ET HUNTING External SMB ANDX Request for Outlook Calendar Invite File (.ics) - Possible NTLM Hash Leak Attempt

alert smb $HOME_NET any -> $EXTERNAL_NET any (
    msg:"ET HUNTING External SMB ANDX Request for Outlook Calendar Invite File (.ics) - Possible NTLM Hash Leak Attempt";
    flow:established,to_server;
    content:"|ff|SMB"; depth:8;
    content:"|00 2E 00|i|00|c|00|s|00 00 00|"; nocase; fast_pattern; endswith;
    reference:url,www.varonis.com/blog/outlook-vulnerability-new-ways-to-leak-ntlm-hashes;
    reference:cve,2023-35636;
    classtype:credential-theft;
    sid:2050432; rev:1;
    metadata:affected_product Windows_11, attack_target Client_Endpoint, created_at 2024_01_24, cve CVE_2023_35636, deployment SSLDecrypt, performance_impact Low, confidence Low, signature_severity Major, updated_at 2024_01_24;
    target:src_ip;
)