Over the past few days, Apple, Red Hat, and others have pushed out patches to vulnerabilities in the GNU Bourne Again Shell (bash). The vulnerabilities previously allowed attackers to execute commands remotely on systems that use the command parser under some conditions—including Web servers that use certain configurations of Apache. However, some of the patches made changes that broke from the functionality of the GNU bash code, so now debate continues about how to “un-fork” the patches and better secure bash.
At the same time, the urgency of applying those patches has mounted as more attacks that exploit the weaknesses in bash’s security (dubbed “Shellshock”) have appeared. In addition to the threat first spotted the day after the vulnerability was made public, a number of new attacks have emerged. While some appear to simply be vulnerability scans, there are also new exploit attempts that carry malware or attempt to give the attacker direct remote control of the targeted system.
On Monday, the SANS Technology Institute’s Internet Storm Center (ISC) elevated its INFOcon threat level—a measure of the danger level of current Internet “worms” and other threats based on Internet traffic—to Yellow. This level indicates an attack that poses a minor threat to the Internet’s infrastructure as a whole with potential significant impact on some systems. Johannes Ullrich, Dean of Research at SANS, noted that six exploits based on Shellshock have been recorded by the ISC’s servers and “honeypot” systems. (A honeypot is a virtual or physical computer system set up to entice attackers and record their actions.)