-----BEGIN PGP SIGNED MESSAGE----- =============================================================================== Security Advisory CERT-NL =============================================================================== Author/Source : Rene Ritzen Index : S-98-18 Distribution : World Page : 1 Classification: External Version: 1 Subject : SGI Overflow vulnerability in suid_exec Date : 14-Apr-98 =============================================================================== By courtesy of Silicon Graphics, Inc. we received information on a Buffer Overflow Vulnerability in suid_exec CERT-NL recommends to perform the workaround outlined in the section temporary solution below. ______________________________________________________________________________ Silicon Graphics Inc. Security Advisory Title: suid_exec Buffer Overflow Title: AUSCERT AA-96.17 Number: 19980405-01-I Date: April 6, 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 suid_exec program is part of the Korn Shell (ksh) software distributions. Under normal operation, the suid_exec program will run shell scripts setuid. Unfortunately, a buffer overrun has been discovered in the suid_exec program which could allow arbitrary commands to be run as the privileged user root. 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. - - - -------------- - - - --- Impact --- - - - -------------- The suid_exec program is installed by default on all IRIX 5.x and 6.x systems. With a local account, the suid_exec buffer overrun vulnerability can be exploited locally and remotely. The suid_exec buffer overrun vulnerability can be utilized to execute commands with root privileges. The suid_exec buffer overrun vulnerability has been publicly discussed in Usenet newsgroups and mailing lists and also reported in AUSCERT Security Advisory AA-96.17. - - - -------------------------- - - - --- Temporary Solution --- - - - -------------------------- To disable the programs that are believed to be vulnerable, use the following steps. 1) Become the root user on the system. % /bin/su - Password: # 2) Change the setuid root permissions on the program. # /bin/chmod 400 /sbin/suid_exec ************ *** NOTE *** ************ Removing these permissions from suid_exec will stop non-root users from executing setuid/setgid shell scripts and scripts upon which read permissions have not been set. 3) Confirm the new permissions on the program. # ls -la /sbin/suid_exec -r-------- 1 root sys 14384 May 30 1996 /sbin/suid_exec 4) Using the find command, locate any additional copies of suid_exec and disable them. Note that this is one long command, though we have separated it onto two lines using backslashes. # find / -local -type f -name suid_exec \ -print -ok chmod 400 '{}' \; This command will find all files on a system that are - only in the local file system you name (/ -local) - regular files (-type f) - named appropriately (-name suid_exec) Once found, those files will - have their names printed (-print) - have their modes changed, but only if you type `y' in response to the prompt (-ok chmod 400 '{}' \;) 5) Return to previous level. # exit $ - - - ---------------- - - - --- Solution --- - - - ---------------- The suid_exec program is considered freeware and will not be patched. As freeware software, all reasonable efforts will be made to address the issue in future versions of the software. OS Version Vulnerable? Patch # Other Actions ---------- ----------- ------- ------------- IRIX 3.x no IRIX 4.x no IRIX 5.0.x yes not avail Note 1 IRIX 5.1.x yes not avail Note 1 IRIX 5.2 yes not avail Note 1 IRIX 5.3 yes not avail Note 1 IRIX 6.0.x yes not avail Note 1 IRIX 6.1 yes not avail Note 1 IRIX 6.2 yes not avail Note 1 IRIX 6.3 yes not avail Note 1 IRIX 6.4 yes not avail Note 1 Notes: 1) Freeware upgrades should be applied. - - - ------------------------ - - - --- Acknowledgments --- - - - ------------------------ Silicon Graphics wishes to thank AUSCERT for their assistance in this matter. - - - ----------------------------------------------------------- - - - --- Silicon Graphics Inc. 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