SGI security Frequently Asked Questions (FAQ)
The SGI FAQ group
Last-modified: Sat Jan 6 1:00:03 CST 2001
Posting-Frequency: Twice monthly
URL: http://www-viz.tamu.edu/~sgi-faq/
SGI security Frequently Asked Questions (FAQ)
This is one of the Silicon Graphics FAQ series, which consists of:
SGI admin FAQ - IRIX system administration
SGI apps FAQ - Applications and miscellaneous programming
SGI audio FAQ - Audio applications and programming
SGI diffs FAQ - Changes to the other FAQs since the last posting
SGI graphics FAQ - Graphics and user environment customization
SGI hardware FAQ - Hardware
SGI impressario FAQ - IRIS Impressario
SGI inventor FAQ - IRIS Inventor
SGI misc FAQ - Introduction & miscellaneous information
SGI movie FAQ - Movies
SGI performer FAQ - IRIS Performer
SGI pointer FAQ - Pointer to the other FAQs
SGI security FAQ - IRIX security
Read the misc FAQ for information about the FAQs themselves. Each FAQ is
posted to comp.sys.sgi.misc and to the news.answers and comp.answers
newsgroups (whose purpose is to store FAQs) twice per month. If you
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Topics covered in this FAQ:
---------------------------
-1- Where can I learn about IRIX and Unix security?
-2- How can I check my system for security problems?
-3- How can I configure IRIX to be more secure?
-4- How can I log more information about logins?
-5- How can I make an anonymous or restricted FTP account?
-6- How can I get X authorization to work?
-7- What security-related bugs does IRIX have?
-8- I think I've found a security hole in IRIX; whom should I notify?
-9- How can I get around the root and/or PROM passwords?
-10- What firewalls are available on SGI/IRIX platforms?
----------------------------------------------------------------------
Subject: -1- Where can I learn about IRIX and Unix security?
Date: Thu Dec 7 17:14:28 CST 2000
IRIX: Look in ftp://sgigate.sgi.com/Security/ and at
http://www.sgi.com/support/security/index.html for SGI security
advisories and patches. SGI also runs a mailing list called
"wiretap" for dissemination of IRIX security advisories from SGI;
its subscription address is <wiretap...@sgi.com>. An article in
the Jul/Aug 1994 Pipeline discusses general Unix security with some
IRIX-specific aspects.
Unix in general: Look in ftp://ftp.cert.org/,
ftp://ciac.llnl.gov/pub/ciac/ and http://www.8lgm.org/ for CERT, CIAC
and 8lgm material (respectively) and general security information and
tools. If you have a lot of spare time, consider the
comp.security.unix newsgroup and/or the bugtraq mailing list
(list...@netspace.org, archived at http://www.securityfocus.com/)
------------------------------
Subject: -2- How can I check my system for security problems?
Date: 04 May 1996 00:00:01 EST
Get Nate Sammons <na...@vis.colostate.edu>' 'rscan' (formerly
'securscan') from ftp://ftp.vis.colostate.edu/pub/rscan/ (and see its
documentation etc. at http://www.vis.colostate.edu/rscan/). It checks
for many bugs and problems, both specific to IRIX and generic to Unix.
Unfortunately, it has not been updated since April 1995 and will not
detect most holes discovered since then. You might also want to try a
generic Unix security-checking tool such as COPS, tiger or SATAN
and/or a password checker such as Crack. SGI's security page
referenced above gives their locations.
------------------------------
Subject: -3- How can I configure IRIX to be more secure?
Date: 30 Mar 1996 00:00:01 EST
Several aspects of SGI's default IRIX configuration were chosen for
convenience, not security. Unless your machine is not networked, you
may be more concerned about security than SGI assumed. Note that
these items have been discussed on Usenet many times, and Usenet
chatter is not a good way to change SGI policy. If they bother you,
complain to your sales rep and then fix them yourself as follows.
Under any version of IRIX,
- Several accounts come without passwords, including (but not limited
to) guest, 4Dgifts, demos, tutor, tour and particularly lp. Examine
/etc/passwd and lock all unnecessarily open accounts. Note that 1)
parts of IRIX (e.g. 'inst') use the open guest account by default,
and 2) remote 'lp' clients need access to the lp account to print,
so you'll need to make other arrangements. Completists may wish to
read CERT advisory CA-95:15, at
ftp://info.cert.org/pub/cert_advisories/CA-95%3A15.SGI.lp.vul, and
SGI advisory 19951002-01-I, at
ftp://sgigate.sgi.com/Security/19951002-01-I.
- 'xdm' does 'xhost +' by default when you log in. This allows anyone
to open windows on your display and even to record what you type at
your keyboard. Close this hole by removing the 'xhost +' from
/usr/lib/X11/xdm/Xsession, /usr/lib/X11/xdm/Xsession-remote and (in
IRIX 5.x) /usr/lib/X11/xdm/Xsession.dt. In IRIX 5.2 and later you
can use X authorization to control access to remote displays; see
below. In IRIX 5.1.x and earlier X authorization doesn't work, so
you'll need to use 'xhost' judiciously to get to remote displays:
say 'xhost +localhost' to run DGL programs and 'xhost +otherhost' to
display remote X programs.
- At least some of the possible default values of the PATH
environment variable begin with the current directory. (The system
interprets either a period or the empty string in any component of
PATH as the current directory. PATH is colon-separated, so if it
begins with a colon the first component is the empty string.) This
exposes you to Trojan horse programs. Set PATH to a safe value
(remove the current directory, or at least move it to the end) in
/etc/cshrc and/or /etc/profile for regular users and /.login for
root.
