__________________________________________________________
The U.S. Department of Energy
Computer Incident Advisory Capability
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INFORMATION BULLETIN
HP-UX Security Vulnerabilities (chfn, Remote Watch)
December 13, 1996 15:00 GMT Number H-16
______________________________________________________________________________
PROBLEM: Two problems have been identified in the HP-UX operating
system: 1) chfn buffer overrun, and 2) HP Remote Watch.
PLATFORM: 1) All platforms running HP-UX 9.x and 10.x, 2) HP 9000 series
300/400/700/800s running HP-UX 9.x.
DAMAGE: 1) chfn vulnerability may allow local users to gain root
privileges. 2) HP Remote Watch vulnerabilities may allow users
unauthorized root access.
SOLUTION: Apply the workarounds or solutions provided below.
______________________________________________________________________________
VULNERABILITY Exploit information involving these vulnerabilities have been
ASSESSMENT: made publicly available.
______________________________________________________________________________
[ Start AUSCERT Advisory ]
1. chfn Buffer Overrun Vulnerability
===========================================================================
AA-96.18 AUSCERT Advisory
HP-UX chfn Buffer Overrun Vulnerability
9 December 1996
Last Revised: --
----------------------------------------------------------------------------
AUSCERT has received information that a vulnerability exists in the
chfn(1) program under HP-UX 9.x and 10.x.
This vulnerability may allow local users to gain root privileges.
Exploit information involving this vulnerability has been made publicly
available.
Currently there are no vendor patches available that address this
vulnerability. AUSCERT recommends that sites take the steps outlined in
section 3 as soon as possible.
This advisory will be updated as more information becomes available.
----------------------------------------------------------------------------
1. Description
AUSCERT has received information that a vulnerability exists in the
HP-UX chfn(1) program. The chfn command is used to change user
information in the password file, and is installed by default.
Due to insufficient bounds checking on arguments which are supplied
by users, it is possible to overwrite the internal stack space of the
chfn program while it is executing. By supplying a carefully
designed argument to the chfn program, intruders may be able to
force chfn to execute arbitrary commands. As chfn is setuid
root, this may allow intruders to run arbitrary commands with root
privileges.
This vulnerability is known to affect both HP-UX 9.x and 10.x.
By default, chfn is located in /usr/bin under both HP-UX 9.x and 10.x.
Exploit information involving this vulnerability has been made
publicly available.
2. Impact
Local users may gain root privileges.
3. Workarounds/Solution
AUSCERT recommends that sites limit the possible exploitation of this
vulnerability by immediately removing the setuid permissions as stated
in Section 3.1. If the chfn command is required, AUSCERT recommends
the chfn wrapper program given in Section 3.2 be installed.
Currently there are no vendor patches available that address this
vulnerability. AUSCERT recommends that official vendor patches be
installed when they are made available.
3.1 Remove setuid and non-root execute permissions
To prevent the exploitation of the vulnerability described in the
advisory, AUSCERT recommends that the setuid permissions be removed
from the chfn program immediately. As the chfn program will no
longer work for non-root users, it is recommended that the execute
permissions also be removed. Before doing so, the original permissions
for chfn should be noted as they will be needed if sites choose to
install the chfn wrapper program (Section 3.2).
For example:
# ls -l /usr/bin/chfn
-r-sr-xr-x 1 root bin 20480 Jun 10 1996 /usr/bin/chfn
# chmod 500 /usr/bin/chfn
# ls -l /usr/bin/chfn
-r-x------ 1 root bin 20480 Jun 10 1996 /usr/bin/chfn
Note that this will remove the ability for any non-root user to run the
chfn program.
3.2 Install chfn wrapper
AUSCERT has developed a wrapper program to help prevent programs from
being exploited using the vulnerability described in this advisory.
This wrapper, including installation instructions, can be found at:
ftp://ftp.auscert.org.au/pub/auscert/tools/overflow_wrapper.c
This replaces the chfn program with a wrapper which checks the
length of the command line arguments passed to it. If an argument
exceeds a certain predefined value (MAXARGLEN), the wrapper exits
without executing the chfn command. The wrapper program can also
be configured to syslog any failed attempts to execute chfn with
arguments exceeding MAXARGLEN. For further instructions on using
this wrapper, please read the comments at the top of overflow_wrapper.c.
When compiling overflow_wrapper.c for use with HP-UX chfn, AUSCERT
recommends defining MAXARGLEN to be 16.
The MD5 checksum for Version 1.0 of overflow_wrapper.c is:
MD5 (overflow_wrapper.c) = f7f83af7f3f0ec1188ed26cf9280f6db
AUSCERT recommends that until vendor patches can be installed, sites
requiring the chfn functionality apply this workaround.
