WU-FTPD S/KEY Authentication ftpd.c skey_challenge Function Remote Overflow
Critical Nessus Plugin ID 14372
SynopsisThe remote FTP server seems to be vulnerable to a remote buffer overflow.
DescriptionThis version of WU-FTPD contains a remote overflow if s/key support is enabled. The skey_challenge function fails to perform bounds checking on the name variable resulting in a buffer overflow. With a specially crafted request, an attacker can execute arbitrary code resulting in a loss of integrity and/or availability.
It appears that this vulnerability may be exploited prior to authentication.
It is reported that S/Key support is not enabled by default, though some operating system distributions which ship WU-FTPD may have it enabled.
*** Nessus solely relied on the banner of the remote server
*** to issue this warning, so it may be a false positive.
SolutionUpgrade to WU-FTPD 2.6.3 when available or disable SKEY or apply the patches available at http://www.wu-ftpd.org