alert tcp $HOME_NET any -> $EXTERNAL_NET 443 (msg:"ET MALWARE Observed UltraVNC CnC Activity"; flow:established,to_server; dsize:12; content:"RFB 003.008|0a|"; depth:12; reference:md5,27741793672d8b69803f3d2434743731; reference:md5,076fd584d2fcdf5110f41bcbbd9f2c62; reference:md5,49749ee8fb2a2dab83494ab0e6cf5e7b; classtype:command-and-control; sid:2035893; rev:2; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2016_10_05, deployment Perimeter, malware_family UltraVNC, confidence Medium, signature_severity Major, tag c2, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2019_07_26, mitre_tactic_id TA0010, mitre_tactic_name Exfiltration, mitre_technique_id T1041, mitre_technique_name Exfiltration_Over_C2_Channel;)