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Conflicker, DNS Security and what ICANN is doing about it

Over the past two months the Internet has faced yet another threat to its security and one that directly involves the Domain Name System.

The Conflicker/Downadup worm infects computers running Windows operating systems variants. The infected computers can be remotely controlled (i.e. forming a botnet) and the infection propagates through a number of different routes. The worm has been estimated as infecting as many as 10 million hosts and data from the security community indicates the number is at least 1.5 million. One mechanism the worm’s code uses to enable control is to download commands by accessing specific date-based domain names.

In mid-January, security community researchers began to understand which future domain names that the botnet would seek to utilize. These researchers sought cooperation from these registries to protect the names that would potentially be utilized. ICANN has worked with the registries, the security researcher community and Microsoft to share information, discuss specific mitigation steps and reach out globally across all involved parties to block the spread of the worm and formation of a massive botnet. This type of collaborative response is a model for dealing with distributed, evolving threats to the Internet’s security and resiliency.

We believe that malicious code using the DNS to enable propagation of worms and establishment of large botnets is likely to continue, even increase, in the short term. We are continuing our collaboration in response to the Conflicker/Downadup worm/botnet. DNS registries, the security community, and ICANN staff have agreed to initiate a working group to establish how ICANN can enable timely and effective responses to such worm/botnet situations that involve abuse of the DNS and threaten Internet security and resiliency.

Greg Rattray

ICANN Chief Internet Security Advisor


    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."