Category Archives: Three Paper Thursday

Three Paper Thursday: Exploring the Impact of Online Crime Victimization

Just as in other types of victimization, victims of cybercrime can experience serious consequences, emotional or not. First of all, a repeat victim of a cyber-attack might face serious financial or emotional hardship. These victims are also more likely to require medical attention as a consequence of online fraud victimization. This means repeat victims have a unique set of support needs, including the need for counselling, and seeking support from the criminal justice system. There are also cases, such as in cyberbullying or sextortion, where victims will not speak to their family and friends. These victims feel too ashamed to share details with others and they will probably not receive any support. In such cases trauma can even lead to self-harm. Therefore, we see that online victimization can actually lead to physical harm. 

As a member of the National Risk Assessment (NRA) Behavioural Science Expert Group in the UK, working on the social and psychological impact of cyber-attacks on members of the public, I have identified for years now that the actual social or psychological impact of different types of cyber-attacks to victims or society as a whole is still not explored. Governments have been slow in identifying and analysing potential events online that may negatively impact individuals. In the UK, as well as in other countries, cybercrime has been added as part of a national risk assessment exercise only a few years ago. Therefore, our knowledge about the potential impact of cyber-attacks and their cascading effects are still being under research.  

This is often a very difficult area for lawyers and the courts to understand. Understanding victims’ needs and the responsibilities of the police, the judiciary and other authorities in dealing with such crimes is very important. This is why we need to further explore how and to what extent the situation and needs of victims of online crimes differ from those of traditional offline crimes. By sharing experiences and openly discussing about this issue, we will be able to engrain the cybersecurity mindset in our societies thus preventing victimization in some level. 

In this post I would like to introduce recent work in this area. The first one explores the social and psychological impact of cyber-attacks to individuals as well as nations, the second one explores the differences between the situation and needs of online and offline crime victims while the third one discusses the relationship between offending and victimization online.

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Three Paper Thursday: Attacking the Bitcoin Peer-to-Peer Network

People have tried to develop many different attack vectors on cryptocurrencies, from codebase flaws, cryptographic algorithms, mining processes, consensus protocols and block propagation mechanisms to the underlying network layer. Most attacks could be patched quickly by modifying the source code, but preventing attacks that exploit the network layer remains a non-trivial problem as the network layer heavily relies on the existing Internet infrastructure, which is impractical to change. So network-layer attacks could be dangerous, powerful and hard to mitigate.

In this post, I would like to introduce some recent attacks against the Bitcoin P2P network. Continue reading Three Paper Thursday: Attacking the Bitcoin Peer-to-Peer Network

Three Paper Thursday: Adversarial Machine Learning, Humans and everything in between

Recent advancements in Machine Learning (ML) have taught us two main lessons: a large proportion of things that humans do can actually be automated, and that a substantial part of this automation can be done with minimal human supervision. One no longer needs to select features for models to use; in many cases people are moving away from selecting the models themselves and perform a Network Architecture Search. This means non-stop search across billions of dimensions, ever improving different properties of deep neural networks (DNNs).

However, progress in automation has brought a spectre to the feast. Automated systems seem to be very vulnerable to adversarial attacks. Not only is this vulnerability hard to get rid of; worse, we often can’t even define what it means to be vulnerable in the first place.

Furthermore, finding adversarial attacks on ML systems is really easy even if you do not have any access to the models. There are only so many things that make cat a cat, and all the different models that deal with cats will be looking at the same set of features. This has an important implication: learning how to trick one model dealing with cats often transfers over to other models. Transferability is a terrible property for security because it makes adversarial ML attacks cheap and scalable. If there is a camera in the bank running a similar ML model to the camera you can get in Costco for $5, then the cost of developing an attack is $5.

As of now, we do not really have good answers to any of these questions. In the meantime, ML controlled systems are entering the human realm.

In this Three Paper Thursday I want to talk about works from the field of adversarial ML that make it much more understandable.

