--- 1/draft-ietf-dprive-problem-statement-01.txt 2015-02-19 08:15:01.978632791 -0800 +++ 2/draft-ietf-dprive-problem-statement-02.txt 2015-02-19 08:15:02.018633765 -0800 @@ -1,45 +1,44 @@ DNS PRIVate Exchange (dprive) Working Group S. Bortzmeyer Internet-Draft AFNIC -Intended status: Informational January 7, 2015 -Expires: July 11, 2015 +Intended status: Informational February 19, 2015 +Expires: August 23, 2015 DNS privacy considerations - draft-ietf-dprive-problem-statement-01 + draft-ietf-dprive-problem-statement-02 Abstract This document describes the privacy issues associated with the use of - the DNS by Internet users. It is intended to be mostly an analysis - of the present situation, in the spirit of section 8 of [RFC6973] and - it does not prescribe solutions. + the DNS by Internet users. It is intended to be an analysis of the + present situation and does not prescribe solutions. Discussions of the document should take place on the DPRIVE working group mailing list [dprive]. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on July 11, 2015. + This Internet-Draft will expire on August 23, 2015. Copyright Notice Copyright (c) 2015 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents @@ -50,137 +49,144 @@ described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Risks . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1. The alleged public nature of DNS data . . . . . . . . . . 4 2.2. Data in the DNS request . . . . . . . . . . . . . . . . . 5 2.3. Cache snooping . . . . . . . . . . . . . . . . . . . . . 6 2.4. On the wire . . . . . . . . . . . . . . . . . . . . . . . 6 - 2.5. In the servers . . . . . . . . . . . . . . . . . . . . . 7 + 2.5. In the servers . . . . . . . . . . . . . . . . . . . . . 8 2.5.1. In the recursive resolvers . . . . . . . . . . . . . 8 2.5.2. In the authoritative name servers . . . . . . . . . . 8 - 2.5.3. Rogue servers . . . . . . . . . . . . . . . . . . . . 9 + 2.5.3. Rogue servers . . . . . . . . . . . . . . . . . . . . 10 3. Actual "attacks" . . . . . . . . . . . . . . . . . . . . . . 10 4. Legalities . . . . . . . . . . . . . . . . . . . . . . . . . 10 - 5. Security considerations . . . . . . . . . . . . . . . . . . . 10 - 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10 - 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 - 7.1. Normative References . . . . . . . . . . . . . . . . . . 11 - 7.2. Informative References . . . . . . . . . . . . . . . . . 11 - 7.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 14 - Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 14 + 5. Security considerations . . . . . . . . . . . . . . . . . . . 11 + 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11 + 7. IANA considerations . . . . . . . . . . . . . . . . . . . . . 11 + 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 + 8.1. Normative References . . . . . . . . . . . . . . . . . . 11 + 8.2. Informative References . . . . . . . . . . . . . . . . . 12 + 8.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 15 + Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 15 1. Introduction + This document is an analysis of the DNS privacy issues, in the spirit + of section 8 of [RFC6973]. + The Domain Name System is specified in [RFC1034] and [RFC1035]. It is one of the most important infrastructure components of the - Internet and one of the most often ignored or misunderstood. Almost - every activity on the Internet starts with a DNS query (and often - several). Its use has many privacy implications and we try to give - here a comprehensive and accurate list. + Internet and often ignored or misunderstood. Almost every activity + on the Internet starts with a DNS query (and often several). Its use + has many privacy implications and this is an attempt at a + comprehensive and accurate list. Let us begin with a simplified reminder of how the DNS works. (REMOVE BEFORE PUBLICATION: We hope that the document [I-D.hoffman-dns-terminology] will be published as a RFC so most of this section could be replaced by a reference to it.) A client, the - stub resolver, issues a DNS query to a server, the recursive resolver - (also called caching resolver or full resolver or simply resolver - recursive name server). Let's use the query "What are the AAAA - records for www.example.com?" as an example. AAAA is the qtype - (Query type), and www.example.com is the qname (Query Name). The - recursive resolver will first query the root nameservers. In most - cases, the root nameservers will send a referral. In this example, - the referral will be to .com nameservers. The resolver repeats the - query to one of the .com nameservers. The .com nameserver, in turn, - will refer to the example.com nameservers. The example.com - nameserver will then return the answer. The root name servers, the - name servers of .com and those of example.com are called - authoritative name servers. It is