ET MALWARE ELF/RedXOR CnC Checkin

alert http [$HOME_NET,$HTTP_SERVERS] any -> $EXTERNAL_NET any (
    msg:"ET MALWARE ELF/RedXOR CnC Checkin";
    flow:established,to_server;
    pcre:"/^[\x20-\x7e\r\n]{0,13}[^\x20-\x7e\r\n]/Psi";
    http.method;
    content:"POST";
    http.content_len;
    content:"00000"; startswith;
    http.header;
    content:"Total-Length|3a 20|00000"; fast_pattern;
    reference:url,www.intezer.com/blog/malware-analysis/new-linux-backdoor-redxor-likely-operated-by-chinese-nation-state-actor/;
    classtype:command-and-control;
    sid:2031934; rev:1;
    metadata:affected_product Linux, attack_target Client_and_Server, created_at 2021_03_11, deployment Perimeter, malware_family RedXOR, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2021_03_11;
)