Tag: privacy

Categories
Papers Publications

new conference paper “Connection-Oriented DNS to Improve Privacy and Security” in Oakland 2015

The paper “Connection-Oriented DNS to Improve Privacy and Security” will appear at the 36th IEEE Symposium on Security and Privacy in May 2015 in San Jose, CA, USA  (available at http://www.isi.edu/~liangzhu/papers/Zhu15b.pdf)

From the abstract:end_to_end_model_n_7

The Domain Name System (DNS) seems ideal for connectionless UDP, yet this choice results in challenges of eavesdropping that compromises privacy, source-address spoofing that simplifies denial-of-service (DoS) attacks on the server and third parties, injection attacks that exploit fragmentation, and reply-size limits that constrain key sizes and policy choices. We propose T-DNS to address these problems. It uses TCP to smoothly support large payloads and to mitigate spoofing and amplification for DoS. T-DNS uses transport-layer security (TLS) to provide privacy from users to their DNS resolvers and optionally to authoritative servers. TCP and TLS are hardly novel, and expectations about DNS suggest connections will balloon client latency and overwhelm server with state. Our contribution is to show that T-DNS significantly improves security and privacy: TCP prevents denial-of-service (DoS) amplification against others, reduces the effects of DoS on the server, and simplifies policy choices about key size. TLS protects against eavesdroppers to the recursive resolver. Our second contribution is to show that with careful implementation choices, these benefits come at only modest cost: end-to-end latency from TLS to the recursive resolver is only about 9% slower when UDP is used to the authoritative server, and 22% slower with TCP to the authoritative. With diverse traces we show that connection reuse can be frequent (60–95% for stub and recursive resolvers, although half that for authoritative servers), and after connection establishment, experiments show that TCP and TLS latency is equivalent to UDP. With conservative timeouts (20 s at authoritative servers and 60 s elsewhere) and estimated per-connection memory, we show that server memory requirements match current hardware: a large recursive resolver may have 24k active connections requiring about 3.6 GB additional RAM. Good performance requires key design and implementation decisions we identify: query pipelining, out-of-order responses, TCP fast-open and TLS connection resumption, and plausible timeouts.

The work in the paper is by Liang Zhu, Zi Hu and John Heidemann (USC/ISI), Duane Wessels and Allison Mankin (both of Verisign Labs), and Nikita Somaiya (USC/ISI).  Earlier versions of this paper were released as ISI-TR-688 and ISI-TR-693; this paper adds results and supercedes that work.

The data in this paper is available to researchers at no cost on request. Please see T-DNS-experiments-20140324 at dataset page.

Categories
Papers Publications

new workshop paper “Privacy Principles for Sharing Cyber Security Data” in IWPE 15

The paper “Privacy Principles for Sharing Cyber Security Data” (available at https://www.isi.edu/~calvin/papers/Fisk15a.pdf) will appear at the International Workshop on Privacy Engineering (co-located with IEEE Symposium on Security and Privacy) on May 21, 2015 in San Jose, California.

From the abstract:

Sharing cyber security data across organizational boundaries brings both privacy risks in the exposure of personal information and data, and organizational risk in disclosing internal information. These risks occur as information leaks in network traffic or logs, and also in queries made across organizations. They are also complicated by the trade-offs in privacy preservation and utility present in anonymization to manage disclosure. In this paper, we define three principles that guide sharing security information across organizations: Least Disclosure, Qualitative Evaluation, and Forward Progress. We then discuss engineering approaches that apply these principles to a distributed security system. Application of these principles can reduce the risk of data exposure and help manage trust requirements for data sharing, helping to meet our goal of balancing privacy, organizational risk, and the ability to better respond to security with shared information.

The work in the paper is by Gina Fisk (LANL), Calvin Ardi (USC/ISI), Neale Pickett (LANL), John Heidemann (USC/ISI), Mike Fisk (LANL), and Christos Papadopoulos (Colorado State). This work is supported by DHS S&T, Cyber Security division.