important, when analyzing the - privacy issues, to remember that the question asked to all these name - servers is always the original question, not a derived question. - Unlike what many "DNS for dummies" articles say, the question sent to + stub resolver, issues a DNS query to a server, called the recursive + resolver (also called caching resolver or full resolver or recursive + name server). Let's use the query "What are the AAAA records for + www.example.com?" as an example. AAAA is the qtype (Query Type), and + www.example.com is the qname (Query Name). The recursive resolver + will first query the root nameservers. In most cases, the root + nameservers will send a referral. In this example, the referral will + be to the .com nameservers. The resolver repeats the query to one of + the .com nameservers. The .com nameservers, in turn, will refer to + the example.com nameservers. The example.com nameserver will then + return the answer. The root name servers, the name servers of .com + and the name servers of example.com are called authoritative name + servers. It is important, when analyzing the privacy issues, to + remember that the question asked to all these name servers is always + the original question, not a derived question. The question sent to the root name servers is "What are the AAAA records for www.example.com?", not "What are the name servers of .com?". By repeating the full question, instead of just the relevant part of the question to the next in line, the DNS provides more information than necessary to the nameserver. - Because the DNS uses caching heavily, not all questions are sent to - the authoritative name servers. If the stub resolver, a few seconds - later, asks to the recursive resolver "What are the SRV records of + Because DNS relies on caching heavily, not all questions are sent to + the authoritative name servers. If a few seconds later the stub + resolver asks to the recursive resolver, "What are the SRV records of _xmpp-server._tcp.example.com?", the recursive resolver will remember that it knows the name servers of example.com and will just query them, bypassing the root and .com. Because there is typically no caching in the stub resolver, the recursive resolver, unlike the - authoritative servers, sees everything. + authoritative servers, sees all the DNS traffic. (Applications, like + Web browsers, may have some form of caching, which do not follow DNS + rules. So, the recursive resolver does not see all the name + resolution activity.) It should be noted that DNS recursive resolvers sometimes forward - requests to bigger machines, with a larger and more shared cache, the - forwarders (and the query hierarchy can be even deeper, with more - than two levels of recursive resolvers). From the point of view of - privacy, forwarders are like resolvers, except that the caching in - the recursive resolvers before them decreases the amount of data they - can see. + requests to other recursive resolvers, typically bigger machines, + with a larger and more shared cache (and the query hierarchy can be + even deeper, with more than two levels of recursive resolvers). From + the point of view of privacy, these forwarders are like resolvers, + except that they do not see all of the requests being made (due to + caching in the first resolver). - All this DNS traffic is today sent in clear (unencryted), except a - few cases when the IP traffic is protected, for instance in an IPsec - VPN. + All this DNS traffic is currently sent in clear (unencryted), except + a few cases when the IP traffic is protected, for instance in an + IPsec VPN. Today, almost all DNS queries are sent over UDP. This has practical - consequences, when considering a possible privacy technique, - encryption of the traffic: some encryption solutions are only - designed for TCP, not UDP. + consequences when considering encryption of the traffic as a possible + privacy technique. Some encryption solutions are only designed for + TCP, not UDP. Another important point to keep in mind when analyzing the privacy issues of DNS is the mix of many sort of DNS requests received by a - server. Let's assume the eavesdropper wants to know which Web page - is viewed by an user. For a typical Web page displayed by the user, - there are three sorts of DNS requests being issued: + server. Let's assume an eavesdropper wants to know which Web page is + viewed by an user. For a typical Web page, there are three sorts of + DNS requests being issued: Primary request: this is the domain name in the URL that the user - typed or selected from a bookmark or choose by clicking on an + typed, selected from a bookmark or chose by clicking on an hyperlink. Presumably, this is what is of interest for the eavesdropper. Secondary requests: these are the additional requests performed by the user agent (here, the Web browser) without any direct involvement or