alert ftp $EXTERNAL_NET any -> $HOME_NET any (msg:"GPL FTP CWD ~<CR><NEWLINE> attempt"; flow:to_server,established; content:"CWD "; content:" ~|0D 0A|"; reference:bugtraq,2601; reference:cve,2001-0421; classtype:denial-of-service; sid:2101728; rev:9; metadata:created_at 2010_09_23, cve CVE_2001_0421, signature_severity Unknown, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2019_07_26;)