4. Additional measures
Most Unix systems ship numerous programs which have setuid or
setgid privileges. Often the functionality supplied by these
privileged programs is not required by many sites. The large number
of privileged programs that are shipped by default are to cater for
all possible uses of the system.
AUSCERT encourages sites to examine all the setuid/setgid programs
and determine the necessity of each program. If a program does not
absolutely require the setuid/setgid privileges to operate (for
example, it is only run by the root user), the setuid/setgid
privileges should be removed. Furthermore, if a program is not
required at your site, then all execute permissions should be removed.
A sample command to find all setuid/setgid programs is (run as root):
# find / \( -perm -4000 -o -perm -2000 \) -exec ls -ld {} \;
It is AUSCERT's experience that many vulnerabilities are being
discovered in setuid/setgid programs which are not necessary for the
correct operation of most systems. Sites can increase their security
by removing unnecessary setuid/setgid programs.
For example, the functionality provided by the chfn program is not
needed by many sites since the user information stored in the password
file, which chfn is used to change, is typically static. If sites
had previously disabled the chfn program, they would not have been
vulnerable to this latest exploit.
----------------------------------------------------------------------------
AUSCERT thanks Hewlett-Packard for their continued assistance and technical
expertise essential for the production of this advisory.
----------------------------------------------------------------------------
[ End AUSCERT Advisory ]
*******************************************************************************
[ Start CERT Advisory ]
2. HP Remote Watch Vulnerabilities
=============================================================================
CERT(sm) Vendor-Initiated Bulletin VB-96.20
December 12, 1996
Topic: Security Vulnerabilities in HP Remote Watch
Source: Hewlett-Packard Company
To aid in the wide distribution of essential security information, the CERT
Coordination Center is forwarding the following information from
Hewlett-Packard Company. Hewlett-Packard urges you to act on this information
as soon as possible. Their contact information is included in the forwarded
text below; please contact them if you have any questions or need further
information.
=======================FORWARDED TEXT STARTS HERE============================
===============================================================================
Document Id: [HPSBUX9610-039]
Date Loaded: [10-24-96]
Description: Security Vulnerabilities in HP Remote Watch
===============================================================================
--------------------------------------------------------------------------
HEWLETT-PACKARD SECURITY ADVISORY: #000039, 24 October 1996
--------------------------------------------------------------------------
Hewlett-Packard recommends that the information in the following
Security Advisory should be acted upon as soon as possible. Hewlett-
Packard will not be liable for any consequences to any customer
resulting from customer's failure to fully implement instructions in this
Security Advisory as soon as possible.
Permission is granted for copying and circulating this advisory to
Hewlett-Packard (HP) customers (or the Internet community) for the
purpose of alerting them to problems, if and only if, the advisory is
not edited or changed in any way, is attributed to HP, and provided such
reproduction and/or distribution is performed for non-commercial
purposes.
Any other use of this information is prohibited. HP is not liable
for any misuse of this information by any third party.
_______________________________________________________________________
PROBLEM: Vulnerability in HP Remote Watch in 9.X releases of HP-UX
PLATFORM: HP 9000 series 300/400/700/800s
DAMAGE: Vulnerabilities in HP Remote Watch exists allowing users to
gain additional privileges.
SOLUTION: Do not use Remote Watch.
_______________________________________________________________________
I. Remote Watch Update
A. Problem description
A recent mailing list disclosure described two vulnerabilities in
which HP Remote Watch allows unauthorized root access. The first was
via a socket connection on port 5556. The second was as a result of
using the showdisk utility, which is part of the Remote Watch product.
It has been found that HP9000 Series 300, 400, 700, and 800 systems
running only HP-UX Release 9.X have this vulnerability.
B. Fixing the problem
This vulnerability can only be eliminated from releases 9.X of HP-UX
which are using Remote Watch by disabling the entire product. The
default location for this product is /usr/remwatch/ .
Removal can be accomplished (as root) with the following:
NOTE: Do not run the standard rmfn command as HP has discovered
problems with its inability to handle programs with active executables.
Instead, run (with no options):
/usr/remwatch/bin/removeall
This runs a Remote Watch script called "unconfigure" to stop actively
running programs, then proceeds to remove all files including the
filesets.
The administrator should also perform both of the following steps:
1. Remove or comment out the following entry in /etc/inetd.conf
file:
rwdaemon stream tcp nowait root /usr/remwatch/bin/rwdaemon rwdaemon
2. Have inetd re-read its configuration file by executing at the
prompt:
inetd -c
This is the official recommendation from Hewlett-Packard Company.
C. Current product status
Remote Watch was last released from the labs in August of 1993.
