ET MALWARE Possible Locky Ransomware Writing Encrypted File over - SMB and SMB-DS v1 ASCII

alert tcp $HOME_NET any -> $EXTERNAL_NET [445,139] (
    msg:"ET MALWARE Possible Locky Ransomware Writing Encrypted File over - SMB and SMB-DS v1 ASCII";
    flow:to_server,established;
    content:"|ff|SMB|a2|"; offset:4; depth:5;
    byte_test:1,!&,0x80,6,relative;
    content:".locky|00|"; nocase; distance:0; fast_pattern;
    classtype:trojan-activity;
    sid:2022638; rev:1;
    metadata:attack_target Client_Endpoint, created_at 2016_03_23, deployment Perimeter, confidence Medium, signature_severity Major, tag Ransomware, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2019_07_26, mitre_tactic_id TA0040, mitre_tactic_name Impact, mitre_technique_id T1486, mitre_technique_name Data_Encrypted_for_Impact;
)