alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE APT28/SkinnyBoy Checkin"; flow:established,to_server; http.method; content:"POST"; http.user_agent; content:"Opera"; bsize:5; http.request_body; content:"id="; startswith; content:"#"; distance:0; content:"#"; distance:0; content:"&current="; distance:0; fast_pattern; content:"&total="; distance:0; content:"&data="; distance:0; reference:url,cluster25.io/wp-content/uploads/2021/05/2021-05_FancyBear.pdf; classtype:command-and-control; sid:2033096; rev:2; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2021_06_04, deployment Perimeter, malware_family SkinnyBoy, performance_impact Low, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2021_06_11;)