Categories
Software releases

Digit-1.1 release

Digit-1.1 has been released  (available at https://ant.isi.edu/software/tdns/index.htmlScreenshot from 2014-11-08 16:17:45).  Digit is a DNS client side tool that can perform DNS queries via different protocols such as UDP, TCP, TLS. This tool is primarily designed to evaluate the client side latency of using DNS over TCP/TLS, as described in the technical report “T-DNS: Connection-Oriented DNS to Improve Privacy and Security” (http://www.isi.edu/~johnh/PAPERS/Zhu14b/index.html).

A README in the package has detailed instructions about how to use this software.

Categories
Presentations

new talk “Measuring DANE TLSA Deployment” given at DNS-OARC

Liang Zhu gave the talk “Measuring DANE TLSA Deployment”, given at the Fall DNS-OARC meeting in Los Angeles, California on Oct 12, 2014.  Slides are available: http://www.isi.edu/~liangzhu/presentation/dns-oarc/dane_tlsa_survey.pdf

From the abstract:

The DANE (DNS-based Authentication of Named Entities) framework uses DNSSEC to provide a source of trust, and with TLSA it can serve as a root of trust for TLS certificates. This alternative to traditional certificate authorities is important given the risks inherent in trusting hundreds of organizations—risks already demonstrated with multiple compromises. The TLSA protocol was published in 2012, and this talk presents the first systematic study of its deployment. We studied TLSA usage, developing a tool that actively probes all signed zones in .com and .net for TLSA records. We find the TLSA use is early: in our latest measurement, of the 461k signed zones, we find only 701 TLSA names. We characterize how it is being used so far, and find that around 7–12% of TLSA records are invalid. We find 31% of TLSA responses are larger than 1500 Bytes and get IP fragmented.

The work in the talk is by Liang Zhu (USC/ISI), Duane Wessels and Allison Mankin (both of Verisign), and John Heidemann (USC/ISI).

Categories
Publications Technical Report

new technical report “T-DNS: Connection-Oriented DNS to Improve Privacy and Security (extended)”

We released a new technical report “T-DNS: Connection-Oriented DNS to Improve Privacy and Security (extended)”, ISI-TR-2014-693, available as http://www.isi.edu/~johnh/PAPERS/Zhu14b.pdf

From the abstract:resp_cdf_diff_key_all

DNS is the canonical protocol for connectionless UDP. Yet DNS today is challenged by eavesdropping that compromises privacy, source-address spoofing that results in denial-of-service (DoS) attacks on the server and third parties, injection attacks that exploit fragmentation, and size limitations that constrain policy and operational choices. We propose T-DNS to address these problems. It uses TCP to smoothly support large payloads and to mitigate spoofing and amplification for DoS. T-DNS uses transport-layer security (TLS) to provide privacy from users to their DNS resolvers and optionally to authoritative servers. Expectations about DNS suggest connections will balloon client latency and overwhelm server with state, but our evaluation shows costs are modest: end-to-end latency from TLS to the recursive resolver is only about 9% slower when UDP is used to the authoritative server, and 22% slower with TCP to the authoritative. With diverse traces we show that frequent connection reuse is possible (60–95% for stub and recursive resolvers, although half that for authoritative servers), and after connection establishment, we show TCP and TLS latency is equivalent to UDP. With conservative timeouts (20 s at authoritative servers and 60 s elsewhere) and conservative estimates of connection state memory requirements, we show that server memory requirements match current hardware: a large recursive resolver may have 24k active connections requiring about 3.6 GB additional RAM. We identify the key design and implementation decisions needed to minimize overhead: query pipelining, out-of-order responses, TLS connection resumption, and plausible timeouts.

This paper is a major revision of the prior technical report ISI-TR-2014-688. Since that work we have improved our understanding of the availability of TCP fast open and TLS resumption, and we have tightened our estimates on memory based on external reports (section 5.2). This additional information has allowed us to conduct additional experiments, improve our modeling, and provide a more accurate view of what is possible today; our estimates of latency and memory consumption are both lower than in our prior technical report as a result. We have also added additional information about packet size limitations (Figure 2), experiments evaluating DNSCrypt/DNSCurve (section 6.1), analysis of DTLS, and covered a broader range of RTTs in our experiments. We believe these additions strengthen our central claims: that connectionless DNS causes multiple problems and that T-DNS addresses those problems with modest increase in latency and memory suitable for current hardware.

