alert tcp $EXTERNAL_NET $HTTP_PORTS -> $HOME_NET any (msg:"ET WEB_CLIENT AVI RIFF Chunk Access Flowbit Set"; flow:established,to_client; flowbits:set,ET.AVI.RIFF.Chunk; content:"|52 49 46 46|"; content:"|41 56 49 20|"; distance:4; within:4; flowbits:noalert; classtype:not-suspicious; sid:2012142; rev:2; metadata:affected_product Web_Browsers, affected_product Web_Browser_Plugins, attack_target Client_Endpoint, created_at 2011_01_05, deployment Perimeter, signature_severity Major, tag Web_Client_Attacks, updated_at 2019_07_26;)