alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET USER_AGENTS Suspicious User-Agent (MSIE)"; flow:established,to_server; http.user_agent; content:"MSIE|28|6.00.2900.5512|20 28|"; fast_pattern; content:"|3b 20|NT|28|"; distance:0; content:"|29 3b 20|AV|28|"; distance:0; content:"|29 3b 20|OV|28|"; distance:0; content:"|29 3b 20|NA|28|"; distance:0; content:"VR|28|PH"; reference:url,documents.trendmicro.com/assets/Tech-Brief-Tropic-Trooper-s-Back-USBferry-Attack-Targets-Air-gapped-Environments.pdf; classtype:trojan-activity; sid:2030170; rev:1; metadata:attack_target Client_Endpoint, created_at 2020_05_15, deployment Perimeter, performance_impact Low, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_05_15;)