alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MALWARE APT28 DealersChoice CnC Beacon Response"; flow:established,from_server; file_data; content:"k1="; within:3; fast_pattern; content:"&k2="; distance:0; content:"&k3="; distance:0; content:"&k4="; distance:0; pcre:"/&k3=\d+&k4=\d+$/"; reference:url,researchcenter.paloaltonetworks.com/2016/10/unit42-dealerschoice-sofacys-flash-player-exploit-platform/; classtype:targeted-activity; sid:2044216; rev:2; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2016_12_05, deployment Perimeter, malware_family APT28, confidence High, signature_severity Major, tag c2, updated_at 2023_02_16, former_sid 2823642, mitre_tactic_id TA0010, mitre_tactic_name Exfiltration, mitre_technique_id T1041, mitre_technique_name Exfiltration_Over_C2_Channel;)