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______________________________________________________________________________

                Silicon Graphics Inc. Security Advisory



        Title:   IRIX 6.3 & 6.4 mailcap vulnerability

        Number:  19980403-01-PX

        Date:    April 2, 1998

______________________________________________________________________________



Silicon Graphics provides this information freely to the SGI user community

for its consideration, interpretation, implementation and use.   Silicon

Graphics recommends that this information be acted upon as soon as possible.



Silicon Graphics provides the information in this Security Advisory on

an "AS-IS" basis only, and disclaims all warranties with respect thereto,

express, implied or otherwise, including, without limitation, any warranty

of merchantability or fitness for a particular purpose.  In no event shall

Silicon Graphics be liable for any loss of profits, loss of business, loss

of data or for any indirect, special, exemplary, incidental or consequential

damages of any kind arising from your use of, failure to use or improper

use of any of the instructions or information in this Security Advisory.

______________________________________________________________________________





- - -----------------------

- - --- Issue Specifics ---

- - -----------------------



The System Manager sysmgr(1M) provides a web-browser-like GUI interface to

tasks that help you administer an SGI workstation. sysmgr(1M) uses multiple

tools to manage its GUI interface, two of them being runtask(1M) and

runexec(1M).



By mimicking the descriptor files of runtask(1M) or runexec(1M), an SGI user

browsing web pages or reading email can inadvertently download a

"trojan horse" runtask(1M) or runexec(1M) descriptor file. The "trojan horse"

descriptor file will execute a local System Manager Task with the privileges

of the user web browsing and can lead to a local root compromise.



Silicon Graphics Inc. has investigated the issue and recommends the

following steps for neutralizing the exposure.  It is HIGHLY RECOMMENDED

that these measures be implemented on ALL vulnerable SGI systems.  This

issue will be corrected in future releases of IRIX.





- - --------------

- - --- Impact ---

- - --------------



All IRIX 6.3/6.4 users that have Mailcap entries for x-sgi-task

and x-sgi-exec have this vulnerability. On IRIX 6.3/6.4, these vulnerable

Mailcap entries are installed by default in /usr/local/lib/netscape/mailcap .

Users can add their own Mailcap entries in their home directories

($HOME/.mailcap) and these need to be inspected for the vulnerable x-sgi-task

and x-sgi-exec entries.



By default, this vulnerability requires an IRIX 6.3/6.4 user to use

Netscape Navigator to web browse or read email from a malicious site

and download a "trojan horse" System Manager Task which will execute

locally with the privileges of the user web browsing. If the user is a

privileged or root user, the "trojan horse" System Manger Task will execute

with root privileges and can lead to a root compromise.





- - --------------------------

- - --- Temporary Solution ---

- - --------------------------



Although patches are available for this issue, it is realized that

there may be situations where installing the patches immediately may

not be possible.





     1) Become the root user on the system.



                % /bin/su -

                Password:

                #



     2) Edit the default Mailcap file.



                # vi /usr/local/lib/netscape/mailcap



     3) Remove the following vulnerable mailcap entries:



                application/x-sgi-task; /usr/sysadm/bin/runtask %s; \

                    description="System Administration Task"



                application/x-sgi-exec; /usr/sysadm/bin/runexec %s; \

                    description="System Administration Executable"



     4) Find any additional mailcap files and remove any vulnerable entries.



        You will need to run the find(1) command on each system you

        maintain because the command examines files on local disks only.



        Note that this is one long command, though we have separated it

        onto three lines using backslashes.



                 # find / -local -type f  -name 'mailcap'  -o \

                   -name '.mailcap' -exec egrep 'runexec|runtask' {} \

                   /dev/null \;



        This command will find all files on a system that:

            are only in the local file system (/ -local)

            are regular files (-type f)

            have the name "mailcap" (-name 'mailcap') or the name ".mailcap"



        Once found, those files will be searched for the string "runexec" or

        "runtask" (-exec egrep 'runexec|runtask' {}) and have their path names

        printed .



        The addition of /dev/null as an argument causes grep to list the

        full pathname of any file containing the string, rather than just the

        basename.



        Edit the files that have the pathnames printed and remove any

        vulnerable runtask/runexec mailcap entries.



      5) Return to previous level.



                # exit

                $





- - ----------------

- - --- Solution ---

- - ----------------



   OS Version     Vulnerable?     Patch #      Other Actions

   ----------     -----------     -------      -------------



   IRIX 3.x          no

   IRIX 4.x          no

   IRIX 5.0.x        no

   IRIX 5.1.x        no

   IRIX 5.2          no

   IRIX 5.3          no

   IRIX 6.0.x        no

   IRIX 6.1          no

   IRIX 6.2          no

   IRIX 6.3          yes           2336

   IRIX 6.4          yes           2339



Patches are available via anonymous FTP and your service/support provider.



