Category Archives: Protocols

Three Paper Thursday: Vulnerabilities! We’ve got vulnerabilities here! … See? Nobody cares.

Jurassic Park is often (mistakenly) left out of the hacker movie canon. It clearly demonstrated the risk of an insider attack on control systems (Velociraptor rampage, amongst other tragedies…) nearly a decade ahead of the Maroochy sewage incident, it’s the first film I know of with a digital troll (“ah, ah, ah, you didn’t say the magic word!”), and Samuel L. Jackson correctly assesses the possible consequence of a hard reset (namely, everyone dying), resulting in his legendary “Hold on to your butts”. The quotable mayhem is seeded early in the film, when biotech spy Lewis Dodgson gives a sack of money to InGen’s Dennis Nedry to steal some dino DNA. Dodgson’s caricatured OPSEC (complete with trilby and dark glasses) is mocked by Nedry shouting, “Dodgson! Dodgson! We’ve got Dodgson here! See, nobody cares…” Three decades later, this quote still comes to mind* whenever conventional wisdom doesn’t seem to square with observed reality, and today we’re going to apply it to the oft-maligned world of Industrial Control System (ICS) security.

There is plenty of literature on ICS security pre-2010, but people really sat up and started paying attention when we learned about Stuxnet. Possibly the most upsetting thing about Stuxnet (for security-complacent control system designers like me) was the apparent ease with which the “air gap” was bridged over and over again. Any remaining faith in the air gap was killed by Éireann Leverett’s demonstration (thesis and S4 presentation) that thousands of industrial systems were directly connected to the Internet — no air gap jumping required. Since then, we’ve observed a steady growth in Internet-connected ICS devices, due both to improved search techniques and increasingly-connectable ICS devices. On any given day you can find about 100,000 unique devices speaking industrial protocols on Censys and Shodan. These protocols are largely unauthenticated and unencrypted, allowing an attacker that can speak the protocol to remotely read state, issue commands, and even modify programmable logic without using an actual exploit.

This sounds (and is) bad, and people have (correctly) highlighted its badness on many occasions. The attacks, however, appear to be missing: we are not aware of a single instance of industrial damage initiated via an Internet-connected ICS device. In this Three Paper Thursday we’ll look at papers showing how easy it is to find and contextualise Internet-connected ICS devices, some evidence for lack of malicious interest, and some leading indicators that this happy conclusion (for which we don’t really deserve any credit) may be changing.

*Perhaps because guys of a certain age still laugh and say “Dodson! We’ve got Dodson here!” when they learn my surname. I try to explain that it’s spelt differently, but…
Continue reading Three Paper Thursday: Vulnerabilities! We’ve got vulnerabilities here! … See? Nobody cares.

Honware: A Virtual Honeypot Framework for Capturing CPE and IoT Zero Days

Existing defenses are slow to detect zero day exploits and capture attack traffic targeting inadequately secured Customer Premise Equipment (CPE) and Internet of Things (IoT) devices. This means that attackers have considerable periods of time to find and compromise vulnerable devices before the attack vectors are well understood and mitigation is in place.

About a month ago we presented honware at eCrime 2019, a new honeypot framework that enables the rapid construction of honeypots for a wide range of CPE and IoT devices. The framework automatically processes a standard firmware image (as is commonly provided for updates) and runs the system with a special pre-built Linux kernel without needing custom hardware. It then logs attacker traffic and records which of their actions led to a compromise.

We provide an extensive evaluation and show that our framework is scalable and significantly better than existing emulation strategies in emulating the devices’ firmware applications. We were able to successfully process close to 2000 firmware images across a dozen brands (TP-Link, Netgear, D-Link…) and run them as honeypots. Also, as we use the original firmware images, the honeypots are not susceptible to fingerprinting attacks based on protocol deviations or self-revealing properties.

By simplifying the process of deploying realistic honeypots at Internet scale, honware supports the detection of malware types that often go unnoticed by users and manufactures. We hope that honware will be used at Internet scale by manufacturers setting up honeypots for all of their products and firmware versions or by researchers looking for new types of malware.

The paper is available here.

Open Source Summit Europe

I am at the 2018 Open Source Summit Europe in Edinburgh where I’ll be speaking about Hyperledger projects. In follow-ups to this post, I’ll live-blog security related talks and workshops.

The first workshop of the summit I attended was a crash course introduction to EdgeX Foundry by Jim White, the organization’s chief architect. EdgeX Foundry is an open source, vendor neutral software framework for IoT edge computing. One of the primary challenges that it faces is the sheer number of protocols and standards that need to be supported in the IoT space, both on the south side (various sensors and actuators) as well as the north side (cloud providers, on-premise servers). To do this, EdgeX uses a microservices based architecture where all components interact via configurable APIs and developers can choose to customize any component. While this architecture does help to alleviate the scaling issue, it raises interesting questions with respect to API security and device management. How do we ensure the integrity of the control and command modules when those modules themselves are federated across multiple third-party-contributed microservices? The team at EdgeX is aware of these issues and is a major theme of focus for their upcoming releases.

