzetz, an ISEC
member.
At the Core
The kernel is the core of the Linux
operating system and provides basic services for all other parts of the operating
system such as allocating processor time for the programs running on the
computer and managing the system's memory or storage.
Mremap provides functionality for managing
virtual memory and is used continuously by programs that have exhausted their
allocation of memory, or that have been allocated memory in excess of what
they need, according to Dave Wreski, chief executive officer of secure Linux
vendor Guardian Digital.
Attackers could use the vulnerability
to create an invalid virtual memory area, which could destabilize the Linux
operating system or allow a malicious user to run attack code on the system.
Attackers would need local user access to the vulnerable machine, but would
not need any special privileges on the Linux system to exploit the hole,
ISEC said.
Researchers at ISEC said they have
developed test code to exploit the mremap vulnerability.
However, taking advantage of the hole
will be more difficult for outsiders, who will need to get user access to
the machine they want to compromise and then work backwards from the Linux
kernel patches to spot the flaw and write code to exploit it, Wreski said.
Similar Story
The warning follows news in December
of another critical flaw in version 2.4 of the Linux kernel. Malicious hackers
used that vulnerability to attack servers belonging to The Debian Project,
which produces the noncommercial Debian Linux distribution.
Critical Linux kernel vulnerabilities
are rare and the disclosure of two such holes within weeks of each other
is unprecedented, Wreski said.
The increase in the number of critical
flaws may be the result of more groups scrutinizing the security of the Linux
source code, he said.
ISEC did a good job of coordinating
with Linux vendors, working with them for a month prior to publishing information
on the mremap vulnerability, Wreski said.
Guardian Digital and Red Hat released
updated kernel packages on Monday to fix the mremap security hole. ISEC encouraged
Linux users to fix vulnerable systems as soon as software patches became
available from their vendor.