Categories
Announcements Students

congratulations to Liang Zhu for his new PhD

I would like to congratulate Dr. Liang Zhu for defending his PhD in August 2018 and completing his doctoral dissertation “Balancing Security and Performance of Network Request-Response Protocols” in September 2018.

Liang Zhu (left) and John Heidemann, after Liang’s PhD defense.

From the abstract:

The Internet has become a popular tool to acquire information and knowledge. Usually information retrieval on the Internet depends on request-response protocols, where clients and servers exchange data. Despite of their wide use, request-response protocols bring challenges for security and privacy. For example, source-address spoofing enables denial-of-service (DoS) attacks, and eavesdropping of unencrypted data leaks sensitive information in request-response protocols. There is often a trade-off between security and performance in request-response protocols. More advanced protocols, such as Transport Layer Security (TLS), are proposed to solve these problems of source spoofing and eavesdropping. However, developers often avoid adopting those advanced protocols, due to performance costs such as client latency and server memory requirement. We need to understand the trade-off between security and performance for request-response protocols and find a reasonable balance, instead of blindly prioritizing one of them.
This thesis of this dissertation states that it is possible to improve security of network request-response protocols without compromising performance, by protocol and deployment optimizations, that are demonstrated through measurements of protocol developments and deployments. We support the thesis statement through three specific studies, each of which uses measurements and experiments to evaluate the development and optimization of a request-response protocol. We show that security benefits can be achieved with modest performance costs. In the first study, we measure the latency of OCSP in TLS connections. We show that OCSP has low latency due to its wide use of CDN and caching, while identifying certificate revocation to secure TLS. In the second study, we propose to use TCP and TLS for DNS to solve a range of fundamental problems in DNS security and privacy. We show that DNS over TCP and TLS can achieve favorable performance with selective optimization. In the third study, we build a configurable, general-purpose DNS trace replay system that emulates global DNS hierarchy in a testbed and enables DNS experiments at scale efficiently. We use this system to further prove the reasonable performance of DNS over TCP and TLS at scale in the real world.

In addition to supporting our thesis, our studies have their own research contributions. Specifically, In the first work, we conducted new measurements of OCSP by examining network traffic of OCSP and showed a significant improvement of OCSP latency: a median latency of only 20ms, much less than the 291ms observed in prior work. We showed that CDN serves 94% of the OCSP traffic and OCSP use is ubiquitous. In the second work, we selected necessary protocol and implementation optimizations for DNS over TCP/TLS, and suggested how to run a production TCP/TLS DNS server [RFC7858]. We suggested appropriate connection timeouts for DNS operations: 20s at authoritative servers and 60s elsewhere. We showed that the cost of DNS over TCP/TLS can be modest. Our trace analysis showed that connection reuse can be frequent (60%-95% for stub and recursive resolvers). We showed that server memory is manageable (additional 3.6GB for a recursive server), and latency of connection-oriented DNS is acceptable (9%-22% slower than UDP). In the third work, we showed how to build a DNS experimentation framework that can scale to emulate a large DNS hierarchy and replay large traces. We used this experimentation framework to explore how traffic volume changes (increasing by 31%) when all DNS queries employ DNSSEC. Our DNS experimentation framework can benefit other studies on DNS performance evaluations.

Categories
DNS Papers Presentations Publications

New paper and talk “Enumerating Privacy Leaks in DNS Data Collected above the Recursive” at NDSS DNS Privacy Workshop 2018

Basileal Imana presented the paper “Enumerating Privacy Leaks in DNS Data Collected  above the Recursive” at NDSS DNS Privacy Workshop in San Diego, California, USA on February 18, 2018. Talk slides are available at https://ant.isi.edu/~imana/presentations/Imana18b.pdf and paper is available at  https://ant.isi.edu/~imana/papers/Imana18a.pdf, or can be found at the DNS privacy workshop page.

