ET MALWARE Suspected PULSECHECK Webshell Access Inbound

alert http any any -> [$HOME_NET,$HTTP_SERVERS] any (
    msg:"ET MALWARE Suspected PULSECHECK Webshell Access Inbound";
    flow:established,to_server;
    http.method;
    content:"POST";
    http.header;
    content:"|0d 0a|x_cmd|3a 20|"; nocase; fast_pattern;
    pcre:"/^[\x20-\x7e\r\n]{0,13}[^\x20-\x7e\r\n]/R";
    http.header_names;
    content:"|0d 0a|x_key|0d 0a|"; nocase;
    content:"|0d 0a|x_cnt|0d 0a|"; nocase;
    content:"|0d 0a|x_cmd|0d 0a|"; nocase;
    reference:url,www.fireeye.com/blog/threat-research/2021/04/suspected-apt-actors-leverage-bypass-techniques-pulse-secure-zero-day.html;
    classtype:attempted-admin;
    sid:2032786; rev:3;
    metadata:attack_target Server, created_at 2021_04_20, deployment Perimeter, deployment Internal, deployment SSLDecrypt, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2021_05_05;
)