Concern over Bash vulnerability grows as exploit reported “in the wild” [Updated]

Dubbed "Shellshock," the vulnerability is already being exploited by what looks to be a web server botnet.

The vulnerability reported in the GNU Bourne Again Shell (Bash) yesterday, dubbed "Shellshock," may already have been exploited in the wild to take over Web servers as part of a botnet. More security experts are now weighing in on the severity of the bug, expressing fears that it could be used for an Internet "worm" to exploit large numbers of public Web servers. And the initial fix for the issue still left Bash vulnerable to attack, according to a new US CERT National Vulnerability Database entry. A second vulnerability in Bash allows for an attacker to overwrite files on the targeted system.

Update: The vulnerability was addressed by the maintainer of Bash, Chet Ramey,  in an email to the Open Source Software Security (oss-sec) mailing list. An unofficial patch that fixes the problem has  been developed, but there is as of yet no official patch that completely addresses both vulnerabilities.

In a blog post yesterday, Robert Graham of Errata Security noted that someone is already using a massive Internet scan to locate vulnerable servers for attack. In a brief scan, he found over 3,000 servers that were vulnerable "just on port 80"—the Internet Protocol port used for normal Web Hypertext Transfer Protocol (HTTP) requests. And his scan broke after a short period, meaning that there could be vast numbers of other servers vulnerable. A Google search by Ars using advanced search parameters yielded over two billion webpages that at least partially fit the profile for the Shellshock exploit.

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