alert tcp-pkt any 445 -> $HOME_NET any (msg:"ET INFO NTLMv1 Session Setup Response - Challenge"; flow:established,to_client; content:"|2b 06 01 04 01 82 37 02 02 0a|"; content:"NTLMSSP|00 02 00 00 00|"; fast_pattern; threshold:type limit,count 1,seconds 300,track by_dst; classtype:misc-activity; sid:2067086; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, tls_state plaintext, created_at 2026_01_26, deployment Perimeter, deployment Internal, performance_impact Significant, confidence Medium, signature_severity Informational, updated_at 2026_01_26; target:dest_ip;)