alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"ET SHELLCODE Possible UTF-16 %u9090 NOP SLED"; flow:established,to_client; content:"%u9090%u"; nocase; pcre:"/^[a-f0-9]{4}/Ri"; reference:url,cansecwest.com/slides07/csw07-nazario.pdf; reference:url,www.sophos.com/security/technical-papers/malware_with_your_mocha.html; reference:url,www.windowsecurity.com/articles/Obfuscated-Shellcode-Part1.html; classtype:shellcode-detect; sid:2012111; rev:5; metadata:created_at 2010_12_28, confidence Medium, signature_severity Major, tag possible_exploitation, updated_at 2019_09_27;)