alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET USER_AGENTS VPNFilter Related UA (curl53)"; flow:established,to_server; http.user_agent; content:"curl53"; depth:6; fast_pattern; endswith; reference:url,blog.talosintelligence.com/2018/09/vpnfilter-part-3.html; classtype:trojan-activity; sid:2026428; rev:4; metadata:affected_product Linux, attack_target Networking_Equipment, created_at 2018_10_01, deployment Perimeter, malware_family VPNFilter, confidence High, signature_severity Major, updated_at 2020_09_16;)