- By default, /etc/config/ypbind.options contains the -ypsetme
option. This allows someone who can fake your IP address to change
your YP binding. Remove the -ypsetme option to close the hole and
add the -s option for a little extra protection. Comment out the
invocations of 'ypset' in /var/yp/make.script and /var/yp/ypmake to
avoid error messages. If your site runs ypbind with the -v
(verbose) option, you may also want to add 'YPSET=true' to
/etc/config/ypmaster.options and comment out the 'ypset' line in
/var/yp/ypmake. See the ypbind(1) and ypset(1) manpages for more.
- If you use SLIP (see slip(1M)), be sure that SLIP accounts' home
directories are not world-writable. SLIP accounts are uid 0, so
it's bad if just anyone can mess with their .forward files and the
like. /tmp, which is recommended in the "IRIX Advanced Site and
Server Administration Guide", is necessarily world-writable and a
bad choice. You may want to make an empty, root-owned, mode 755
directory to the effect of /usr/slip and use that. Any number of
SLIP accounts can use a single home directory without conflict.
- Add '-a' to the rlogind and rshd lines in /etc/inetd.conf to require
remote hostnames and addresses to match. You *might* want to
disallow .rhosts files by adding the '-l' flag as well, but this
removes real functionality and should not be done without reason.
See the rlogind(1M) and rshd(1M) manpages. Note that rlogind's '-l'
flag does not work in IRIX 5.2. It does work in IRIX 5.3.
- The default root crontab in current IRIXes
(/var/spool/cron/crontabs/root) creates the SYSLOG and cron log with
group and world read permission. Change the '033' on lines 25 and 27
to '077' to prevent non-superusers from reading these files.
- By default, xdm looks for X terminal login requests on port
177. This is no different (for security purposes) than allowing
rlogin or telnet connections, but it might be undesirable in some
environments. Edit /var/X11/xdm/Xaccess to restrict this access,
e.g. by placing a `!' in front of each of the two lines which begin
with an asterisk to prevent all XDMCP requests.
- /etc/init.d/rmtmpfiles resets the permissions on /tmp and /var/tmp
at every bootup. By default, permissions are set to 1777; the '1'
means sticky, so one user can't remove another's temporary files. If
one does 'chkconfig nostickytmp on', permissions are set to 777 and
any user can remove another's temporary files. Don't do this: it
allows a variety of attacks involving race conditions in setuid
programs. A related class of attacks is described in
ftp://ciac.llnl.gov/pub/ciac/bulletin/f-27.permissions-on-tmp.asc,
but note that Sun's tmpfs is not an essential component of the hole.
- Non-root users can give away files. This can be used to defeat
accounting and quotas. Set the 'restricted_chown' kernel variable to
1 to allow only root to give away files. This may break some
programs which depend on unrestricted chown, e.g. /bin/mail (when
delivering to an NFS volume without root access) as discussed in the
admin FAQ. (Thanks to Jonathan Rozes <jro...@tufts.edu> for this and
the next item.)
- NFS connections to unprivileged ports are accepted by default. Set
the 'nfs_portmon' kernel variable to 1 to reject NFS connections
to unprivileged ports.
- /etc/inetd.conf enables some unnecessary services. The 'echo'
and 'chargen' services can allow a denial-of-service attack, as
described, for example, in CERT advisory CA-96.01, at
ftp://ftp.cert.org/pub/cert_advisories/CA-96.01.UDP_service_denial.
To disable those particular services, comment out the lines which
begin with their names in /etc/inetd.conf and 'killall -HUP inetd'.
You may want to disable other unused UDP-based services as well.
- Many devices have permissions which might allow a user to monitor
another user via audio or video input, including
/dev/audio
/dev/dmrb
/dev/hdsp/*
/dev/vid
/dev/video
Bill Paul <wp...@ctr.columbia.edu>'s solution is to add the
following to /usr/lib/X11/xdm/Xstartup
chmod 600 /dev/audio /dev/hdsp/* /dev/video /dev/vid /dev/dmrb
chown $USER /dev/audio /dev/hdsp/* /dev/video /dev/vid /dev/dmrb
and the following to /usr/lib/X11/xdm/Xreset
chmod 600 /dev/audio /dev/hdsp/* /dev/video /dev/vid /dev/dmrb
chown root /dev/audio /dev/hdsp/* /dev/video /dev/vid /dev/dmrb
(Simon ? <si...@instrumatic.ch> pointed out that the chmod should
precede the chown to avoid a race condition.)
- Read the rest of the entries in this section and make the changes
they describe if appropriate.
Under IRIX 5.x or later only,
- Turn on shadow passwords, which are not used by default. Run
'pwconv' to move your passwords to /etc/shadow, where only root can
read them. Note that you'll have to update /etc/shadow by hand for
NIS users. See the pwconv(1M) and shadow(4) manpages.
- Limit the hosts from which portmap(1M) and rpcbind(1M) will accept
RPC requests by using the -a option in /etc/config/portmap.options.
For example, if your machine is www.xxx.yyy.zzz and your subnet is
www.xxx.yyy you can reject RPC requests from outside your subnet by
putting '-a 255.255.255.0 www.xxx.yyy.0' in that file. Despite the
file's name and the absence of any options in the rpcbind manpage,
this appears to work with rpcbind as well as portmap. Note also the
related putative bug under "security-related bugs" below.
This list is guaranteed to be incomplete. Keep your eyes open.
Similar lists are in SGI's security advisory 19950401-01-I, which is
at ftp://sgigate.sgi.com/Security/19950401-01-I, and a post by Dave
Olson <ol...@sgi.com>, a copy of which is at
ftp://viz.tamu.edu/pub/sgi/software/security/olson-security.
------------------------------
Subject: -4- How can I log more information about logins?
