NIST Unveils Tool To Foil DNS Attacks
- By Dan Campbell
Network researchers at the National Institute of Standards and Technology have unveiled a method that federal systems administrators can use to protect
their systems from increasingly complex attacks launched via the Domain Name
System 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 potentially 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.