From the abstract:

Threat model for enumerating leaks above the recursive (left). Percentage of four categories of queries containing IPv4 addresses in their QNAMEs. (right)

As with any information system consisting of data derived from people’s actions, DNS data is vulnerable to privacy risks. In DNS, users make queries through recursive resolvers to authoritative servers. Data collected below (or in) the recursive resolver directly exposes users, so most prior DNS data sharing focuses on queries above the recursive resolver. Data collected above a recursive resolver has largely been seen as posing a minimal privacy risk since recursive resolvers typically aggregate traffic for many users, thereby hiding their identity and mixing their traffic. Although this assumption is widely made, to our knowledge it has not been verified. In this paper we re-examine this assumption for DNS traffic above the recursive resolver. First, we show that two kinds of information appear in query names above the recursive resolver: IP addresses and sensitive domain names, such as those pertaining to health, politics, or personal or lifestyle information. Second, we examine how often these classes of potentially sensitive names appear in Root DNS traffic, using 48 hours of B-Root data from April 2017.

This is a joint work by Basileal Imana (USC), Aleksandra Korolova (USC) and John Heidemann (USC/ISI).

The DITL dataset (ITL_B_Root-20170411) used in this work is available from DHS IMPACT, the ANT project, and through DNS-OARC.

Categories
Announcements In-the-news

new RFC “Specification for DNS over Transport Layer Security (TLS)”

The Internet RFC-7858, “Specification for DNS over Transport Layer Security (TLS)”, was just released by the ITEF as a Standards Track document.

From the abstract:

This document describes the use of Transport Layer Security (TLS) to provide privacy for DNS. Encryption provided by TLS eliminates opportunities for eavesdropping and on-path tampering with DNS queries in the network, such as discussed in RFC 7626. In addition, this document specifies two usage profiles for DNS over TLS and provides advice on performance considerations to minimize overhead from using TCP and TLS with DNS.

This document focuses on securing stub-to-recursive traffic, as per
the charter of the DPRIVE Working Group. It does not prevent future applications of the protocol to recursive-to-authoritative traffic.

This RFC is joint work of Zhi Hu, Liang Zhu, John Heidemann, Allison Mankin, Duane Wessels, and Paul Hoffman, of USC/ISI, Verisign, ICANN, and independent (at different times).  This RFC is one result of our prior paper “Connection-Oriented DNS to Improve Privacy and Security”, but also represents the input of the DPRIVE IETF working group (Warren Kumari and Tim Wicinski, chairs), where it is one of a set of RFCs designed to improve DNS privacy.

On to deployments!

Categories
Papers Publications

new conference paper “Measuring the Latency and Pervasiveness of TLS Certificate Revocation” in PAM 2016

The paper “Measuring the Latency and Pervasiveness of TLS Certificate Revocation” will appear at Passive and Active Measurements Conference in March 2016 in Heraklion, Crete, Greece  (available at http://www.isi.edu/~liangzhu/papers/Zhu16a.pdf)

From the abstract:

Today, Transport-Layer Security (TLS) is the bedrock of Internet security for the web and web-derived applications. TLS depends on the X.509 Public Key Infrastructure (PKI) to authenticate endpoint
identity. An essential part of a PKI is the ability to quickly revoke certificates, for example, after a key compromise. Today the Online Certificate Status Protocol (OCSP) is the most common way to quickly distribute revocation information. However, prior and current concerns about OCSP latency and privacy raise questions about its use. We examine OCSP using passive network monitoring of live traffic at the Internet uplink of a large research university and verify the results using active scans. Our measurements show that the median latency of OCSP queries is quite good: only 20 ms today, much less than the 291 ms observed in 2012. This improvement is because content delivery networks (CDNs) serve most OCSP traffic today; our measurements show 94% of queries are served by CDNs. We also show that OCSP use is ubiquitous today: it is used by all popular web browsers, as well as important non-web applications such as MS-Windows code signing.

The work in the paper is by Liang Zhu (USC/ISI), Johanna Amann (ICSI) and John Heidemann (USC/ISI). The active probe dataset in this paper is available upon request.

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 “Measuring DANE TLSA Deployment” in TMA 2015

The paper “Measuring DANE TLSA Deployment” will appear at the Traffic Monitoring and Analysis Workshop in April 2015 in Barcelona, Spain (available at http://www.isi.edu/~liangzhu/papers/dane_tlsa.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 serves to complement traditional certificate authentication methods, which 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 paper 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 485k signed zones, we find only 997 TLSA names. We characterize how it is being used so far, and find that around 7–13% of TLSA records are invalid. We find 33% of TLSA responses are larger than 1500 Bytes and will very likely be fragmented.

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

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 “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.