Anonymous FTP Should be considered a security concern and should be enabled only if it is absolutely necessary. Also, to allow FTP to work properly in a chroot environment, make sure that the file system containing the FTP home directory is not mounted as nosuid.
VULNERABILITIES IN UNIX
Information provided by the Sans Institute:
The ten most commonly exploited UNIX vulnerabilities?
Poor system administration practices
Flawed SUID programs (e.g., rdist, binmail)
HTTP servers and CGI application vulnerabilities
Default "+" entries in the /etc/hosts.equiv file
NFS/NIS vulverabilities sendmail program bugs
Buffer overruns (e.g., gets(), syslog())
SUID shell scripts