How Protocols Evolve

Over the last thirty years or so, we’ve seen security protocols evolving in different ways, at different speeds, and at different levels in the stack. Today’s TLS is much more complex than the early SSL of the mid-1990s; the EMV card-payment protocols we now use at ATMs are much more complex than the ISO 8583 protocols used in the eighties when ATM networking was being developed; and there are similar stories for GSM/3g/4g, SSH and much else.

How do we make sense of all this?

Reconciling Multiple Objectives – Politics or Markets? was particularly inspired by Jan Groenewegen’s model of innovation according to which the rate of change depends on the granularity of change. Can a new protocol be adopted by individuals, or does it need companies to adopt it en masse for internal use, or does it need to spread through a whole ecosystem, or – the hardest case of all – does it require a change in culture, norms or values?

Security engineers tend to neglect such “soft” aspects of engineering, and we probably shouldn’t. So we sketch a model of the innovation stack for security and draw a few lessons.

Perhaps the most overlooked need in security engineering, particularly in the early stages of a system’s evolution, is recourse. Just as early ATM and point-of-sale system operators often turned away fraud victims claiming “Our systems are secure so it must have been your fault”, so nowadays people who suffer abuse on social media can find that there’s nowhere to turn. A prudent engineer should anticipate disputes, and give some thought in advance to how they should be resolved.

Reconciling Multiple Objectives appeared at Security Protocols 2017. I forgot to put the accepted version online and in the repository after the proceedings were published in late 2017. Sorry about that. Fortunately the REF rule that papers must be made open access within three months doesn’t apply to conference proceedings that are a book series; it may be of value to others to know this!

Bitter Harvest: Systematically Fingerprinting Low- and Medium-interaction Honeypots at Internet Scale

Next week we will present a new paper at USENIX WOOT 2018, in which we show that we can find low- and medium-interaction honeypots on the Internet with a few packets. So if you are running such a honeypot (Cowrie, Glastopf, Conpot etc.), then “we know where you live” and the bad guys might soon as well.

In total, we identify 7,605 honeypot instances across nine different honeypot implementations for the most important network protocols SSH, Telnet, and HTTP.

These honeypots rely on standard libraries to implement large parts of the transport layer, but they were never intended to provide identical behaviour to the systems being impersonated. We show that fixing the identity string pretending to be OpenSSH or Apache and not “any” library or fixing other common identifiers such as error messages is not enough. The problem is that there are literally thousands of distinguishing protocol interactions, part of the contribution of the paper is to show how to pick the “best” one. Even worse, to fingerprint these honeypots, we do not need to send any credentials so it will be hard to tell from the logging that you have been detected.

We also find that many honeypots are deployed and forgotten about because part of the fingerprinting has been to determine how many people are not actively patching their systems! We find that  27% of the SSH honeypots have not been updated within the last 31 months and only 39% incorporate improvements from 7 months ago. It turns out that security professionals are as bad as anyone.

We argue that our method is a  ‘class break’ in that trivial patches cannot address the issue. Thus we need to move on from the current dominant honeypot architecture of python libraries and python programs for low- and medium-interaction honeypots. We also have developed a modified version of the OpenSSH daemon (sshd) which can front-end a Cowrie instance so that the protocol layer distinguishers will no longer work.

The paper is available here.

The two-time pad: midwife of information theory?

The NSA has declassified a fascinating account by John Tiltman, one of Britain’s top cryptanalysts during world war 2, of the work he did against Russian ciphers in the 1920s and 30s.

In it, he reveals (first para, page 8) that from the the time the Russians first introduced one-time pads in 1928, they actually allowed these pads to be used twice.

This was still a vast improvement on the weak ciphers and code books the Russians had used previously. Tiltman notes ruefully that “We were hardly able to read anything at all except in the case of one or two very stereotyped proforma messages”.

Now after Gilbert Vernam developed encryption using xor with a key tape, Joseph Mauborgne suggested using it one time only for security, and this may have seemed natural in the context of a cable company. When the Russians developed their manual system (which may have been inspired by the U.S. work or a German one-time pad developed earlier in the 1920s) they presumably reckoned that using them twice was safe enough.

They were spectacularly wrong. The USA started Operation Venona in 1943 to decrypt messages where one-time pads had been reused, and this later became one of the first applications of computers to cryptanalysis, leading to the exposure of spies such as Blunt and Cairncross. The late Bob Morris, chief scientist at the NSA, used to warn us enigmatically of “The Two-time pad”. The story up till now was that the Russians must have reused pads under pressure of war, when it became difficult to get couriers through to embassies. Now it seems to have been Russian policy all along.

Many people have wondered what classified war work might have inspired Claude Shannon to write his stunning papers at the end of WW2 in which he established the mathematical basis of cryptography, and of information more generally.

Good research usually comes from real problems. And here was a real problem, which demanded careful clarification of two questions. Exactly why was the one-time pad good and the two-time pad bad? And how can you measure the actual amount of information in an English (or Russian) plaintext telegram: is it more or less than half the amount of information you might squeeze into that many bits? These questions are very much sharper for the two-time pad than for rotor machines or the older field ciphers.

That at least was what suddenly struck me on reading Tiltman. Of course this is supposition; but perhaps there are interesting documents about Shannon’s war work to be flushed out with freedom of information requests. (Hat tip: thanks to Dave Banisar for pointing us at the Tiltman paper.)