alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"ET SHELLCODE Unescape Variable %u Shellcode"; flow:established,to_client; content:"= unescape|28|"; nocase; content:"%u"; nocase; within:3; content:"%u"; nocase; within:6; pcre:"/var\x20[a-z,0-9]{1,30}\x20\x3D\x20unescape\x28.\x25u[a-f,0-9]{2,4}\x25u[a-f,0-9]{2,4}/i"; reference:url,www.symantec.com/avcenter/reference/evolving.shell.code.pdf; classtype:shellcode-detect; sid:2012534; rev:2; metadata:created_at 2011_03_22, confidence High, signature_severity Major, updated_at 2019_07_26;)