alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"ET WEB_CLIENT PDF Name Representation Obfuscation of Action"; flow:established,to_client; content:"|0d 0a 0d 0a|PDF-"; content:"/"; distance:0; content:!"Action"; within:6; content:"#"; within:16; pcre:"/\x2F(?!Action)(A|#41)(c|#63)(t|#74)(i|#69)(o|#6F)(n|#6E)/"; reference:url,blog.didierstevens.com/2008/04/29/pdf-let-me-count-the-ways/; classtype:bad-unknown; sid:2011529; rev:6; metadata:affected_product Web_Browsers, affected_product Web_Browser_Plugins, attack_target Client_Endpoint, created_at 2010_09_27, deployment Perimeter, signature_severity Major, tag Web_Client_Attacks, updated_at 2019_07_26;)