By Dan Campbell
Special to GCN
Network researchers at the National Institute of Standards and
Technology (NIST) have unveiled a method that federal systems
administrators can use to protect their systems from increasingly
complex attacks launched via the Domain Name System (DNS) of the
Internet and private IP networks.
DNS has long been a critical function of the Internet and private IP
networks, but one that tended to operate somewhat incognito. That may be
changing as more complex network attacks targeted at DNS emerge.
In a recently published paper, authors Scott Rose and Anastase Nakassis,
writing under the auspices of NIST and the Homeland Security
Department's Science and Technology Directorate, contend that DNS
security extensions (DNSSEC) originally intended to protect DNS zone
data contain an unintended side effect that facilitates an attack
precursor called zone enumeration.
Attackers use DNSSEC responses to determine the Resource Records (RR) in
a DNS zone, and then launch attacks more quickly against specific hosts
in the zone. The attack potential gets worse when DNS host names give
hints to the content, application or operating system, and consequently
the vulnerabilities, that reside on the hosts. Rose and Nakassis added
that the security or privacy concerns of intercepting information in
newer DNS RRs go beyond an attacker simply identifying the host IP
address and name.
The authors state that zone enumeration is possible without the help of
DNSSEC. They cautioned that such traditional methods often become
impractical because they rely on time-consuming or processor-intensive
brute force techniques often thwarted by intrusion detection systems.
The authors also describe several techniques that allow networks to reap
the intended authentication and integrity benefits of DNSSEC while
reducing DNS information leakage. These techniques are important
because, as DNS becomes more and more vital to network operation, the
need to protect it with techniques offered by DNSSEC increases.
As federal agencies continue to deploy IPv6 technology, DNS will move
from its current critical-but-inconspicuous status to the forefront, the
NIST analysts said. The spread of IPv6 will generate a demand for
network protection methods that are as secure as they are robust. The
enormous IPv6 address size makes memorization impractical and
address-to-hostname mapping vital, Internet specialists agree. Address
subnet scanning becomes all but impossible in the IPv6 environment. As a
result, DNS zone data becomes much more desirable to intercept and
decipher as a prelude to launching an attack.
The techniques described by the NIST scientists likely hold forth the
promise of improving DNSSEC authentication and integrity protection, so
as to shield DNS zones and foil attempts to compromise data.
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