alert http $EXTERNAL_NET any -> $HTTP_SERVERS any (msg:"ET WEB_SERVER Possible Perl Shell in HTTP POST"; flow:established,to_server; http.method; content:"POST"; nocase; http.request_body; content:"#!/bin/sh"; nocase; fast_pattern; reference:url,isc.sans.edu/diary.html?storyid=9478; classtype:web-application-attack; sid:2016642; rev:8; metadata:created_at 2013_03_22, confidence Medium, signature_severity Informational, updated_at 2020_09_18;)