############################################################## - S21Sec Advisory - ############################################################## Title: WzdFTPD Denial of Service ID: S21SEC-033-en Severity: Medium - Denial of Service History: 26.Dic.2006 Vulnerability discovered 8.Ene.2007 Vendor contacted Scope: FTP Server Denial of Service Platforms: Any Author: Jose Miguel Esparza (jesparza (at) s21sec (dot) com [email concealed]) URL: http://www.s21sec.com/avisos/s21sec-033-en.txt Release: Public [ SUMMARY ] WzdFTPD is a ftp server designed to be modular and portable, work under linux/win32/freebsd/openbsd, and to be entirely configurable online using SITE commands. It supports SSL, IPv6, multithreading, external scripts, and it uses Unix-like permissions and ACLs, with virtual users and groups. WzdFTPD project also supports bandwith limitation (per user, per group, or globally), group administrators, and per command authorization. [ AFFECTED VERSIONS ] Following versions are affected with this issue: - WzdFTPD v8.0 and prior. - Lastest version (8.1) is not affected by this vulnerability. [ DESCRIPTION ] It's possible to cause a denial of service sending a special crafted FTP command. [ WORKAROUND ] Add "key != NULL" condition in the chtbl_lookup function of the hash.c file until vendor solution or upgrade to 8.1. [ ACKNOWLEDGMENTS ] These vulnerabilities have been found and researched by: - Jose Miguel Esparza <jesparza (at) s21sec (dot) com [email concealed]> S21Sec With thanks to: - David Barroso <dbarroso (at) s21sec (dot) com [email concealed]> S21Sec [ REFERENCES ] * WzdFTPD http://www.wzdftpd.net/ * S21Sec http://www.s21sec.com