alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET USER_AGENTS Observed Malicious User-Agent (FastInvoice)"; flow:established,to_server; http.user_agent; content:"FastInvoice"; bsize:11; startswith; fast_pattern; reference:md5,42218b0ce7fc47f80aa239d4f9e000a1; classtype:bad-unknown; sid:2035932; rev:3; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2022_04_13, deployment Perimeter, deprecation_reason Age, confidence High, signature_severity Minor, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2024_12_02, reviewed_at 2024_12_02;)