alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET INFO 404/Snake/Matiex Keylogger Style External IP Check"; flow:established,to_server; http.start; content:"GET / HTTP/1.1|0d 0a|User-Agent|3a 20|Mozilla/4.0 (compatible|3b 20|MSIE 6.0|3b 20|Windows NT 5.2|3b 20|.NET CLR1.0.3705|3b|)|0d 0a|Host|3a 20|checkip.dyndns.org|0d 0a|Connection|3a 20|Keep-Alive|0d 0a 0d 0a|"; bsize:151; fast_pattern; reference:md5,017e7b6b886cce51eb03ce097c1a4c80; classtype:external-ip-check; sid:2039190; rev:3; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2020_05_13, deployment Perimeter, malware_family 404Keylogger, confidence High, signature_severity Informational, updated_at 2023_05_24; target:src_ip;)