ET WEB_SPECIFIC_APPS SonicWall Email Security Authenticated Directory Traversal in Branding Feature (CVE-2021-20023)

alert http any any -> $HOME_NET any (
    msg:"ET WEB_SPECIFIC_APPS SonicWall Email Security Authenticated Directory Traversal in Branding Feature (CVE-2021-20023)";
    flow:established,to_server;
    http.uri;
    content:"/dload_apps|3f|"; fast_pattern; startswith;
    content:"action|3d|";
    content:"path|3d|";
    pcre:"/^[^\x26]*?(?:(?:\x2e|%2[Ee]){1,2}(?:\x2f|\x5c|%5[Cc]|%2[Ff]){1,}){2,}/R";
    reference:url,cloud.google.com/blog/topics/threat-intelligence/zero-day-exploits-in-sonicwall-email-security-lead-to-compromise;
    reference:cve,2021-20023;
    classtype:web-application-attack;
    sid:2064936; rev:1;
    metadata:affected_product SonicWall, attack_target Server, tls_state TLSDecrypt, created_at 2025_09_26, cve CVE_2021_20023, deployment Perimeter, deployment Internal, deployment SSLDecrypt, confidence High, signature_severity Major, tag Exploit, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2025_09_26, mitre_tactic_id TA0001, mitre_tactic_name Initial_Access, mitre_technique_id T1190, mitre_technique_name Exploit_Public_Facing_Application;
    target:dest_ip;
)