Vulnerability Development mailing list archives
RE: Telnetd AYT overflow scanner and linux telnet 0.17
From: "Dawes, Rogan (ZA - Johannesburg)" <rdawes () deloitte co za>
Date: Tue, 31 Jul 2001 07:52:39 +0200
[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: aleph1 () securityfocus com [mailto:aleph1 () securityfocus com] Sent: 26 July 2001 11:21 To: bugtraq () securityfocus com Subject: Re: Telnetd AYT overflow scanner Summary of responses on this thread: From: Homer Wilson Smith <homer () lightlink com> 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 <rcrelia () cobaltgroup com> 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" <c3chu () alaska edu> Based on the results from the Telnet AYT scanner provided by info () secpoint com 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 <patchkov () ucalgary ca> 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 <gvb () abused com> Juniper Routers (running something based on one of the BSD's) are also vulnerable to this telnetd attack. From: bow <bow () bow net> 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 <stampolidis () city academic gr> 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" <leandro () funcitec rct-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" <imailtest () onlineok com> 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" <jts () deforest k12 wi us> 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 <je () sekure net> 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
Current thread:
- RE: Telnetd AYT overflow scanner and linux telnet 0.17 Dawes, Rogan (ZA - Johannesburg) (Jul 31)
- Re: Telnetd AYT overflow scanner and linux telnet 0.17 H D Moore (Jul 31)
- Re: Telnetd AYT overflow scanner and linux telnet 0.17 H D Moore (Jul 31)
- Re: Telnetd AYT overflow scanner and linux telnet 0.17 H D Moore (Jul 31)