In December 1994 customers were informed of pending product
obsolescence. Hewlett-Packard recommends that all customers
concerned with the security of their HP-UX systems with Remote
Watch configured on it perform the actions described herein as
soon as possible. Again, no patches will be available for any
versions of HP-UX.
Since the functionality of HP Remote Watch software has now been
replicated in other tools that handle system management more
effectively there is no longer a sufficient need for HP Remote
Watch. Most of the functionality is now provided by the Systems
Administration Manager (SAM) tool, available at no charge as part
of the HP-UX operating system, or by the HP OpenView
OperationsCenter application.
If further assistance is desired please contact your HP Support
Representative.
D. HP SupportLine
To subscribe to automatically receive future NEW HP Security
Bulletins from the HP SupportLine mail service via electronic mail,
send an email message to:
support@us.external.hp.com (no Subject is required)
Multiple instructions are allowed in the TEXT PORTION OF THE MESSAGE,
here are some basic instructions you may want to use:
To add your name to the subscription list for new security bulletins,
send the following in the TEXT PORTION OF THE MESSAGE:
subscribe security_info
To retrieve the index of all HP Security Bulletins issued to date,
send the following in the TEXT PORTION OF THE MESSAGE:
send security_info_list
To get a patch matrix of current HP-UX and BLS security patches
referenced by either Security Bulletin or Platform/OS, put the
following in the text portion of your message:
send hp-ux_patch_matrix
World Wide Web service for browsing of bulletins is available via
our URL:
http://us.external.hp.com
Choose "Support news", then under Support news,
choose "Security Bulletins"
E. To report new security vulnerabilities, send email to
security-alert@hp.com
Please encrypt exploit information using the security-alert PGP
key, available from your local key server, or by sending a
message with a -subject- (not body) of 'get key' (no quotes) to
security-alert@hp.com.
_______________________________________________________________________
========================FORWARDED TEXT ENDS HERE=============================
[ End CERT Advisory ]
_______________________________________________________________________________
CIAC wishes to acknowledge the contributions of AUSCERT, CERT, and HP 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
E-mail: ciac@llnl.gov
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: http://ciac.llnl.gov/
Anonymous FTP: ciac.llnl.gov (128.115.19.53)
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
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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;
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(SPI) software updates, new features, distribution and
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4. SPI-NOTES, for discussion of problems and solutions regarding the
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Our mailing lists are managed by a public domain software package
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CIAC-BULLETIN, CIAC-NOTES, SPI-ANNOUNCE or SPI-NOTES for list-name and
valid information for LastName FirstName and PhoneNumber when sending
E-mail to ciac-listproc@llnl.gov:
subscribe list-name LastName, FirstName PhoneNumber
e.g., subscribe ciac-notes OHara, Scarlett W. 404-555-1212 x36
You will receive an acknowledgment containing address, initial PIN,
and information on how to change either of them, cancel your
subscription, or get help.
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 http://www.first.org/.
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
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LAST 10 CIAC BULLETINS ISSUED (Previous bulletins available from CIAC)
H-05: Internet Hoaxes
H-07: Sendmail SIGHUP-smtpd Vulnerability
H-08: lpr Buffer Overrun Vulnerability
H-09: HP 9000 Access Vulnerability
H-10: HP-UX Security Vulnerabilities (passwd, fpkg2swpkg, newgrp)
H-11: sendmail Group Permissions Vulnerability
H-12: IBM AIX(r) 'SYN Flood' and 'Ping o' Death' Vulnerabilities
H-13: IBM AIX(r) Security Vulnerabilities (gethostbyname, lquerypv)
H-14: SGI IRIX Vulnerabilities (systour, OutOfBox, cdplayer, datman)
H-15: Korn Shell (ksh) suid_exec Vulnerability
RECENT CIAC NOTES ISSUED (Previous Notes available from CIAC)
Notes 07 - 3/29/95 A comprehensive review of SATAN
Notes 08 - 4/4/95 A Courtney update
Notes 09 - 4/24/95 More on the "Good Times" virus urban legend
Notes 10 - 6/16/95 PKZ300B Trojan, Logdaemon/FreeBSD, vulnerability
in S/Key, EBOLA Virus Hoax, and Caibua Virus
Notes 11 - 7/31/95 Virus Update, Hats Off to Administrators,
America On-Line Virus Scare, SPI 3.2.2 Released,
The Die_Hard Virus
Notes 12 - 9/12/95 Securely configuring Public Telnet Services, X
Windows, beta release of Merlin, Microsoft Word
Macro Viruses, Allegations of Inappropriate Data
Collection in Win95
Notes 96-01 - 3/18/96 Java and JavaScript Vulnerabilities, FIRST
Conference Announcement, Security and Web Search
Engines, Microsoft Word Macro Virus Update
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