Date: 27 May 1996 00:00:01 EST
- 'last', 'who', etc. get remote login information from
/var/adm/utmpx and /var/adm/wtmp. That information is only logged
into these files if they already exist. To create them, do
'touch /var/adm/utmpx /var/adm/wtmpx'. The analogous files under
IRIX 4.0.x are /etc/xutmp and /etc/xwtmp.
- If you're running IRIX 5.3, install patch 420 to fix a bug which
causes xterm(1) to log logins incorrectly.
- As described in the login(1) manpage, you can add the line
'syslog=all' to /etc/config/login.options (IRIX 4.0.x) or change the
line 'SYSLOG=FAIL' in /etc/default/login to 'SYSLOG=ALL' (IRIX 5.x)
to log all login attempts, not just successful ones, in
/var/adm/SYSLOG. Under IRIX 5.x only, the same change in
/etc/default/su has the same effect on 'su' attempts.
- 'ftpd', 'rshd', 'tftpd' and 'fingerd' all have options ('-l' or
'-L') which cause them to log all accesses. See their manpages.
'ftpd' also has '-ll' and '-lll' options (undocumented before IRIX
5.x) which log individual file transfers and the sizes of those
files respectively. Add the options to the last fields (not the
second-to-last) of the appropriate lines of /etc/inetd.conf, then do
'killall -HUP inetd' or reboot.
- Consider using Wietse Venema's tcp_wrappers, at
ftp://ftp.win.tue.nl/pub/security/. This allows you not only to log
most types of connections, but to restrict connections from
particular hosts and prevent some forms of address spoofing.
README.IRIX in current versions of tcp_wrappers describes a number
of ways in which it does not work well with IRIX, some of them
serious. tcp_wrappers is still useful, but read README.IRIX
carefully and test your configuration to be sure it's working.
------------------------------
Subject: -5- How can I make an anonymous or restricted FTP account?
Date: 13 Aug 1995 00:00:01 EST
Read the ftpd(1M) manpage and/or the article in the March/April 1994
Pipeline. However, both discussions have a serious error: the ftp
account's home directory (/usr/people/ftp) should be owned and
writable only by root, NOT ftp. You might also want to make the 'pub'
directory "sticky" with 'chmod +t' (like /tmp and /var/tmp) so that
one user can't delete another's files. Two scripts which set up a
secure or restricted anonymous FTP account are at
ftp://viz.tamu.edu/pub/sgi/software/ftp/.
------------------------------
Subject: -6- How can I get X authorization to work?
Date: 24 Feb 1996 00:00:01 EST
Under IRIX 5.1.x or earlier, don't try. The MIT-MAGIC-COOKIE-1
protocol did not work, and DGL programs did not understand X
authorization.
Under IRIX 5.2, heed the wise words of Mark Kilgard of SGI's
X Window Systems group <m...@hoot.asd.sgi.com>:
The basic mechanism for the MIT-MAGIC-COOKIE-1 authorization protocol
is implemented by the X server, Xlib, and xdm, and does work in IRIX
5.x. MIT-MAGIC-COOKIE-1 is the only supported protocol.
Two caveats before I describe how to enable X authorization:
1) Old remote IRIS GL programs probably will not be able to connect to
the X server when X authorization is enabled. (More on this below.)
2) Due to a problem with how the local hostname is handled, to use X
authorization in the IRIX 5.x releases, you will need to make sure
your /etc/sys_id file has a simple hostname, ie. hoot instead of a
fully resolved hostname like hoot.asd.sgi.com This problem has
already been fixed for the next general release of IRIX.
TO ENABLE X AUTHORIZATION, do the following to your IRIX 5.2 system:
1) Edit /var/X11/xdm/xdm-config as root and change the line
saying
DisplayManager*authorize: off
to say
DisplayManager*authorize: on
2) Edit /var/X11/xdm/Xsession, /var/X11/xdm/Xsession-remote, and
/var/X11/xdm/Xsession.dt as root and change the line saying
/usr/bin/X11/xhost +
to say
#/usr/bin/X11/xhost +
This disables the "xhost +" by commenting out the command.
3) Make sure your /etc/sys_id file has no periods in it. For
example, change as root:
to say
hoot
4) Reboot the machine OR restart a new xdm and X server. This
can be done as root with the following command:
(/usr/gfx/stopgfx; killall xdm; /usr/gfx/startgfx) &
5) Log in. X authorization should be enabled.
If you want to disable X authorization and return to the default
system state where X clients can connect to the X server from any
machine, reverse the changes in steps 1 and 2 and repeat step 4.
If you want more information on X authorization, see the manpages for
xdm(1), Xserver(1), Xsgi(1), Xsecurity(1), xauth(1) and xhost(1).
X AUTHORIZATION AND REMOTE IRIS GL PROGRAMS: One of the major reaons
for Silicon Graphics shipping its window system so that an X client
from any machine could connect to the X server was because IRIS GL
programs running remote using the DGL (distributed GL) protocol didn't
interoperate with the X authorization mechanism; the dgld daemon that
would run on the machine with graphics hardware had no way to get the
correct X authorization information to connect to the X server.
This has been fixed for IRIX 5.2, but the fix only applies to IRIX 5
binaries running remotely on an IRIX 5.2 system connecting to an IRIX
5.2 X server. In particular, remotely run IRIX 4 IRIS GL binaries
will continue to not interoperate with an IRIX 5.2 X server (or a
pre-IRIX 5.2 X server). If you recompile your old IRIS GL binaries
on IRIX 5.2, they then will work remotely connecting to IRIX 5.2 X
servers running X authorization.
The bottom line is that if you want an IRIS GL program to run
remotely on an X server using X authorization, you need to make sure
the program is an IRIX 5 binary running on an IRIX 5.2 machine and
the machine with the X server is also an IRIX 5.2 machine.
