Information Security News
by Sean Gallagher
A security vulnerability in the GNU Bourne Again Shell (Bash), the command-line shell used in many Linux and Unix operating systems, could leave systems running those operating systems open to exploitation by specially crafted attacks. “This issue is especially dangerous as there are many possible ways Bash can be called by an application,” a Red Hat security advisory warned.
The bug, discovered by Stephane Schazelas, is related to how Bash processes environmental variables passed by the operating system or by a program calling a Bash-based script. If Bash has been configured as the default system shell, it can be used by network–based attackers against servers and other Unix and Linux devices via Web requests, secure shell, telnet sessions, or other programs that use Bash to execute scripts.
Because of its wide distribution, the vulnerability could be as wide-ranging as the Heartbleed bug, though it may not be nearly as dangerous. The vulnerability affects versions 1.14 through 4.3 of GNU Bash. Patches have been issued by many of the major Linux distribution vendors for affected versions, including:
Over the past years, we became used to Microsoft Patches, the important, critical ones that would render your system fully vulnerable if you didn't apply them. We probably became so used that sometime we forget that our Linux servers also need patches.
Today I've learned about a criticalÂ Bash patch, that addresses the CVE-2014-6271. According the advisory:
"A flaw was found in the way Bash evaluated certain specially crafted environment variables. An attacker could use this flaw to override or bypass environment restrictions to execute shell commands. Certain services and applications allow remote unauthenticated attackers to provide environment variables, allowing them to exploit this issue."
The patches are already ready for most of the Linux distros, like RedHat and Debian, so waste no time.
Pedro Bueno (pbueno /%%/ isc. sans. org)