alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"ET SHELLCODE Possible UTF-16 u9090 NOP SLED"; file_data; flow:established,to_client; content:"|5c|u9090|5c|"; 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:2017345; rev:4; metadata:created_at 2013_08_19, confidence Medium, signature_severity Major, tag possible_exploitation, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2019_07_26;)