To avoid a possible misconception: IRIS GL programs RUNNING LOCALLY
(ie, not using DGL) WILL WORK FINE on an IRIX 5.2 system no matter if
they are IRIX 4 or IRIX 5 binaries. The problem with X authorization
is only for REMOTE IRIS GL programs.
Also note that for X authorization to work for remote hosts, the
remote program must have access to the correct X authorization magic
cookie (normally read from ~/.Xauthority). If you don't have a
shared NFS mounted home directory, you'll probably need to use the
xauth command to transfer the X authorization magic cookie to the
remote ~/.Xauthority file.
THE FUTURE: Hopefully in the next general release of IRIX, a
mechanism to enable and disable X authorization using a chkconfig
option will be supported. The problem with /etc/sys_id not having
periods will definitely be fixed in the next general release of
IRIX. The problem with pre-IRIX 5.2 X servers and binaries not
interoperating with X authorization will likely not be fixed. Fixing
the problem required a DGL protocol extension which both the IRIS GL
program and dgld must know about; this can't be fixed in already
shipped software.
Under IRIX 5.3, do what you did for IRIX 5.2. There is no chkconfig
option for X authorization. The problem with periods in hostnames is
still present in 5.3 as such, but is fixed by patch 518. There is a
bug in NFS3 which truncates ~/.Xauthority files which is fixed by
patch 216. See also the descriptions of the shared memory hole and the
putative X authorization weaknesses below under "security-related
bugs".
------------------------------
Subject: -7- What security-related bugs does IRIX have?
Date: 4 Jun 1997 00:00:01 EST
(Thanks to Yuri Volobuev <volo...@t1.chem.umn.edu> for updating
several questions in this question.)
Some general comments before we start:
- IRIX is too complex for us to guarantee that this list is complete.
We only discuss problems we know about. We don't discuss insecurely
designed systems (like YP) or ways in which you might misconfigure
your system, only bugs. We don't discuss third-party software,
free or not.
- Prudence and space permit us to describe only how to close holes,
not to exploit them. Try comp.security.unix.
- Some of the fixes involve installing a new version of a setuid
binary. Be sure that you 1) make it executable, setuid and owned
by the correct user and group (or it won't work), and 2) remove the
old version so bad guys can't use it!
Now for the holes themselves:
- ftp://ftp.cert.org/pub/cert_advisories/CA-92:08.SGI.lp.vulnerability
describes problems with the permissions of 'lp'-related parts of
IRIX which allow anyone who can log in as lp to get root access.
They are fixed in IRIX 4.0.5. Briefly, the fix is
su root
cd /usr/lib
chmod a-s,go-w lpshut lpmove accept reject lpadmin
chmod go-ws lpsched vadmin/serial_ports vadmin/users vadmin/disks
cd /usr/bin
chmod a-s,go-w disable enable
chmod go-ws cancel lp lpstat
- ftp://ftp.cert.org/pub/cert_advisories/CA-93:17.xterm.logging.vulnerability
describes a hole in /usr/bin/X11/xterm which allows any user root
access. It is fixed in IRIX 5.x. A fixed version for 4.x is at
ftp://ftp.sgi.com/sgi/IRIX4.0/xterm/. The 'fix', incidentally, is
that logging is completely disabled.
- /usr/bin/under is an unused (!) part of 'rexd'. It is setuid root
and may allow root access, so 'chmod -s' it just in case. Note that
SGI ships IRIX with 'rexd' turned off because 'rexd' is itself a
security problem. It is not shipped in IRIX 5.x.
- ftp://ciac.llnl.gov/pub/ciac/bulletin/f-fy95/f-01.ciac-SGI-IRIX-serial-ports
describes a race condition in IRIX 4.0.x's
/usr/lib/vadmin/serial_ports which allows any user to become root
in IRIX 4.0.x. 'chmod 700' it to close the hole; it will still work
fine.
/usr/lib/vadmin/serial_ports is part of IRIX 4.0.x and should not
exist on IRIX 5.x systems, but some users have reported problems
with upgrading from 4.0.x to 5.x which leave old binaries behind.
If the file exists on your 5.x system, remove it. (5.x's
equivalent, /usr/Cadmin/bin/cports, does not have the problem.)
- /usr/bsd/rdist has several holes which allow any user root access in
all versions of IRIX before 5.3, including the 4.0.5 and 5.x
binaries on ftp.sgi.com.
Under IRIX 5.2, you can install patch 130 to close all known
holes. Under IRIX 4.0.x, you must close the hole with 'chmod -s'.
rdist will then work only when used by root. If your non-root users
need 'rdist', there is a free version, which does not need to be
setuid root and is thus free of all known holes, in
ftp://usc.edu/pub/rdist/. Make sure you get version 6.1 beta 3 or
later. IRIX 5.3's rdist is derived from this version and is thus
equally safe; presumably ordist is the IRIX 5.2-patch 130 rdist and
is also safe.
As for advisories, CERT advisory CA-91:20, at
ftp://ftp.cert.org/pub/cert_advisories/CA-91:20.rdist.vulnerability
is badly out of date, and
http://www.8lgm.org/advisories/[8lgm]-Advisory-1.UNIX.rdist.23-Apr-1991
and
http://www.8lgm.org/advisories/[8lgm]-Advisory-26.UNIX.rdist.20-3-1996.html
may not describe all of the known holes.
