From: SecuriTeam <support@securiteam.com.>
To: [email protected]
Date: 12 Jul 2007 16:46:12 +0200
Subject: [NT] IPSwitch WS_FTP Logging Server DoS
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IPSwitch WS_FTP Logging Server DoS
------------------------------------------------------------------------
SUMMARY
The WS FTP logging server is "a daemon that listens on UDP port 5151 and
is shipped with WS FTP and by default is turned on and used by the local
WS FTP instance. It binds to the public IP address of the server and is
accessible externally, in part so that other WS FTP machines are able to
use it as a logging interface". A vulnerability in IPSwitch's WS_FTP
Logging server allows remote attackers to cause the server to crash by
sending it a malformed request.
DETAILS
WS FTP uses a binary protocol to speak to the logging daemon, and each
transmission begins with a two byte header "0xab 0xaa". If using a long
string of characters to mangle the remaining portions of the message, a
pointer operation fails at:
0x00401769
cmp word ptr [ecx], 0AAADh
jnz short loc_401787
This crashes the process. By flipping two bytes immediately after the two
primary header bytes, you are also able to control where the dereferencing
address is at the time of the crash. However, this does not appear to
allow code execution on the remote host as the address referenced is too
far away from any user supplied input.
ADDITIONAL INFORMATION
The information has been provided by <mailto:jseitz@vdalabs.com.> Justin
Seitz of VDA Labs LLC.
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