alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"ET INFO Adobe PDF in HTTP Flowbit Set"; flow:from_server,established; file_data; content:"%PDF-"; within:6; flowbits:set,ET.pdf.in.http; flowbits:noalert; reference:url,en.wikipedia.org/wiki/PDF; reference:url,en.wikipedia.org/wiki/List_of_file_signatures; reference:url,www.infosecinstitute.com/resources/hacking/pdf-file-format-basic-structure/; classtype:not-suspicious; sid:2015671; rev:11; metadata:affected_product Any, attack_target Client_Endpoint, tls_state plaintext, created_at 2010_09_25, deployment Perimeter, deployment Internal, deployment SSLDecrypt, performance_impact Low, confidence High, signature_severity Informational, tag File_Magic, updated_at 2025_01_30; target:src_ip;)