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/br.ico"; fast_pattern; http.connection; bsize:5; content:"Close"; http.user_agent; bsize:108; content:"Mozilla/5.0|20|(iPhone|3b 20|CPU|20|iPhone|20|OS|20|12_0|20|like Mac|20|OS|20|X)|20|AppleWebKit/605.1.15|20|(KHTML,|20|like|20|Gecko)|20|Version/12.0"; http.header_names; to_lowercase; content:!"|0d 0a|referer|0d 0a|"; http.accept; bsize:7; content:"image/*"; reference:md5,efcf2797aaa1ff0bb8914aba8e3a5e15; reference:url,thedfirreport.com/2021/08/16/trickbot-leads-up-to-fake-1password-installation/; classtype:trojan-activity; sid:2033820; rev:5; metadata:attack_target Client_Endpoint, created_at 2021_08_27, deployment Perimeter, malware_family Cobalt_Strike, confidence Medium, signature_severity Major, updated_at 2024_05_04, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1001, mitre_technique_name Data_Obfuscation;)