knowledge of the user. For the Web, they are triggered by embedded content, CSS sheets, JavaScript code, embedded images, etc. In some cases, there can be dozens of domain names in different contexts on a single Web page. Tertiary requests: these are the additional requests performed by the DNS system itself. For instance, if the answer to a query is - a referral to a set of name servers, and the glue is not returned, - the resolver will have to do tertiary requests to turn name - servers' names into IP addresses. Similarly, even if glue records - are returned, a careful recursive server will do tertiary requests - to verify the IP addresses of those records. + a referral to a set of name servers, and the glue records are not + returned, the resolver will have to do additional requests to turn + name servers' names into IP addresses. Similarly, even if glue + records are returned, a careful recursive server will do tertiary + requests to verify the IP addresses of those records. It can be noted also that, in the case of a typical Web browser, more DNS requests are sent, for instance to prefetch resources that the user may query later, or when autocompleting the URL in the address bar (which obviously is a big privacy concern). For privacy-related terms, we will use here the terminology of [RFC6973]. 2. Risks This document focuses mostly on the study of privacy risks for the end-user (the one performing DNS requests). We consider the risks of - pervasive surveillance ([RFC7258]) and also risks coming from a more - focused surveillance. Privacy risks for the holder of a zone (the - risk that someone gets the data) are discussed in [RFC5936]. Non- - privacy risks (such as cache poisoning) are out of scope. + pervasive surveillance ([RFC7258]) as well as risks coming from a + more focused surveillance. Privacy risks for the holder of a zone + (the risk that someone gets the data) are discussed in [RFC5936] and + [RFC5155]. Non-privacy risks (such as cache poisoning) are out of + scope. 2.1. The alleged public nature of DNS data It has long been claimed that "the data in the DNS is public". While this sentence makes sense for an Internet-wide lookup system, there are multiple facets to the data and metadata involved that deserve a more detailed look. First, access control lists and private namespaces nonwithstanding, the DNS operates under the assumption that public facing authoritative name servers will respond to "usual" DNS queries for any zone they are authoritative for without further @@ -198,25 +204,25 @@ described above, and may not have any confidentiality requirements. However, the same is not true of a single transaction or sequence of transactions; that transaction is not/should not be public. A typical example from outside the DNS world is: the Web site of Alcoholics Anonymous is public; the fact that you visit it should not be. 2.2. Data in the DNS request The DNS request includes many fields but two of them seem - particularly relevant for the privacy issues, the qname and the + particularly relevant for the privacy issues: the qname and the source IP address. "source IP address" is used in a loose sense of "source IP address + maybe source port", because the port is also in the request and can be used to sort out several users sharing an IP - address (behind a CGN for instance). + address (behind a CGN for instance [RFC6269]). The qname is the full name sent by the user. It gives information about what the user does ("What are the MX records of example.net?" means he probably wants to send email to someone at example.net, which may be a domain used by only a few persons and therefore very revealing about communication relationships). Some qnames are more sensitive than others. For instance, querying the A record of google-analytics.com reveals very little (everybody visits Web sites which use Google Analytics) but querying the A record of www.verybad.example where verybad.example is the domain of an illegal @@ -238,30 +244,30 @@ For the communication between the stub resolver and the recursive resolver, the source IP address is the address of the user's machine. Therefore, all the issues and warnings about collection of IP addresses apply here. For the communication between the recursive resolver and the authoritative name servers, the source IP address has a different meaning; it does not have the same status as the source address in a HTTP connection. It is now the IP address of the recursive resolver which, in a way "hides" the real user. However, hiding does not always work. Sometimes - [I-D.vandergaast-edns-client-subnet] is used (see its privacy - analysis in [denis-edns-client-subnet]). Sometimes the end user has - a personal recursive resolver on her machine. In both cases, the IP + [I-D.ietf-dnsop-edns-client-subnet] is used (see its privacy analysis + in [denis-edns-client-subnet]). Sometimes the