alert tcp $HOME_NET !80 -> $EXTERNAL_NET [!25,!445,!1500] (msg:"ET MALWARE Win32/BlackCarat XORed (0x77) CnC Checkin"; flow:established,to_server; dsize:>800; content:"|77 77|"; offset:2; depth:2; content:"|77|"; distance:1; within:1; content:"|77 77 77 77 77 77 77 77 77 77 77 77 77|"; distance:1; within:13; content:"|20 77 1e 77 19 77 13 77 18 77 00 77 04|"; distance:0; fast_pattern; content:!"|00 00 00 00 00 00|"; reference:md5,514AB639CD556CEBD78107B4A68A202A; reference:url,www.virusbulletin.com/uploads/pdf/conference_slides/2018/AncelKuprins-VB2018-WolfSheep.pdf; classtype:command-and-control; sid:2026525; rev:7; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2018_10_18, deployment Perimeter, malware_family BlackCarat, performance_impact Low, confidence High, signature_severity Major, tag RAT, updated_at 2019_07_26;)