alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Cobalt Strike Activity (GET)"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"/image-directory/na.png"; bsize:23; fast_pattern; http.connection; content:"Close"; bsize:5; http.user_agent; content:"Mozilla|2f|5|2e|0|20 28|Windows|20|NT|20|10|2e|0|3b 20|Win64|3b 20|x64|29 20|AppleWebKit|2f|537|2e|36|20 28|KHTML|2c 20|like|20|Gecko|29 20|Chrome|2f|42|2e|0|2e|2311|2e|135|20|Safari|2f|537|2e|36|20|Edge|2f|12|2e|246"; bsize:127; http.header_names; content:!"Referer"; reference:md5,544107beb5ab8c894253576d2cef1b0c; reference:url,malware-traffic-analysis.net/2022/07/25/index.html; classtype:trojan-activity; sid:2037830; rev:2; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2022_07_26, deployment Perimeter, deployment SSLDecrypt, deprecation_reason Age, malware_family Cobalt_Strike, confidence Medium, signature_severity Major, updated_at 2024_12_02, reviewed_at 2024_12_02, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1001, mitre_technique_name Data_Obfuscation;)