end user has a + personal recursive resolver on her machine. In both cases, the IP address is as sensitive as it is for HTTP. A note about IP addresses: there is currently no IETF document which - describes in detail the privacy issues of IP addressing. In the - meantime, the discussion here is intended to include both IPv4 and - IPv6 source addresses. For a number of reasons their assignment and - utilization characteristics are different, which may have + describes in detail all the privacy issues around IP addressing. In + the meantime, the discussion here is intended to include both IPv4 + and IPv6 source addresses. For a number of reasons their assignment + and utilization characteristics are different, which may have implications for details of information leakage associated with the collection of source addresses. (For example, a specific IPv6 source address seen on the public Internet is less likely than an IPv4 address to originate behind a CGN or other NAT.) However, for both IPv4 and IPv6 addresses, it's important to note that source addresses are propagated with queries and comprise metadata about the host, user, or application that originated them. 2.3. Cache snooping @@ -345,25 +351,27 @@ start collecting data. Many programs exist to collect and analyze DNS data at the servers. From the "query log" of some programs like BIND, to tcpdump and more sophisticated programs like PacketQ [packetq] and DNSmezzo [dnsmezzo]. The organization managing the DNS server can use these data itself or it can be part of a surveillance program like PRISM [prism] and pass data to an outside observer. Sometimes, these data are kept for a long time and/or distributed to - third parties, for research purposes [ditl], for security analysis, - or for surveillance tasks. Also, there are observation points in the - network which gather DNS data and then make it accessible to third- - parties for research or security purposes ("passive DNS - [passive-dns]"). + third parties, for research purposes [ditl] [day-at-root], for + security analysis, or for surveillance tasks. These uses are + sometimes under some sort of contract, with various limitations, for + instance on redistribution, giving the sensitive nature of the data. + Also, there are observation points in the network which gather DNS + data and then make it accessible to third-parties for research or + security purposes ("passive DNS [passive-dns]"). 2.5.1. In the recursive resolvers Recursive Resolvers see all the traffic since there is typically no caching before them. To summarize: your recursive resolver knows a lot about you. The resolver of a large IAP, or a large public resolver can collect data from many users. You may get an idea of the data collected by reading the privacy policy of a big public resolver [1]. @@ -377,187 +385,219 @@ everything. Still, the authoritative name servers see a part of the traffic, and this subset may be sufficient to violate some privacy expectations. Also, the end user has typically some legal/contractual link with the recursive resolver (he has chosen the IAP, or he has chosen to use a given public resolver), while having no control and perhaps no awareness of the role of the authoritative name servers and their observation abilities. - It is an interesting question whether the privacy issues are bigger - in the root or in a large TLD. The root sees the traffic for all the - TLDs (and the huge amount of traffic for non-existing TLDs), but a - large TLDs has less caching before it. - As noted before, using a local resolver or a resolver close to the machine decreases the attack surface for an on-the-wire eavesdropper. But it may decrease privacy against an observer located on an authoritative name server. This authoritative name server will see the IP address of the end client, instead of the address of a big recursive resolver shared by many users. This "protection", when using a large resolver with many clients, is - no longer present if [I-D.vandergaast-edns-client-subnet] is used + no longer present if [I-D.ietf-dnsop-edns-client-subnet] is used because, in this case, the authoritative name server sees the original IP address (or prefix, depending on the setup). As of today, all the instances of one root name server, L-root, receive together around 20,000 queries per second. While most of it is junk (errors on the TLD name), it gives an idea of the amount of big data which pours into name servers. Many domains, including TLDs, are partially hosted by third-party servers, sometimes in a different country. The contracts between the domain manager and these servers may or may not take privacy into account. Whatever the contract, the third-party hoster may be honest or not but, in any case, it will have to follow its local laws. It may be surprising for an end-user that requests to a given ccTLD may go to servers managed by organisations