ET HUNTING Microsoft Sharepoint Deserialization RCE via Workflow (CVE-2018-8421)

alert http any any -> $HOME_NET any (
    msg:"ET HUNTING Microsoft Sharepoint Deserialization RCE via Workflow (CVE-2018-8421)";
    flow:established,to_server;
    http.method;
    content:"POST";
    http.uri;
    content:"/_vti_bin/webpartpages.asmx";
    http.request_body;
    content:"|3c|ValidateWorkflowMarkupAndCreateSupportObjects"; fast_pattern;
    content:"|3c|workflowMarkupText|3e|";
    content:"|3c 21 5b|CDATA|5b|"; distance:0;
    reference:url,www.nccgroup.com/research-blog/technical-advisory-bypassing-microsoft-xoml-workflows-protection-mechanisms-using-deserialisation-of-untrusted-data/;
    reference:cve,2018-8421;
    classtype:web-application-attack;
    sid:2064136; rev:1;
    metadata:affected_product Microsoft_Sharepoint, attack_target Server, tls_state TLSDecrypt, created_at 2025_08_25, cve CVE_2018_8421, deployment Perimeter, deployment Internal, confidence High, signature_severity Major, tag Exploit, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2025_08_25, mitre_tactic_id TA0001, mitre_tactic_name Initial_Access, mitre_technique_id T1190, mitre_technique_name Exploit_Public_Facing_Application;
    target:dest_ip;
)