alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Bookworm CnC Beacon"; flow:to_server,established; http.request_line; content:"GET /0"; startswith; fast_pattern; http.uri; pcre:"/^\/0[a-f0-9]{48}$/i"; http.header_names; content:!"Accept"; content:!"Referer|0d 0a|"; content:!"User-Agent|0d 0a|"; reference:md5,8ae2468d3f208d07fb47ebb1e0e297d7; reference:url,researchcenter.paloaltonetworks.com/2015/11/bookworm-trojan-a-model-of-modular-architecture/; classtype:command-and-control; sid:2022073; rev:5; metadata:attack_target Client_Endpoint, created_at 2015_11_11, deployment Perimeter, performance_impact Significant, signature_severity Major, tag c2, updated_at 2024_04_29, mitre_tactic_id TA0010, mitre_tactic_name Exfiltration, mitre_technique_id T1041, mitre_technique_name Exfiltration_Over_C2_Channel;)