The SGI anonymous FTP site is sgigate.sgi.com (204.94.209.1) or its

mirror, ftp.sgi.com.   Security information and patches can be found

in the ~ftp/security and ~ftp/patches directories, respectfully.







                 ##### Patch File Checksums ####



The actual patch will be a tar file containing the following files:



Filename:                 README.patch.2336

Algorithm #1 (sum -r):    15417 8 README.patch.2336

Algorithm #2 (sum):       21104 8 README.patch.2336

MD5 checksum:             C5FCA39F205EF1C306F28E95C811150C



Filename:                 patchSG0002336

Algorithm #1 (sum -r):    64988 2 patchSG0002336

Algorithm #2 (sum):       38657 2 patchSG0002336

MD5 checksum:             C38D6B81878377F470D1CC0ED43C8227



Filename:                 patchSG0002336.idb

Algorithm #1 (sum -r):    05931 2 patchSG0002336.idb

Algorithm #2 (sum):       54651 2 patchSG0002336.idb

MD5 checksum:             0C821C1BC07C08F279288F86E9807C93



Filename:                 patchSG0002336.netscape_gold_sw

Algorithm #1 (sum -r):    52912 20 patchSG0002336.netscape_gold_sw

Algorithm #2 (sum):       51500 20 patchSG0002336.netscape_gold_sw

MD5 checksum:             88CABDD9E4669CC6303876D77E491E4F



Filename:                 README.patch.2339

Algorithm #1 (sum -r):    11695 8 README.patch.2339

Algorithm #2 (sum):       21823 8 README.patch.2339

MD5 checksum:             114563D0D67F80E371C71EF3E6262900



Filename:                 patchSG0002339

Algorithm #1 (sum -r):    37814 2 patchSG0002339

Algorithm #2 (sum):       40753 2 patchSG0002339

MD5 checksum:             E0B519F8ECD83396E29DFE07DF23517E



Filename:                 patchSG0002339.idb

Algorithm #1 (sum -r):    59311 2 patchSG0002339.idb

Algorithm #2 (sum):       54667 2 patchSG0002339.idb

MD5 checksum:             8E39530FD44C9087F0C07B1F75043764



Filename:                 patchSG0002339.netscape_gold_sw

Algorithm #1 (sum -r):    39233 20 patchSG0002339.netscape_gold_sw

Algorithm #2 (sum):       53498 20 patchSG0002339.netscape_gold_sw

MD5 checksum:             7FF56E22472B0797499920BAAB8CA9C5





- - - ------------------------

- - - --- Acknowledgments ---

- - - ------------------------



Silicon Graphics wishes to thank the CERT Coordination Center, and

AUSCERT for their assistance in this matter.





- - - -----------------------------------------------------------

- - - --- Silicon Graphics Inc. Security Information/Contacts ---

- - - -----------------------------------------------------------



If there are questions about this document, email can be sent to

cse-security-alert@sgi.com.



                      ------oOo------



Silicon Graphics provides security information and patches for

use by the entire SGI community.  This information is freely

available to any person needing the information and is available

via anonymous FTP and the Web.



The primary SGI anonymous FTP site for security information and patches

is sgigate.sgi.com (204.94.209.1).  Security information and patches

are located under the directories ~ftp/security and ~ftp/patches,

respectively. The Silicon Graphics Security Headquarters Web page is

accessible at the URL http://www.sgi.com/Support/security/security.html.



For issues with the patches on the FTP sites, email can be sent to

cse-security-alert@sgi.com.



For assistance obtaining or working with security patches, please

contact your SGI support provider.



                      ------oOo------



Silicon Graphics provides a free security mailing list service

called wiretap and encourages interested parties to self-subscribe

to receive (via email) all SGI Security Advisories when they are

released. Subscribing to the mailing list can be done via the Web

(http://www.sgi.com/Support/security/wiretap.html) or by sending email

to SGI as outlined below.



% mail wiretap-request@sgi.com

subscribe wiretap 

end

^d



In the example above,  is the email address that you

wish the mailing list information sent to.  The word end must be on a

separate line to indicate the end of the body of the message. The

control-d (^d) is used to indicate to the mail program that you are

finished composing the mail message.





                      ------oOo------



Silicon Graphics provides a comprehensive customer World Wide Web site.

This site is located at http://www.sgi.com/Support/security/security.html.



                      ------oOo------



For reporting *NEW* SGI security issues, email can be sent to

security-alert@sgi.com or contact your SGI support provider.  A

support contract is not required for submitting a security report.



______________________________________________________________________________

  This information is provided freely to all interested parties and may

  be redistributed provided that it is not altered in any way, Silicon

  Graphics is appropriately credited and the document retains and

  includes its valid PGP signature.





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