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Response to Recent Security Threats

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ICANN has been the recent target of online attacks. This announcement provides more information on those attacks and ICANN's response to them.

As has been widely reported, a number of domain names, including and were recently redirected to different DNS servers, allowing a group to provide visitors to those domains with their own website.

The domains in question are used only as mirrors for ICANN and IANA's main websites. The organizations' actual websites at and were unaffected.

The DNS redirect was a result of an attack on ICANN's registrar's systems. A full, confidential, security report from that registrar has since been provided to ICANN with respect to this attack.

It would appear the attack was sophisticated, combining both social and technological techniques, but was also limited and focused. The redirect was noticed and corrected within 20 minutes; however it may have taken anywhere up to 48 hours for the redirect to be entirely removed from the Internet.

ICANN is confident that the lessons learned and new security measures since introduced will ensure there is not a repeat of this situation in future. ICANN's Security and Stability Advisory Committee (SSAC) is considering the issue of access to domain names through registrars as a priority research topic. The results of that work will be made available through the usual channels.

In a separate and unrelated incident a few days later, attackers used a very recent exploit in popular blogging software Wordpress to target the ICANN blog. The attack was noticed immediately and the blog taken offline while an analysis was run. That analysis pointed to an automated attack. The blogging software has since been patched and no wider impact (except the disappearance of the blog while the analysis was carried out) was noted.

In response to the attacks, ICANN has started an internal review of its existing security procedures to see if there are any lessons that can be learnt and to make any improvements necessary. Full reports on both incidents have been provided to law enforcement agencies.

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Domain Name System
Internationalized Domain Name ,IDN,"IDNs are domain names that include characters used in the local representation of languages that are not written with the twenty-six letters of the basic Latin alphabet ""a-z"". An IDN can contain Latin letters with diacritical marks, as required by many European languages, or may consist of characters from non-Latin scripts such as Arabic or Chinese. Many languages also use other types of digits than the European ""0-9"". The basic Latin alphabet together with the European-Arabic digits are, for the purpose of domain names, termed ""ASCII characters"" (ASCII = American Standard Code for Information Interchange). These are also included in the broader range of ""Unicode characters"" that provides the basis for IDNs. The ""hostname rule"" requires that all domain names of the type under consideration here are stored in the DNS using only the ASCII characters listed above, with the one further addition of the hyphen ""-"". The Unicode form of an IDN therefore requires special encoding before it is entered into the DNS. The following terminology is used when distinguishing between these forms: A domain name consists of a series of ""labels"" (separated by ""dots""). The ASCII form of an IDN label is termed an ""A-label"". All operations defined in the DNS protocol use A-labels exclusively. The Unicode form, which a user expects to be displayed, is termed a ""U-label"". The difference may be illustrated with the Hindi word for ""test"" — परीका — appearing here as a U-label would (in the Devanagari script). A special form of ""ASCII compatible encoding"" (abbreviated ACE) is applied to this to produce the corresponding A-label: xn--11b5bs1di. A domain name that only includes ASCII letters, digits, and hyphens is termed an ""LDH label"". Although the definitions of A-labels and LDH-labels overlap, a name consisting exclusively of LDH labels, such as"""" is not an IDN."