alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET INFO vk .com API Usage Observed"; flow:established,to_server; http.method; content:"POST"; http.uri; content:"|2f|method|2f|messages|2e|send|3f|"; startswith; http.host; content:"api.vk.com"; bsize:10; fast_pattern; threshold:type limit, count 1, seconds 300, track by_src; classtype:misc-activity; sid:2050882; rev:2; metadata:attack_target Client_Endpoint, created_at 2024_02_15, deployment Perimeter, performance_impact Low, confidence High, signature_severity Informational, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2026_01_20;)