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SGI security Frequently Asked Questions (FAQ)

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Archive-name: sgi/faq/security
Last-modified: Sat Jan 6 1:00:03 CST 2001
Posting-Frequency: Twice monthly
URL: http://www-viz.tamu.edu/~sgi-faq/

See reader questions & answers on this topic! - Help others by sharing your knowledge
    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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    ftp://viz.tamu.edu/pub/sgi/faq/
    ftp://rtfm.mit.edu/pub/usenet/news.answers/sgi/faq/

(rtfm.mit.edu is home to many other FAQs and informational documents,
and is a good place to look if you can't find an answer here.) The FAQs
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    http://www-viz.tamu.edu/~sgi-faq/

If you can't use FTP or WWW, send mail to mail-server@rtfm.mit.edu with
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command 'send usenet/news.answers/sgi/faq/misc' to get the SGI misc FAQ,
and similarly for the other FAQs. Send the command 'send
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"Accessing the Internet by E-Mail FAQ".

You may distribute the SGI FAQs freely and we encourage you to do so.
However, you must keep them intact, including headers and this notice,
and you must not charge for or profit from them. Contact us for other
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are certain to be out of date. The contents are accurate as far as we
know, but the usual disclaimers apply. Send additions and changes to
sgi-faq@viz.tamu.edu.

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-request@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 (listproc@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 <nate@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/, and SGI advisory 19951002-01-I, at ftp://sgigate.sgi.com/Security/. - '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 <jrozes@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/. 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 <wpaul@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 ? <simon@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/, and a post by Dave Olson <olson@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 <mjk@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: hoot.asd.sgi.com 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 <volobuev@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/ 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/ 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/ 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/ 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/ 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/ and ftp://ftp.cert.org/pub/cert_advisories/ 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/ 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/ and ftp://sgigate.sgi.com/Security/ 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/ 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 <hhui@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 <hhui@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/ describes a bug in expreserve which allows any user to overwrite any file on the system. ftp://sgigate.sgi.com/Security/ 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/ ftp://ftp.cert.org/pub/cert_bulletins/ ftp://ftp.cert.org/pub/cert_advisories/
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 security-alert@sgi.com. You can also notify CERT <cert@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 <pshuang@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 ****************************** -- The SGI FAQ group <sgi-faq@viz.tamu.edu> http://www-viz.tamu.edu/~sgi-faq/ Finger us for info on the SGI FAQs, or look in ftp://viz.tamu.edu/pub/sgi/.

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