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ICANN Continues Collaborative Response to Conficker Worm

The Conficker worm that has infected hosts across the Internet continues to evolve. At this point, we do not believe cause exists for general alarm, but the Internet community must continue to take action against Conficker. ICANN continues to engage in collaborative efforts with security researchers, software & anti-virus vendors and with registries and registrars throughout the DNS community to disseminate information about how the malicious code may seek to leverage the DNS system.

The initial variants of the worm, Conficker A/B, focused on potentially utilizing a limited number of domain names to control the infected computers. The affected registrars have collaborated to block the control of this variant of the worm over the past two months. A new variant, Conficker C, has been identified. This variant is more complex and presents increased mitigation challenges. Among these challenges, Conficker C seeks to use a wider range of domain names across the DNS, involving many more names in across a greater number of registries. Analysis indicates the Conficker C code will become active on April 1st.

ICANN is working with the security, vendor and DNS communities in an effort to proactively inform those involved registries who might be affected with specific information that will enable them to block the use of the DNS to control the infected computers. Through the outreach, the registry community is now in close contact with the Conficker working group and taking actions appropriate to their particular situations. An important note regarding April 1st: While the Conficker C code may become active on this date, the DNS and the Internet will likely not see a sudden wave of disruption or activity from the infected computers. Lack of activity on April 1st does not mean the millions of infected computers have been cleaned up or that efforts to mitigate the control of these computers can stop.

The cooperation to stop the spread of the Conficker worm and block control of the infected computers has become a major effort involving well over 100 organizations. The collaborative has conducted shared technical analysis and passed information resulting in practical, proactive steps to limit control and stop the spread of the worm. ICANN will continue its efforts with the security and DNS communities and sees this effort as a model for effective global response to situations that challenge the security and stability of the Internet and the DNS. We also want to encourage individuals and organizations who are concerned about removing the malicious code and to contribute to disabling Conficker to visit for information regarding what can be done.


    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."