alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE ESPecter Bootkit Initialization Activity (GET)"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"/Heart.aspx?ti="; startswith; fast_pattern; content:"&tn="; distance:0; content:"&tg="; distance:0; content:"&tv="; distance:0; http.header_names; content:!"Referer"; reference:url,www.welivesecurity.com/2021/10/05/uefi-threats-moving-esp-introducing-especter-bootkit/; classtype:trojan-activity; sid:2034145; rev:1; metadata:attack_target Client_Endpoint, created_at 2021_10_06, deployment Perimeter, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2021_10_06;)