outside of the country. - Also, it seems (TODO: actual numbers requested) that there is a - strong concentration of authoritative name servers among "popular" - domains (such as the Alexa Top N list). With the control (or the - ability to sniff the traffic) of a few name servers, you can gather a - lot of information. + Also, it seems [aeris-dns] that there is a strong concentration of + authoritative name servers among "popular" domains (such as the Alexa + Top N list). For instance, among the Alexa Top 100k, one DNS + provider hosts today 10 % of the domains. The ten most important DNS + providers host together one third of the domains. With the control + (or the ability to sniff the traffic) of a few name servers, you can + gather a lot of information. 2.5.3. Rogue servers A rogue DHCP server, or a trusted DHCP server that has had its configuration altered by malicious parties, can direct you to a rogue - recursive resolver. Most of the times, it seems to be done to divert + recursive resolver. Most of the time, it seems to be done to divert traffic, by providing lies for some domain names. But it could be used just to capture the traffic and gather information about you. Same thing for malware like DNSchanger[dnschanger] which changes the recursive resolver in the machine's configuration, or with transparent DNS proxies in the network that will divert the traffic intended for a legitimate DNS server (for instance [turkey-googledns]). 3. Actual "attacks" A very quick examination of DNS traffic may lead to the false conclusion that extracting the needle from the haystack is difficult. "Interesting" primary DNS requests are mixed with useless (for the - eavesdropper) second and tertiary requests (see the terminology in + eavesdropper) secondary and tertiary requests (see the terminology in Section 1). But, in this time of "big data" processing, powerful - techniques now exist to get from the raw data to what you're actually - interested in. + techniques now exist to get from the raw data to what the + eavesdropper is actually interested in. Many research papers about malware detection use DNS traffic to detect "abnormal" behaviour that can be traced back to the activity of malware on infected machines. Yes, this research was done for the - good but, technically, it is a privacy attack and it demonstrates the - power of the observation of DNS traffic. See [dns-footprint], + good; but, technically, it is a privacy attack and it demonstrates + the power of the observation of DNS traffic. See [dns-footprint], [dagon-malware] and [darkreading-dns]. Passive DNS systems [passive-dns] allow reconstruction of the data of - sometimes an entire zone. It is used for many reasons, some good, - some bad. It is an example of a privacy issue even when no source IP - address is kept. + sometimes an entire zone. They are used for many reasons, some good, + some bad. Well-known passive DNS systems keep only the DNS + responses, and not the source IP address of the client, precisely for + privacy reasons. Other passive DNS systems may not be so careful. + And there is still the potential problems with revealing qnames. + + The revelations (from the Edward Snowden documents, leaked from the + NSA) of the MORECOWBELL surveillance program [morecowbell], which + uses the DNS, both passively and actively, to gather surreptitiously + information about the users, is another good example that the lack of + privacy protections in the DNS is actively exploited. 4. Legalities To our knowledge, there are no specific privacy laws for DNS data. Interpreting general privacy laws like [data-protection-directive] (European Union) in the context of DNS traffic data is not an easy task and it seems there is no court precedent here. 5. Security considerations This document is entirely about security, more precisely privacy. It - just lays down the problem, it does not try to set requirments (with + just lays out the problem, it does not try to set requirments (with the choices and compromises they imply), much less to define - solutions. A document on requirments for DNS privacy is + solutions. A possible document on requirments for DNS privacy is [I-D.hallambaker-dnse]. Possible solutions to the issues described - here are discussed in other documents (currently too many to be - listed here). + here are discussed in other documents (currently too many to all be + mentioned), see for instance [I-D.ietf-dnsop-qname-minimisation] for + the minimisation of data, or [I-D.hzhwm-start-tls-for-dns] about + encryption. 