alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"ET MALWARE [ESET] TA410 APT LookBack HTTP Server Response"; flow:established,to_client; http.stat_code; content:"200"; http.content_type; content:"image/gif"; bsize:9; http.header; pcre:"/^ETag\x3a\x20[0-9]{6}-[0-9]{3,5}-[0-9]{8}\r\n/m"; file.data; content:"|c2 2e ab 48|"; depth:4; fast_pattern; reference:url,www.welivesecurity.com/2022/04/27/lookback-ta410-umbrella-cyberespionage-ttps-activity/; reference:url,github.com/eset/malware-ioc/tree/master/ta410; classtype:trojan-activity; sid:2036413; rev:1; metadata:attack_target Client_Endpoint, created_at 2022_04_28, deployment Perimeter, malware_family TA410, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2022_04_28;)