- The 'lpr' subsystem in every version of IRIX before 5.3 has several
holes which allow a non-root user to become root. Note that 'lp' is
SGI's usual printing system; you only need 'lpr' if you need to deal
with remote printers. If you don't need 'lpr', make sure it isn't
installed. (It lives in the eoe2.sw.lpr subsystem.) If you do need
'lpr', there are fixed versions at
ftp://ftp.sgi.com/sgi/IRIX4.0/lpr/lpr.latest.Z
ftp://ftp.sgi.com/sgi/IRIX5.0/lpr/lpr.latest.Z
The versions dated 29 and 26 April, respectively, work with NIS
(YP). The IRIX 5.x version is also available as patch 131.
- /usr/sbin/cdinstmgr is setuid root in IRIX 4.0.5[A-F] and
/etc/init.d/audio is setuid root in IRIX 5.2. They are scripts;
setuid scripts are a well-known Unix security problem. IRIX ignores
the setuid bit by default, but 'chmod -s' the scripts just in case.
- ftp://sgigate.sgi.com/Security/19950209-01-P describes a bug in
colorview in IRIX 5.x before 5.3, which allows anyone to use it to
read any file regardless of permissions, and gives a fix.
- /usr/bin/newgrp is group-writable in IRIX 5.2. It doesn't need to
be, and it might be a problem depending on your use of group sys
and/or the presence of the 'sadc' bug (described elsewhere in this
list) on your system. 'chmod g-w' it.
- /usr/sbin/printers has a bug in IRIX 5.2 (and possibly earlier 5.x
versions) which allows any user to become root. Apply patch 5. You
might want to 'chmod -s' it while you're waiting.
- /usr/sbin/sgihelp has a bug in IRIX 5.2 (and possibly earlier 5.x
versions) which allows any user to become root. This is so bad that
the patch (#65, along with the prerequisite patch 34) is FTPable
from ftp://ftp.sgi.com/security/, and SGI is preparing a CD
containing only that patch. Call the TAC if you can't FTP. You
should 'chmod -x /usr/sbin/sgihelp' while you're waiting.
- The inst which comes with patch 34 (for IRIX 5.2), which is required
for installation of all other patches (even those with lower
numbers) saves old versions of binaries in /var/inst/patchbase. It
does not remove execution or setuid permissions! 'chmod 700' that
directory so evil users can't get to the old binaries. The bug is
fixed in patch 82 for IRIX 5.2 and in IRIX 5.3.
- http://www.8lgm.org/advisories/[8lgm]-Advisory-11.UNIX.sadc.07-Jan-1992
describes a hole in the System V system activity reporting program
/usr/lib/sa/sadc which allows any user to write files with the
permissions of that program. This bug is present in all versions of
IRIX through 5.3, but since /usr/lib/sa/sadc is only setgid sys it
can only be used to change groups sys-writable files or write files
in group sys-writable directories. If you don't use the system
activity reporter you might want to 'chmod -s /usr/lib/sa/sadc' just
to be safe. Because this hole isn't serious it isn't scheduled to be
closed, but write permission for group sys has been removed from
most directories where it wasn't necessary in IRIX 5.3, and a few
more (/dev/*dsk) will be fixed in a later release.
- /usr/etc/mount_dos, IRIX's DOS-filesystem floppy mounter, has a
serious bug in IRIX 5.2 (and probably earlier releases of 5.x as
well) which allows anyone with an account on and physical access to
a machine with a floppy drive root access. This bug can be fixed
with patch 167 and is reportedly fixed in IRIX 5.3. Perhaps the
easiest interim "fix" (which essentially disables all removable
media drives) is to disable mediad: "mediad -k" kills the current
instance of mediad, and "chkconfig mediad off" prevents mediad from
starting during the next reboot.
- ftp://ftp.cert.org/pub/cert_advisories/CA-95%3A17.rpc.ypupdated.vul
describes a security hole which is present in /usr/etc/rpc.ypupdated
in all versions of IRIX. It is completely unnecessary in most
networks; the only instance that we could think of that might
require this daemon would be NIS networks that include Sun diskless
clients. You should probably comment it out of /etc/inetd.conf, or
just not install the nfs.sw.nis subsystem, of which it is a part. It
is commented out by default in IRIX 5.3.
- ftp://sgigate.sgi.com/Security/19950301-01-P373
describes a bug in /usr/lib/desktop/permissions in IRIX 5.2, 6.0 and
6.0.1 which allows any user to change the permissions of any file to
anything. (Click on "Apply" twice fast, then click "Cancel" to
dismiss the root password window.) It is fixed in patch 373 for IRIX
5.2, 6.0 and 6.0.1 and in IRIX 5.3. Until you patch or upgrade,
'chmod -s' it to close the hole.
- sendmail is a complex program in which new security holes are
discovered almost daily. Some of these holes enable unprivileged
users (and in one case even *remote* users!) to gain root access.
The safest course of action seems to be to use the most recent
sendmail possible.
Recent sendmail patches also fix a bug present in every IRIX
sendmail before 5.3: /usr/bsd/newaliases (which is just a symlink to
/usr/lib/sendmail) creates /etc/aliases.{dir,pag} with mode 666. Any
user can thus add aliases which can run programs or steal mail.
Close the hole with 'chmod go-w /etc/aliases.dir /etc/aliases.pag'.
sendmail doesn't change those files' permissions once they exist, so
a) you should check them even if you've installed a sendmail in
which the problem is fixed and b) once they exist and have proper
permissions, you're OK.
- /usr/etc/arp has a hole in IRIX 5.2 and earlier which allows any
user to read files with 'arp's permissions, i.e. group sys. Close
the hole with 'chmod -s'. This prevents non-root users from using
'arp' at all, but they don't generally need it. The hole is closed
in IRIX 5.3.