Categories
Presentations

new talk “T-DNS: Connection-Oriented DNS to Improve Privacy and Security” given at DNS-OARC

John Heidemann gave the talk “T-DNS: Connection-Oriented DNS to Improve Privacy and Security” given at the Spring DNS-OARC meeting in Warsaw, Poland on May 10, 2014.  Slides are available at http://www.isi.edu/~johnh/PAPERS/Heidemann14c.html.

don't fear connections for DNS
don’t fear connections for DNS

From the abstract:

This talk will discuss connection-oriented DNS to improve DNS security and privacy. DNS is the canonical example of a connectionless, single packet, request/response protocol, with UDP as its dominant transport. Yet DNS today is challenged by eavesdropping that compromises privacy, source-address spoofing that results in denial-of-service (DoS) attacks on the server and third parties, injection attacks that exploit fragmentation, and size limitations that constrain policy and operational choices. We propose t-DNS to address these problems: it uses TCP to smoothly support large payloads and mitigate spoofing and amplification for DoS. T-DNS uses transport-layer security (TLS) to provide privacy from users to their DNS resolvers and optionally to authoritative servers.

Traditional wisdom is that connection setup will balloon latency for clients and overwhelm servers. We provide data to show that these assumptions are overblown–our model of end-to-end latency shows TLS to the recursive resolver is only about 5-24% slower, with UDP to the authoritative server. End-to-end latency is 19-33% slower with TLS to recursive and TCP to authoritative. Experiments behind these models show that after connection establishment, TCP and TLS latency is equivalent to UDP. Using diverse trace data we show that frequent connection reuse is possible (60-95% for stub and recursive resolvers, although half that for authoritative servers). With conservative timeouts (20 s at authoritative servers and 60 s elsewhere) we show that : a large recursive resolver may have 25k active connections consuming about 9 GB of RAM. These results depend on specific design and implementation decisions–query pipelining, out-of-order responses, TLS connection resumption, and plausible timeouts.

We hope to solicit feedback from the OARC community about this work to understand design and operational concerns if T-DNS deployment was widespread. The work in the talk is by Liang Zhu, Zi Hu, and John Heidemann (all of USC/ISI), Duane Wessels and Allison Mankin (both of Verisign), and Nikita Somaiya (USC/ISI).

A technical report describing the work is at http://www.isi.edu/ johnh/PAPERS/Zhu14a.pdf and the protocol changes are described ashttp://datatracker.ietf.org/doc/draft-hzhwm-start-tls-for-dns/.

Categories
Publications Technical Report

new technical report “T-DNS: Connection-Oriented DNS to Improve Privacy and Security”

We released a new technical report “T-DNS: Connection-Oriented DNS to Improve Privacy and Security”, ISI-TR-2014-688, available as http://www.isi.edu/~johnh/PAPERS/Zhu14a.pdf

 

From the abstract:sim_hit_server_median_all

This paper explores connection-oriented DNS to improve DNS security and privacy. DNS is the canonical example of a connectionless, single packet, request/response protocol, with UDP as its dominant transport. Yet DNS today is challenged by eavesdropping that compromises privacy, source-address spoofing that results in denial-of-service (DoS) attacks on the server and third parties, injection attacks that exploit fragmentation, and size limitations that constrain policy and operational choices. We propose t-DNS to address these problems: it combines TCP to smoothly support large payloads and mitigate spoofing and amplification for DoS. T-DNS uses transport-layer security (TLS) to provide privacy from users to their DNS resolvers and optionally to authoritative servers. Traditional wisdom is that connection setup will balloon latency for clients and overwhelm servers. These are myths—our model of end-to-end latency shows TLS to the recursive resolver is only about 21% slower, with UDP to the authoritative server. End-to-end latency is 90% slower with TLS to recursive and TCP to authoritative. Experiments behind these models show that after connection establishment, TCP and TLS latency is equivalent to UDP. Using diverse trace data we show that frequent connection reuse is possible (60–95% for stub and recursive resolvers, although half that for authoritative servers). With conservative timeouts (20 s at authoritative servers and 60 s elsewhere) we show that server memory requirements match current hardware: a large recursive resolver may have 25k active connections consuming about 9 GB of RAM. We identify the key design and implementation decisions needed to minimize overhead—query pipelining, out-of-order responses, TLS connection resumption, and plausible timeouts.