The BIND DNS implementation does not randomize the UDP source port when doing remote queries, and the query id alone does not provide adequate randomization.
The lack of source port randomization reduces the amount of data the attacker needs to guess in order to successfully execute a DNS cache poisoning attack. This allows the attacker to influence or control the results of DNS queries being returned to users from target systems.
Limiting the group of machines that can do recursive queries on the DNS server will make it more difficult, but not impossible, for this vulnerability to be exploited.
To limit the machines able to perform recursive queries, add an ACL in named.conf and limit recursion like the following:
acl example-acl {
192.0.2.0/24;
};
options {
recursion yes;
allow-recursion { example-acl; };
};
Disclaimer: The data contained on this page is derived from the VuXML document, please refer to the the original document for copyright information. The author of portaudit makes no claim of authorship or ownership of any of the information contained herein.
If you have found a vulnerability in a FreeBSD port not listed in the database, please contact the FreeBSD Security Team. Refer to "FreeBSD Security Information" for more information.