alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"ET RETIRED Possible LINE RUNNER Backdoor Connection Attempt"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"/+CSCOE+/portal.css?"; fast_pattern; startswith; content:"|3d|"; distance:0; content:"|26|"; distance:0; content:"|3d|"; distance:0; http.header_names; content:!"|0d 0a|Referer|0d 0a|"; reference:url,www.cyber.gc.ca/en/news-events/cyber-activity-impacting-cisco-asa-vpns; classtype:trojan-activity; sid:2052270; rev:2; metadata:affected_product Cisco_ASA, attack_target Networking_Equipment, tls_state TLSDecrypt, created_at 2024_04_25, deployment Perimeter, deployment SSLDecrypt, former_category MALWARE, malware_family LINE_RUNNER, performance_impact Low, confidence Low, signature_severity Major, updated_at 2024_10_04, reviewed_at 2024_10_04; target:dest_ip;)