Student's Linux daemon 0-day triggers InfoSec Institute outcry

Updated Controversy has accompanied the discovery by a student of a critical vulnerability in BackTrack, a flavour of Linux that's a favourite among security pros.

The previously undiscovered (hence zero-day) privilege escalation bug in the network penetration-testing distro was discovered during an ethical hacking class organised by the InfoSec Institute.

Jack Koziol, security programme manager at the institute, explained that the bug in Backtrack 5 R2 (the latest version) allowed the student to overwrite settings to gain a root shell. The flaw - which was not remotely exploitable - stemmed from a bug in wicd (the Wireless Interface Connection Daemon).

BackTrack Linux is a favourite among the security community, particularly penetration testers. The distro is normally booted off a CD or a USB stick and the bug would only be a worry if firms ran a network of machines using Backtrack AND the flaw was remotely exploitable. Neither is the case.

Other Linux distributions share the vulnerable wireless network card manager component, including Debian (details here) and Arch. An advisory and an (official) patched version of wicd 1.7.2, which fixes the issue, can be found here.

The InfoSec Institute initially described promoted the flaw as a "Backtrack 5 R2 priv escalation 0day" before revising its advisory to make it clear that the bug affected wicd (the Wireless Interface Connection Daemon), possibly in response to criticism from the BackTrack Linux community.

A commentary on the Infosec Institute advisory by the BackTrack Linux community, alongside a graphic depicting a bull taking a dump, is highly critical of the security training organisation handling of the bug.

Initially, the bug report confused us, as BackTrack 5 R2 by default has a single root user, with no open TCP or UDP ports – therefore a console escalation from root to root seemed frivolous. The title of the bug was even more confusing – calling it a “BackTrack 0day” misrepresents the bug, apparently in an attempt to make it seem bigger than it is.

As an organization who claim to be security professionals, the Infosec Institute should know better. They should know that an accurate vulnerability description is probably the most important aspect of a bug report. Without this basic rule in place, every single 3′rd party FTP overflow in windows would be categorized as a “Windows 0day”, and every PHP web application vulnerability would be defined as an “Apache 0day”.

The controversial security flaw was discovered during fuzzing, which is a technique that lobs random or unexpected data at software to trigger vulnerabilities. While it's unclear if it could be exploited remotely, it still needs fixing.

The security bug stems from a failure to sanitise user inputs, a deficiency that creates a mechanism to start a given executable or script with root-level privileges on systems running the daemon, provided the hacker has local hands-on access.

"This 0-day exploit for BackTrack 5 R2 was discovered by a student in the InfoSec Institute ethical hacking class, during an evening capture-the-flag exercise," Koziol explained. "The student wishes to remain anonymous, he has contributed a python version of the 0-day, a patch that can be applied to wicd, as well as a writeup detailing the discovery and exploitation process."

The cleverclogs who discovered the flaw enjoyed a breakfast of champions, Koziol explained.

"Usually the winner of the CTF exercise in the ethical hacking course gets a free InfoSec polo shirt, and the instructor buys him or her a beer. This guy was so excited he found the bug he stayed up all night making an exploit and patch and ended up having the beer for breakfast the day after while the rest of the class ate pancakes." ®

Bootnote

This story was revised throughout to reflect the BackTrack community's response to the InfoSec Institute's initial advisory and the educational institute's revision of its security bulletin.