alert tcp $EXTERNAL_NET $HTTP_PORTS -> $HOME_NET any (msg:"ET WEB_CLIENT Stealth attempt to execute Javascript code"; flow:from_server,established; pcre:"/(((URL|SRC|HREF|LOWSRC)[\s]*=)|(url[\s]*[\(]))[\s]*['"]*[\x09\x0a\x0b\x0c\x0d]*j[\x09\x0a\x0b\x0c\x0d]*a[\x09\x0a\x0b\x0c\x0d]*v[\x09\x0a\x0b\x0c\x0d]*a[\x09\x0a\x0b\x0c\x0d]*s[\x09\x0a\x0b\x0c\x0d]*c[\x09\x0a\x0b\x0c\x0d]*r[\x09\x0a\x0b\x0c\x0d]*i[\x09\x0a\x0b\x0c\x0d]*p[\x09\x0a\x0b\x0c\x0d]*t[\x09\x0a\x0b\x0c\x0d]*[\:]/i"; content:"="; content:!"javascript|3a|"; nocase; classtype:misc-attack; sid:2001101; rev:13; metadata:affected_product Web_Browsers, affected_product Web_Browser_Plugins, attack_target Client_Endpoint, created_at 2010_07_30, deployment Perimeter, signature_severity Major, tag Web_Client_Attacks, updated_at 2019_07_26;)