- SoftWindows 1.25 (which is distributed by SGI in Desktop Support
Environment 1.0 and HotMix 11) includes an installation script which
executes Netscape as root. This can be used to gain root access,
etc. Patch 905 (if your Softwindows is installed as the
"SoftWindows" subsystem) or 908 (if it's in the "swin" subsystem)
fixes the script.
- ftp://ftp.cert.org/pub/cert_advisories/CA-95:14.Telnetd_Environment_Vulnerability
describes a vulnerability in telnetd which is present in IRIX before
6.2. A remote user can use telnet/telnetd to pass environment
variables to login which cause login to use an arbitrary shared
library. If the same user can place a shared library on the system
running telnetd (e.g. by depositing it in an incoming FTP
directory), that user can gain root permissions. There is a related
hole in login(1): it allows one to set LD_ envariables from the
command line, and, if they are already present in its environment,
passes them to programs which it invokes. Patches 1010, 1020 and
1143 for various versions of IRIX close the holes, as does IRIX 6.2.
- ftp://sgigate.sgi.com/Security/19960101-01-PX describes a hole in
the objectserver which allows a local or remote user to become
root. Patch 1052 to IRIX 5.2, 6.0 and 6.0.1, patch 1048 to IRIX 5.3
and patch 1090 to IRIX 6.1 close the hole. Note that patch 1048
(and perhaps its cousins) comes with a mediad which doesn't
properly handle audio CDs, and that its successor, patch 1096
(successors to 1052 and 1090 are not yet available) breaks
cformat(1M); see the admin FAQ.
- ftp://sgigate.sgi.com/Security/19960102-01-P
describes a hole in /usr/pkg/bin/pkgadjust (part of the SVR4 pkg
system, in eoe2.sw.oampkg, not installed by default) which allows
local users to overwrite files and execute arbitrary programs as
root. To close the hole, either remove eoe2.sw.oampkg or 'chmod -s
/usr/pkg/bin/pkgadjust'. If you do leave eoe2.sw.oampkg installed,
note that /usr/pkg/bin/abspath is setuid root as well. This is not
yet known to be a security problem, but is certainly not necessary,
and the careful admin will want to 'chmod -s' it as well. Since
neither program needs to be setuid, no patch is necessary. Future
releases of IRIX will not install them setuid.
- ftp://sgigate.sgi.com/Security/19960301-01-P and
ftp://ftp.cert.org/pub/cert_advisories/CA-96.09.rpc.statd describe a
hole in rpc.statd (see statd(1M)), present in all IRIXes before 6.2,
which allows a remote user to mount denial-of-service attacks or
create or remove files as root. Patch 1226 (IRIX 5.2), 1128 (6.0 and
6.0.1) and 1391 (5.3) close the hole. There is no patch for IRIX
6.1. The hole is fixed in IRIX 6.2.
- The xdm(1) manpage(!) describes a bug in IRIX 5.x (at least) which
allows a user to connect to a local display even when X
authorization should prevent one from doing so. (Fortunately, this
doesn't work for remote displays.) Close the hole with patch 1075,
or just turn off shared memory transport by adding the option
'-shmnumclients 0' to the X command in /usr/lib/X11/xdm/Xservers.
See also the lengthy discussion of X authorization above and the
description of the putative X authorization weaknesses below.
- LicenseManager 2.0 (a prerequisite for some of the free software
on Silicon Surf) a) allows any user to manipulate licenses and, b)
when one adds a new license, may delete old, unrelated licenses. The
problem is fixed in LM 2.0.1. Also, LicenseManager 1.x through 3.0
have bugs in them which can allow any user to become root. 'chmod
-s /usr/etc/LicenseManager' will close them; however, this will
preclude any user other than root from using LicenseManager to
manipulate licenses.
- ftp://info.cert.org/pub/cert_advisories/CA-96.08.pcnfsd describes a
bug which allows remote users to run commands as root on a pcnfsd
server. The bug is present in the version of pcnfsd which SGI
provides for IRIX 5.3, but not in that for IRIX 6.2 (or other IRIX
6.x?). It is fixed by patch 1179 for IRIX 5.3.
- /usr/bin/rmail has a bug which allows a local user to assume the
permissions of group mail, and thus (most importantly) read anyone's
mail. It is fixed in patch 1273 for IRIX 5.2-6.1 and 1281 for 6.2.
- ftp://sgigate.sgi.com/Security/19960501-01-PX and
ftp://sgigate.sgi.com/Security/19960801-01-PX describe holes in the
desktop administration tools which allow users to change permissions
on and edit files which they do not own. They are closed by patches
1519, 1518, 1517 and 1516 for IRIX 5.2, 5.3, 6.1 and 6.2
respectively.
- /usr/bin/X11/cdplayer and /usr/sbin/datman (also known as 'cdman')
have security holes in them that can allow users to execute
arbitrary programs as root. At this time, SGI has not released
patches for these programs yet, so the way to close the hole is via
'chmod -s /usr/bin/X11/cdplayer /usr/sbin/datman'. This will
unfortunately prevent non-root users from using cdman, datman, and
cdplayer; other Motif-based CD players are available on the
Internet which may not share cdplayer's vulnerabilities.
These problems are described in more detail in AUSCERT advisories
ftp://ftp.auscert.org.au/pub/auscert/advisory/AA-96.11.SGI.cdplayer.vul
and
ftp://ftp.auscert.org.au/pub/auscert/advisory/AA-96.20.SGI.datman.cdman.vul
- /var/rfindd/fsdump has a security hole in it which allows users to
overwrite arbitrary files and (in so doing) gain root access.
'chmod -s /var/rfindd/fsdump' will close the hole and also disable
rfindd.
