the patch from ISC for lib/bind9/check.c and deletion of unused
files in lib/bind.
This version will by default randomize the UDP query source port
(and sequence number of course) for every query.
In order to take advantage of this randomization users MUST have an
appropriate firewall configuration to allow UDP queries to be sent and
answers to be received on random ports; and users MUST NOT specify a
port number using the query-source[-v6] options.
The avoid-v[46]-udp-ports options exist for users who wish to eliminate
certain port numbers from being chosen by named for this purpose. See
the ARM Chatper 6 for more information.
Also please note, this issue applies only to UDP query ports. A random
ephemeral port is always chosen for TCP queries.
This issue applies primarily to name servers whose main purpose is to
resolve random queries (sometimes referred to as "caching" servers, or
more properly as "resolving" servers), although even an "authoritative"
name server will make some queries, primarily at startup time.
All users of BIND are strongly encouraged to upgrade to the latest
version, and to utilize the source port randomization feature.
This update addresses issues raised in:
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-1447http://www.kb.cert.org/vuls/id/800113http://tools.ietf.org/html/draft-ietf-dnsext-forgery-resilience
1. The default access control lists (acls) are not being
correctly set. If not set anyone can make recursive queries
and/or query the cache contents.
See also:
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-2925
2. The DNS query id generation is vulnerable to cryptographic
analysis which provides a 1 in 8 chance of guessing the next
query id for 50% of the query ids. This can be used to perform
cache poisoning by an attacker.
This bug only affects outgoing queries, generated by BIND 9 to
answer questions as a resolver, or when it is looking up data
for internal uses, such as when sending NOTIFYs to slave name
servers.
All users are encouraged to upgrade.
See also:
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-2926
Approved by: re (kensmith, implicit)
announced by ISC dated 31 October (delivered via e-mail to the
bind-announce@isc.org list on 2 November):
Description:
Because of OpenSSL's recently announced vulnerabilities
(CAN-2006-4339, CVE-2006-2937 and CVE-2006-2940) which affect named,
we are announcing this workaround and releasing patches. A proof of
concept attack on OpenSSL has been demonstrated for CAN-2006-4339.
OpenSSL is required to use DNSSEC with BIND.
Fix for version 9.3.2-P1 and lower:
Upgrade to BIND 9.3.2-P2, then generate new RSASHA1 and
RSAMD5 keys for all old keys using the old default exponent
and perform a key rollover to these new keys.
These versions also change the default RSA exponent to be
65537 which is not vulnerable to the attacks described in
CAN-2006-4339.