6. Acknowledgments Thanks to Nathalie Boulvard and to the CENTR members for the original work which leaded to this document. Thanks to Ondrej Sury for the interesting discussions. Thanks to Mohsen Souissi and John Heidemann - for proofreading, to Paul Hoffman, Marcos Sanz and Warren Kumari for - proofreading, technical remarks, and many readability improvements. - Thanks to Dan York, Suzanne Woolf, Tony Finch, Peter Koch and Frank - Denis for good written contributions. + for proofreading, to Paul Hoffman, Marcos Sanz, Tim Wicinski, Allison + Mankin and Warren Kumari for proofreading, technical remarks, and + many readability improvements. Thanks to Dan York, Suzanne Woolf, + Tony Finch, Peter Koch and Frank Denis for good written + contributions. -7. References +7. IANA considerations -7.1. Normative References + This document has no actions for IANA. + +8. References + +8.1. Normative References [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", STD 13, RFC 1034, November 1987. [RFC1035] Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, November 1987. - [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate - Requirement Levels", BCP 14, RFC 2119, March 1997. - [RFC6973] Cooper, A., Tschofenig, H., Aboba, B., Peterson, J., Morris, J., Hansen, M., and R. Smith, "Privacy Considerations for Internet Protocols", RFC 6973, July 2013. [RFC7258] Farrell, S. and H. Tschofenig, "Pervasive Monitoring Is an Attack", BCP 188, RFC 7258, May 2014. -7.2. Informative References +8.2. Informative References [RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, "DNS Security Introduction and Requirements", RFC 4033, March 2005. + [RFC5155] Laurie, B., Sisson, G., Arends, R., and D. Blacka, "DNS + Security (DNSSEC) Hashed Authenticated Denial of + Existence", RFC 5155, March 2008. + [RFC5936] Lewis, E. and A. Hoenes, "DNS Zone Transfer Protocol (AXFR)", RFC 5936, June 2010. - [I-D.vandergaast-edns-client-subnet] - Contavalli, C., Gaast, W., Leach, S., and E. Lewis, - "Client Subnet in DNS Requests", draft-vandergaast-edns- - client-subnet-02 (work in progress), July 2013. + [RFC6269] Ford, M., Boucadair, M., Durand, A., Levis, P., and P. + Roberts, "Issues with IP Address Sharing", RFC 6269, June + 2011. + + [I-D.ietf-dnsop-edns-client-subnet] + Contavalli, C., Gaast, W., Lawrence, D., and W. Kumari, + "Client Subnet in DNS Requests", draft-ietf-dnsop-edns- + client-subnet-00 (work in progress), November 2014. [I-D.hallambaker-dnse] Hallam-Baker, P., "DNS Privacy and Censorship: Use Cases - and Requirements.", draft-hallambaker-dnse-01 (work in - progress), May 2014. + and Requirements.", draft-hallambaker-dnse-02 (work in + progress), November 2014. [I-D.wouters-dane-openpgp] Wouters, P., "Using DANE to Associate OpenPGP public keys with email addresses", draft-wouters-dane-openpgp-02 (work in progress), February 2014. + [I-D.hzhwm-start-tls-for-dns] + Zi, Z., Zhu, L., Heidemann, J., Mankin, A., and D. + Wessels, "Starting TLS over DNS", draft-hzhwm-start-tls- + for-dns-01 (work in progress), July 2014. + + [I-D.ietf-dnsop-qname-minimisation] + Bortzmeyer, S., "DNS query name minimisation to improve + privacy", draft-ietf-dnsop-qname-minimisation-01 (work in + progress), February 2015. + [I-D.hoffman-dns-terminology] Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS - Terminology", draft-hoffman-dns-terminology-00 (work in - progress), November 2014. + Terminology", draft-hoffman-dns-terminology-01 (work in + progress), January 2015. [dprive] IETF, DPRIVE., "The DPRIVE working group", March 2014, . [denis-edns-client-subnet] Denis, F., "Security and privacy issues of edns-client- subnet", August 2013, . [dagon-malware] Dagon, D., "Corrupted DNS Resolution Paths: The Rise of a Malicious Resolution Authority", 2007, . [dns-footprint] Stoner, E., "DNS footprint of malware", October 2010, . + [morecowbell] + Grothoff, C., Wachs, M., Ermert, M., and J. Appelbaum, + "NSA's MORECOWBELL: Knell for DNS", January 2015, + . + [darkreading-dns] Lemos, R., "Got Malware? Three Signs Revealed In DNS Traffic", May 2013, . [dnschanger] Wikipedia, , "DNSchanger", November 2011, . @@ -568,20 +608,26 @@ [dnsmezzo] Bortzmeyer, S., "DNSmezzo", 2009, . [prism] NSA, , "PRISM", 2007, . [ditl] CAIDA, , "A Day in the Life of the Internet (DITL)", 2002, . + [day-at-root] + Castro, S., Wessels, D., Fomenkov, M., and K. Claffy, "A + Day at the Root of the Internet", 2008, + . + [turkey-googledns] Bortzmeyer, S., "Hijacking of public DNS servers in Turkey, through routing", 2014, . [data-protection-directive] Europe, , "European directive 95/46/EC on the protection of individuals with regard to the processing of personal data and on the free movement of such data", November @@ -613,21 +659,26 @@ Disclosure in DNS Query", 2007, . [federrath-fuchs-herrmann-piosecny] Federrath, H., Fuchs, K., Herrmann, D., and C. Piosecny, "Privacy-Preserving DNS: Analysis of Broadcast, Range Queries and Mix-Based Protection Methods", 2011, . -7.3. URIs + [aeris-dns] + Vinot, N., "[In French] Vie privee : et le DNS alors ?", + 2015, . + +8.3. URIs [1] https://developers.google.com/speed/public-dns/privacy Author's Address Stephane Bortzmeyer AFNIC 1, rue Stephenson Montigny-le-Bretonneux 78180 France