- /sbin/suid_exec, a component of ksh that assists ksh in running
setuid shell scripts, has a security hole in it that allows users
to execute arbitrary programs as root. 'chmod -s /sbin/suid_exec'
will close the hole and also prevent ksh from executing setuid
shell scripts. (Execution of setuid shell scripts is off by default
on most releases of IRIX anyway.)
- /usr/Cadmin/bin/csetup, the "EZsetup" system setup manager, has a
security hole in it that allows users to execute arbitrary programs
as root.
- ftp://sgigate.sgi.com/security/19961203-01-PX describes a vulnerability
in /usr/lib/print/netprint, which allows any local user to become root.
Apply following patch 1685 (for 5.3/6.1) or 2022 (for 6.2). 5.2 doesn't
have netprint. Note, that this patch may break printing. To fix it,
add this to the top of /etc/init.d/lp
TMPDIR=/var/tmp
export TMPDIR
HOME=/var/spool/lp
export HOME
LOGNAME=lp
export LOGNAME
then run "/etc/init.d/lp stop ; /etc/init.d/lp start"
These bugs have not yet been fixed:
- /usr/bin/lp has several bugs that allow any local user to gain lp
privileges. If you don't need its functionality, consider removing the
suid bit from lp. If you do need it, you can "wrap" the lp binary
with a wrapper that cleans up critical environment variables
(e.g. PATH), checks the command line for shell metacharacters and
length limits.
- The default root crontab contains a call to /usr/etc/fsr. By default,
under certain conditions it can be used to obtain root privileges.
Edit root's crontab and add "-f /var/adm/.fsrlast" option to the
fsr command line.
- /usr/etc/cvpcsd is part of the CaseVision WorkShop package. It's
invoked by inetd with root priviledges. It has a vulnerability that
allows any root priviledges. It has a vulnerability that allows any
local user to overwrite any file on the system, and, under certain
conditions, become root.
Check your /etc/inetd.conf for this or a similar line:
sgi_pcsd/1 dgram rpc/udp wait root ?/usr/etc/cvpcsd pcsd
-L
if it's there, consider commenting it out. (Don't forget to
'killall -HUP inetd' after you've commented it out.)
- /usr/lib/InPerson/inpview, part of the InPerson desktop conferencing
tool, has a vulnerability that allows any local user to become root.
If you don't need InPerson functionality, remove the suid bit from
inpview (with 'chmod u-s /usr/lib/InPerson/inpview'). If you do
need it, restrict execution privileges to the trusted group of
individuals that have access to the console.
- /usr/bin/startmidi that comes with the standard IRIX 5.3 distribution
has a vulnerability that allows any local user to become root.
However, startmidi that comes with Desktop Special Edition 1.1 is not
vulnerable to this problem. IRIX 6.2 doesn't seem to be vulnerable
either. Check your machine by running "showfiles | grep startmidi".
If your output is:
f 64563 18688 dmedia_eoe.sw.midi usr/sbin/startmidi
your machine is most likely not vulnerable to this problem. If you see
f 46022 18608 dmedia_eoe.sw.midi usr/sbin/startmidi
your system is probably vulnerable, so remove the suid bit from
startmidi (with 'chmod u-s /usr/sbin/startmidi'). If it's
neither of the above, remove the suid bit just to be safe. There's no
official advisory or workaround for this problem.
- /usr/lib/so_locations.old can acquire random permissions after an
'inst' session in IRIX 5.3, due to a linker bug. It may become both
executable and setuid and/or setgid. It is not a script but could be
used as one; setuid scripts are a well-known Unix security problem.
IRIX ignores the setuid bit by default, but 'chmod -xs' it just in
case. The linker bug should be fixed in IRIX 6.2.
- /usr/Cadmin/bin/csetup, the "EZsetup" system setup manager, has a
security hole in it that allows users to execute arbitrary programs
as root. 'chmod -s /usr/Cadmin/bin/csetup' will close the hole
but prevent non-root users from running csetup. This bug is present
in IRIX 5.3 and probably in later versions as well.
- xwsh recognizes escape sequences which remap keys. An evildoer
can place escape sequences in a file or filename which, when passed
to xwsh to be displayed, remap keys to unexpected strings or to
xwsh internal functions. The escape sequences are not displayed and
may not be detected by the victim.
Programs which can pass these escape sequences to xwsh include
'cat', 'more', /bin/mail and /usr/bsd/Mail, and other programs such
as mail and news agents which call these programs to display text.
Programs which display filenames, such as 'ls' and 'find', can pass
escape sequences in filenames to xwsh.
Programs which do not recognize the remapping sequences, such as
xterm and MediaMail, and programs which remove escape sequences
from displayed text or replace them with safe characters, such as
'ls' with the '-b' or '-q' option, 'more' with the '-r' option, the
'less' pager and the Elm mailer's built-in pager, are safe.
This vulnerability is inherent in the ANSI standard escape codes
which xwsh respects; any terminal or terminal emulator which
recognizes these sequences has this problem. Recognition of these
escape codes ought to be optional, e.g. controlled by an X
resource. It will be in IRIX 6.2 (although a cursory search of the
man page xwsh(1) does not reveal how to do so). No patch is planned
for earlier versions of IRIX.
The safest workaround is to use xterm instead of xwsh. The next best
is to run only safe programs and/or display only safe text in xwsh
windows. If you use xwsh, alias 'ls' to 'ls -b' and 'more' to 'more
-r'. You could alias 'cat' to 'cat -v', or (to avoid corrupting
files when using 'cat' in pipelines) train yourself not use 'cat' to
display files.
- ftp://ftp.cert.org/pub/cert_advisories/CA-95:13.syslog.vul
describes a problem with the syslog(3) system call in which data
passed to syslog(3) can corrupt the stack and cause execution of
arbitrary code. If a program will accept data from an untrusted
(even remote) user and pass it to syslog(3) without bounds checking,
a *very* clever user can usurp the permissions of that program.