Continue reading Three Paper Thursday: Adversarial Machine Learning, Humans and everything in between

Three Paper Thursday: The role of intermediaries, platforms, and infrastructures in governing crime and abuse

The platforms, providers, and infrastructures which together make up the contemporary Internet play an increasingly central role in the business of governing human societies. Although the software engineers, administrators, business professionals, and other staff working at these organisations may not have the institutional powers of state organisations such as law enforcement or the civil service, they are now in a powerful position of responsibility for the harms and illegal activities which their platforms facilitate. For this Three Paper Thursday, I’ve chosen to highlight papers which address these issues, and which explore the complex networks of different infrastructural actors and perspectives which play a role in the reporting, handling, and defining of abuse and crime online.

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Three Paper Thursday: Sanitisers and Mitigators

In this reboot of the Three Paper Thursdays, back after a hiatus of almost eight years, I consider the many different ways in which programs can be sanitised to detect, or mitigated to prevent the use of, the many programmer errors that can introduce security vulerabilities in low-level languages such as C and C++. We first look at a new binary translation technique, before covering the many compiler techniques in the literature, and finally finishing off with my own hardware analysis architecture.

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Three Paper Thursday: ISSISP2012

I’ve just returned from the 2012 International Summer School on Information Security and Protection (ISSISP2012) held at the University of Arizona. This annual summer school brings together a mix of academic researchers and industry practitioners in the field of software protection where the main philosophy, and indeed the only viable approach available, can be summed up as “Security through Obscurity”. The goal here is to impede reverse engineering and to hide algorithms and data in the presence of disassemblers, decompilers, debuggers as well as side-channel analysis – this is the Man-at-the-End (MATE) attack. White box cryptography, I’ve learnt, is the term used to describe the protection of cryptographic primitives and keys against this kind of attack. This week I wish to highlight 3 talks/papers which I found memorable – the first 2 describe techniques to address code injection and timing side-channel attacks; the last one discusses formally verified program obfuscators.

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Three paper Thursday: Shamir x3 at Eurocrypt

For the past 4 days Cambridge has been hosting Eurocrypt 2012.

There were many talks, probably interesting, but I will only comment on 3 talks given by Adi Shamir, 1 during the official conference and 2 during the rump session.
Among the other sessions I mention that the best paper was given to this paper by Antoine Joux and Vanessa Vitse for the enhancement of index calculus to break elliptic curves.

Official Talk: Minimalism in cryptography, the Even-Mansour scheme revisited

In this work, Adi et al. presented an analysis on the Even-Mansour scheme:

E(P) = F(P ⊕ K1) ⊕ K2

Such scheme, some times referred to as key whitening, is used in the DESX construction and in the AES-XTS mode of operation (just a few examples).

Adi et al. shown a new slide attack, called SLIDEX, which has been used to prove a tight bound on the security of the Even-Mansour scheme.

Even more, they show that using K1 = K2 you can achieve the same security.

Rump talk 1: security of multiple key encryption

Here Adi considered the case of encrypting data multiple times with multiple keys, as in 3DES:
data -> c1 = E_k1(data) ->  c2 = E_k2(c1) -> c3 = E_k3(c2) -> c4 = E_k3(c3) …. and so on.

The general approach to break a scheme where a key is used 2 times or 3 times (2DES, 3DES for e.g.) is the meet-in-the-middle attack, where you encrypt from one side and then decrypt from the other side, and by storing a table of the size of the key space (say n bits) you can eventually find the keys used in a scheme using only a few pairs of plaintext/ciphertext. For 2 keys such an attack would require 2^{n} time, for 3 keys 2^{2n}. Therefore some people may assume that increasing the number of keys by 1 (i.e. to use 4 keys) may increase the security of this scheme. This is in fact not true.

