alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Win32/Vermilion Stager Activity (GET)"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"/g.pixel"; bsize:8; fast_pattern; http.host; pcre:"/^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$/"; http.header_names; content:!"Referer"; content:"|0d 0a|Content-Type|0d 0a|Cookie|0d 0a|User-Agent|0d 0a|Host|0d 0a|Cache-Control|0d 0a 0d 0a|"; http.cookie; pcre:"/(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{4})$/"; reference:md5,6310a2c9f45fd46cd405e31eda2ad7d3; reference:url,www.intezer.com/blog/malware-analysis/vermilionstrike-reimplementation-cobaltstrike/; classtype:trojan-activity; sid:2033931; rev:1; metadata:created_at 2021_09_13, malware_family Win32_Vermilion, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2021_09_13;)