unset the KRB_CONF envariable if using kerberos so we don't get

spoofed into using a bogus server

sudo.c

@@ -158,6 +158,9 @@ struct env_table badenv_table[] = {
 #if defined (__osf__) && defined(__alpha)
     { "_RLD_", 5 },
 #endif /* __alpha && __alpha */
+#ifdef HAVE_KERB4
+    { "KRB_CONF", 8 },
+#endif
     { "IFS=", 4 },
     { (char *) NULL, 0 }
 };