Adi shown that once we go beyond 3 keys (e.g. 4, 5, 6, etc…) the security only increases once every few keys. If you think of it, using 4 keys you can just apply the meet-in-the-middle attack in 2^{2n} time to the left 2 encryptions and also in 2^{2n} time to the right 2 decryptions. After this, he shown how to use the meet-in-the-middle attack to solve the knapsack problem and proposed the idea of using such an algorithm to solve other problems as well.

Rump talk 2: the cryptography of John Nash

Apparently John Nash, member of MIT during the 1950s, wrote some letters to the NSA in 1955 explaining the implications of computational complexity for security (this wasn’t known at the time).

John Nach also sent a proposal for an encryption scheme that is similar with today’s stream ciphers. However the NSA’s replied saying that the scheme didn’t match the security requirements of the US.
Adi Shamir and Ron Rivest then analysed the scheme and found that in the known plaintext model it would require something like 2^{sqrt(n)} time to break (which John Nach considered not to be a polynomial time, and therefore assumed would be secure).

The letters are now declassified. This blog also comments on the story.

Three Paper Thursday: full disk encryption

Information is often an important asset and today’s information is commonly stored as digital data (bytes). We store this data in our computers local hard disks and in our laptops disks. Many organisations wish to keep the data stored in their computers and laptops confidential. Therefore a natural desire is that a stolen disk or laptop should not be readable by an external person (an attacker in general terms). For this reason we use encryption.

A hard disk is commonly logically organised in multiple sections, often referred to as either partitions or volumes. These volumes can be used for various purposes, and they are often structured according to a file system format (e.g. NTFS, FAT, HFS, etc.). It is possible to have a single disk with 3 volumes, where the first volume is formatted with NTFS and contains a Windows operating system, the second volume is formatted with EXT3 file system and contains an installation of a Linux distribution, while the third volume is formatted with FAT file system and only contains data (no operating system).

Volume encryption is a mechanism used to encrypt the contents of an entire volume. This is sometimes referred as “full disk encryption”, which is misleading, since a physical disk can actually contain multiple volumes, each encrypted independently.  However, since the term has become very popular, I will continue to refer to this kind of encryption as “full disk encryption” but the reader should keep the above distinction in mind.

There are several products that offer full disk encryption, e.g. PGP Whole Disk Encryption, TrueCrypt, Sophos SafeGuard, or Check Point FDE. Bitlocker is the full disk encryption integrated with the Windows OS and Apple has recently introduced FileVault 2 as full disk encryption from MAC OS X 10.7.

There are several limitations that affect the encryption of an entire disk. These have to do with 3 important aspects among others: a) encryption must be fast (a user should not notice any extra latency); b) the operating system is encrypted as well (so there must be some way of bootstrapping the decryption process when the computer boots)  c) the encryption mechanism should not reduce the available storage space noticeable (that is, we cannot use an extra block of data for every few encrypted blocks).

The following 3 papers explain in detail these limitations. Two of them relate to currently deployed full disk encryption systems.

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Three Paper Thursday: BGP and its security

BGP security was a hot topic a few years ago, but is not as much studied these years. However, with technologies such as IPv6 and DNSSEC, BGP security is making a comeback, especially in the industry. We academics also have much to contribute in this space. In today’s Three Paper Thursday, I will highlight three recent work related to BGP security. It is also a good starting point to catch up in BGP security for those whose last memories of BGP security involve proposals such as S-BGP and SoBGP.

Three Paper Thursday: Binary analysis and Security

Mention the phrase “binary reverse engineering” or “binary analysis” and it often conjures up an image of software pirates or hacking groups. However, there are practical reasons for doing analysis on machine code. For instance, machines don’t run source code, they run machine code – how do we know it’s running correctly? Malware doesn’t usually come with source code (but they are known to leak on occasion); How do we protect our software from discovered vulnerabilities if we’re unable to re-compile the program from the original source code? For three paper Thursday this week, my contribution is to highlight three representative security applications of binary analysis, namely software testing, malware analysis and software protection. Continue reading Three Paper Thursday: Binary analysis and Security