####################################################################### Luigi Auriemma Application: Georgia SoftWorks SSH2 Server (GSW_SSHD) http://www.georgiasoftworks.com/prod_ssh2/ssh2_server.htm Versions: <= 7.01.0003 Platforms: Windows Bugs: A] format string in the log function B] buffer-overflow in the log function C] buffer-overflow in the handling of the password Exploitation: remote Date: 02 Jan 2008 Author: Luigi Auriemma e-mail: aluigi (at) autistici (dot) org [email concealed] web: aluigi.org ####################################################################### 1) Introduction 2) Bugs 3) The Code 4) Fix ####################################################################### =============== 1) Introduction =============== GSW_SSHD is a well known commercial SSH server which acts as SSH tunnel for the telnet server GS_Tnet.exe. ####################################################################### ======= 2) Bugs ======= ------------------------------------ A] format string in the log function ------------------------------------ The logging function used by the server is affected by a format string vulnerability caused by the usage of vsprintf for building the first message (like "LoginPassword(%s(%s)[%u])") and the usage of another vsprintf for building the final log entry. The bug can be exploitable through the username field. -------------------------------------- B] buffer-overflow in the log function -------------------------------------- A buffer-overflow vulnerability is located in the same logging function. It's enough to use an username longer than 10000 chars to exploit the vulnerability. -------------------------------------------------- C] buffer-overflow in the handling of the password -------------------------------------------------- The server is affected also by another buffer-overflow this time located in the instructions which handle the password supplied by the client exploitable through a string longer than 800 chars. ####################################################################### =========== 3) The Code =========== http://aluigi.org/poc/gswsshit.zip ####################################################################### ====== 4) Fix ====== No fix ####################################################################### --- Luigi Auriemma http://aluigi.org