alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"ET WEB_CLIENT PDF Name Representation Obfuscation of /Subtype"; flow:established,to_client; content:"|0d 0a 0d 0a|PDF-"; content:"/"; distance:0; content:!"Subtype"; within:7; content:"#"; within:19; pcre:"/\x2F(?!Subtype)(S|#53)(u|#75)(b|#62)(t|#74)(y|#79)(p|#70)(e|#65)/"; reference:url,blog.didierstevens.com/2008/04/29/pdf-let-me-count-the-ways/; classtype:bad-unknown; sid:2011528; rev:6; metadata:affected_product Web_Browsers, affected_product Web_Browser_Plugins, attack_target Client_Endpoint, created_at 2010_09_22, deployment Perimeter, signature_severity Major, tag Web_Client_Attacks, updated_at 2019_07_26;)