The hole will be closed in IRIX 6.2. There are no patches for
current versions of IRIX, and none are planned, because SGI finds it
difficult to distribute an installable patch to libc.so (where
syslog(3) lives). However, patch 1146 prevents sendmail from passing
dangerous data to syslog(3) in the first place, which prevents
exploitation of the hole via sendmail only.
- /usr/lib/X11/app-defaults/ISDN, the X resources file for the ISDN
confidence test module which is part of at least some versions of
SGI's ISDN software (details welcome), is both executable and setuid
root. It is not a script but could be used as one; setuid scripts
are a well-known Unix security problem. IRIX ignores the setuid bit
by default, but 'chmod -xs' it just in case. This will be fixed in
IRIX 6.2.
- http://www.stardot.net/~hhui/SDN-advisories/SDN-2-sgi-videoframer a)
describes a hole in the VideoFramer development software which
allows a local user to overwrite files, and b) points out that VF
includes many setuid scripts, which are a well-known Unix security
problem (although not in the default IRIX configuration). Fix both
problems with 'chmod -s /usr/video/vfr/*'.
- /usr/gfx/setmon has holes (present at least in IRIX 5.3) which allow
a local user to read files which should be readable only by root and
to crash the machine. 'chmod -s' it. (Thanks to Hui-Hui Hu
<hh...@stardot.net>.)
- /usr/etc/uncompvm in IRIXes up to 5.3 and 6.1 is setgid sys. It
doesn't need to be (crash dumps are readable only by root, not by
group sys) so 'chmod -s' it. It will not be setgid sys in IRIX 6.2.
(Thanks to Hui-Hui Hu <hh...@stardot.net>.)
- par(1) will display data read by a setuid program, even if the
program would not itself have printed that data. One can thus use
par and a suitably leaky setuid program (known examples include
arp(1M), setmon(1G) and uncompvm(1M)) to read files for which one
would otherwise not have permission. This will be fixed by a
patch to IRIX 5.3 and in IRIX 6.2.
- ftp://ftp.cert.org/pub/cert_advisories/CA-96.19.expreserve describes
a bug in expreserve which allows any user to overwrite any file on
the system. ftp://sgigate.sgi.com/Security/19960802-01-I explains
that since SGI's expreserve is setgid sys rather than setuid root as
on some othere systems (yay SGI!), it can only overwrite files which
can be written by group sys. Since there are no important files
which can be written by group sys, no patch is planned. The bug will
be fixed in a future release. Make sure that there are, indeed, no
important files on your system which are writable by group sys. If
you don't need expreserve, 'chmod -s' it.
The following advisories describe holes whose presence in IRIX we
can't confirm or deny at present:
http://www.8lgm.org/advisories/[8lgm]-Advisory-12.UNIX.suid_exec.27-Jul-1991
ftp://ftp.cert.org/pub/cert_advisories/CA-94%3A15.NFS.Vulnerabilities
ftp://ftp.cert.org/pub/cert_bulletins/VB-95%3A08.X_Authentication_Vul
ftp://ftp.cert.org/pub/cert_advisories/CA-96.02.bind
------------------------------
Subject: -8- I think I've found a security hole in IRIX; whom should
I notify?
Date: 31 May 1995 00:00:01 EST
First, call the TAC as for any bug. Next, send email to
securit...@sgi.com. You can also notify CERT <ce...@cert.org>, who
will contact the appropriate people from their contact list. They may
take some time.
------------------------------
Subject: -9- How can I get around the root and/or PROM passwords?
Date: 20 Apr 1996 00:00:01 EST
To get around the root password, start 'inst' from an IRIX CD or tape
as you would if you wanted to install software. (See chapter 3 of the
Software Installation Administrator's Guide.) If you've set a PROM
password, you'll need to provide it or circumvent it first; see below.
Say 'admin shroot' to get a root shell. You can then do any of the
following:
- use 'passwd' to change root's password
- 'setenv TERM iris-tp' and 'vi/etc/passwd'
- if /etc/passwd is really hosed, 'mv' the remains out of the way and
'echo root::0:0:root:/:/bin/sh > /etc/passwd'.
Alternatively, if your machine is an NIS client you can change the uid
of an NIS account to 0 from the server and do a 'ypmake'.
If you've lost your PROM password but can still log in as root, you
can zero the PROM password with 'nvram passwd_key ""'. If not, you'll
have to disable the PROM password via the hardware. On a 4D/35 or
Crimson, find the battery which maintains the nvram ("non-volatile
RAM") and remove it. On an Indigo or Indy, find the nvram chip itself
and remove it. On an Indigo^2, remove the jumper described in the
owner's manual. This may be a good time to call SGI.
------------------------------
Subject: -10- What firewalls are available on SGI/IRIX platforms?
Date: 16 Mar 1996 00:00:01 EST
Ping Huang <psh...@sgi.com> writes:
SGI is an OEM for Gauntlet (from Trusted Information Systems), meaning
that SGI sells and supports Gauntlet directly. See
http://www.tis.com/docs/Products/gauntlet.html for general Gauntlet
product information. See your SGI sales person for specific
information about Gauntlet for IRIX.
I believe that is the only commercial firewall product currently
available, although there are freely distributable (but unsupported
and possibly dated) alternatives like the TIS Firewall Toolkit. If you
want more choices, please make your desires for availability on the
SGI/IRIX platform known to your favorite firewall vendor(s).
------------------------------
End of sgi/faq/security Digest
******************************
--
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Finger us for info on the SGI FAQs, or look in ftp://viz.tamu.edu/pub/sgi/.