WFTPD and WFTPD Pro 2.41 allows local users to cause a denial of service by executing the RENAME TO (RNTO) command before a RENAME FROM (RNFR) command.
source: wwwsecurityfocuscom/bid/1456/info
It is possible for a user to cause a denial of service against the WFtpd server Requesting an RNTO command without using the RNFR command first will cause the server service to stop responding A restart of the service is required to gain normal functionality
#!/usr/bin/perl
#
# WFTPD/WFTPD P ...