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TUCoPS :: Unix :: General :: ciach085.txt

INN News Servers Vulnerability


[ For Public Release ]

                       The U.S. Department of Energy
                    Computer Incident Advisory Capability
                           ___  __ __    _     ___
                          /       |     /_\   /
                          \___  __|__  /   \  \___

                             INFORMATION BULLETIN

                        INN News Server Vulnerabilities

July 22, 1997 20:00 GMT                                            Number H-85
PROBLEM:       A number of vulnerabilities have been identified in the INN
               News Server.
PLATFORM:      All platforms running of INN prior to version 1.6.
DAMAGE:        May allow remote individuals to obtain access to vulnerable
               systems.  However, post access is required to exploit these
SOLUTION:      Upgrade to INN version 1.6 immediately.
VULNERABILITY  Exploit details involving this vulnerability have been made
ASSESSMENT:    publicly available.

[ Start Secure Networks Inc. Advisory ]

Secure Networks Inc.
Security Advisory
July 21, 1997

INN news server vulnerabilities

This advisory addresses a number of vulnerabilities present in all versions of
INN prior to version 1.6.

Problem Description:

A number of vulnerabilities exist in all versions of INN prior to version 1.6
which allow remote individuals to obtain access to vulnerable systems. Post
access is required to exploit these vulnerabilities. However, due to the
method with which news is propagated, once a single server has been broken
into, all of its peers can be accessed.

Technical Details:

A number of string copies within the INN news server fail to check the size of
data they are copying. This results in buffer overflows in several locations,
allowing individuals to execute commands remotely, including spawning a shell
on the NNTP port.

An example of this situation is in the processing of the "From: " line by the
nnrpd process. In the ARTpost function in post.c, the From: line is copied
into a buffer on the stack without performing bounds checking:

ARTpost(article, idbuff)
    char                buff[NNTP_STRLEN + 2], frombuf[SMBUF];
    strcpy(frombuf, HDR(_from));

By crafting appropriate arguments in the From: header of the message, an
attacker can cause nnrpd to overwrite its stack, overwrite the function return
pointer on the stack, and thus execute arbitrary binary code.

Vulnerable Operating Systems and Software

All versions of INN prior to version 1.6 are vulnerable. To determine which
version of INN you are running, issue the following command on your news

% telnet localhost 119

Your NNTP server version string will be displayed. A typical output from a
vulnerable NNTP server would read:

Connected to localhost.
Escape character is '^]'.
200 InterNetNews NNRP server INN 1.5.1 17-Dec-1996 ready

A line reading:

telnet: Unable to connect to remote host: Connection refused

means that you are not running an NNTP server.

Fix Information

INN version 1.6 has been made availible at A fix
will not be made availible for prior releases and it is suggested that all
users running INN upgrade to version 1.6 immediately.

Please note that INN version 1.6 is currently in beta testing stages,
therefore new versions may appear at this location in the future.

Additional Information

Secure Networks Inc. wishes to thanks James Brister <> for his
assistance in this advisory and a resolution to these problems.

You can contact Secure Networks Inc. at <> using the following
PGP key:

Type Bits/KeyID    Date       User ID
pub  1024/9E55000D 1997/01/13 Secure Networks Inc. <>
                              Secure Networks <>

Version: 2.6.3ia


You can find past Secure Networks advisories at or at

You can browse our web site at

You can subscribe to our security advisory mailing list by sending mail to with the line "subscribe sni-advisories"

Copyright Notice

The contents of this advisory are Copyright (C) 1997 Secure Networks Inc, and
may be distributed freely provided that no fee is charged for distribution,
and that proper credit is given.

[ End Secure Networks Inc. Advisory ]

CIAC wishes to acknowledge the contributions of Secure Networks Inc. for the
information contained in this bulletin.

CIAC, the Computer Incident Advisory Capability, is the computer
security incident response team for the U.S. Department of Energy
(DOE) and the emergency backup response team for the National
Institutes of Health (NIH). CIAC is located at the Lawrence Livermore
National Laboratory in Livermore, California. CIAC is also a founding
member of FIRST, the Forum of Incident Response and Security Teams, a
global organization established to foster cooperation and coordination
among computer security teams worldwide.

CIAC services are available to DOE, DOE contractors, and the NIH. CIAC
can be contacted at:
    Voice:    +1 510-422-8193
    FAX:      +1 510-423-8002
    STU-III:  +1 510-423-2604

For emergencies and off-hour assistance, DOE, DOE contractor sites,
and the NIH may contact CIAC 24-hours a day. During off hours (5PM -
8AM PST), call the CIAC voice number 510-422-8193 and leave a message,
or call 800-759-7243 (800-SKY-PAGE) to send a Sky Page. CIAC has two
Sky Page PIN numbers, the primary PIN number, 8550070, is for the CIAC
duty person, and the secondary PIN number, 8550074 is for the CIAC
Project Leader.

Previous CIAC notices, anti-virus software, and other information are
available from the CIAC Computer Security Archive.

   World Wide Web:
   Anonymous FTP: (
   Modem access:        +1 (510) 423-4753 (28.8K baud)
                        +1 (510) 423-3331 (28.8K baud)

CIAC has several self-subscribing mailing lists for electronic
1. CIAC-BULLETIN for Advisories, highest priority - time critical
   information and Bulletins, important computer security information;
2. CIAC-NOTES for Notes, a collection of computer security articles;
3. SPI-ANNOUNCE for official news about Security Profile Inspector
   (SPI) software updates, new features, distribution and
4. SPI-NOTES, for discussion of problems and solutions regarding the
   use of SPI products.

Our mailing lists are managed by a public domain software package
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E-mail to or
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  e.g., subscribe ciac-notes

You will receive an acknowledgment email immediately with a confirmation
that you will need to mail back to the addresses above, as per the
instructions in the email.  This is a partial protection to make sure
you are really the one who asked to be signed up for the list in question.

If you include the word 'help' in the body of an email to the above address,
it will also send back an information file on how to subscribe/unsubscribe,
get past issues of CIAC bulletins via email, etc.

PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing
communities receive CIAC bulletins.  If you are not part of these
communities, please contact your agency's response team to report
incidents. Your agency's team will coordinate with CIAC. The Forum of
Incident Response and Security Teams (FIRST) is a world-wide
organization. A list of FIRST member organizations and their
constituencies can be obtained via WWW at

This document was prepared as an account of work sponsored by an
agency of the United States Government. Neither the United States
Government nor the University of California nor any of their
employees, makes any warranty, express or implied, or assumes any
legal liability or responsibility for the accuracy, completeness, or
usefulness of any information, apparatus, product, or process
disclosed, or represents that its use would not infringe privately
owned rights. Reference herein to any specific commercial products,
process, or service by trade name, trademark, manufacturer, or
otherwise, does not necessarily constitute or imply its endorsement,
recommendation or favoring by the United States Government or the
University of California. The views and opinions of authors expressed
herein do not necessarily state or reflect those of the United States
Government or the University of California, and shall not be used for
advertising or product endorsement purposes.

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