alert http $EXTERNAL_NET $HTTP_PORTS -> $HOME_NET any (msg:"ET SHELLCODE Possible Unescape %u Shellcode/Heap Spray"; flow:established,to_client; content:"unescape"; nocase; content:"%u"; nocase; distance:0; content:"%u"; nocase; within:6; pcre:"/unescape.+\x25u[0-9,a-f]{2,4}\x25u[0-9,a-f]{2,4}/smi"; reference:url,www.w3schools.com/jsref/jsref_unescape.asp; reference:url,isc.sans.org/diary.html?storyid=7906; reference:url,isc.sans.org/diary.html?storyid=7903; reference:url,malzilla.sourceforge.net/tutorial01/index.html; classtype:shellcode-detect; sid:2011346; rev:7; metadata:created_at 2010_09_28, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2019_07_26;)