Practical realisation and elimination of an ECC-related software bug attack

We analyse and exploit implementation features in OpenSSL version 0.9.8g which permit an attack against ECDH-based functionality. The attack, although more general, can recover the entire (static) private key from an associated SSL server via $633$ adaptive queries when the NIST curve P-256 is used. One can view it as a software-oriented analogue of the bug attack concept due to Biham et al. and, consequently, as the first bug attack to be successfully applied against a real-world system. In addition to the attack and a posteriori countermeasures, we show that formal verification, while rarely used at present, is a viable means of detecting the features which the attack hinges on. Based on the security implications of the attack and the extra justification posed by the possibility of intentionally incorrect implementations in collaborative software development, we conclude that applying and extending the coverage of formal verification to augment existing test strategies for OpenSSL-like software should be deemed a worthwhile, long-term challenge.This work has been supported in part by EPSRC via grant EP/H001689/1 and by project SMART, funded by ENIAC Joint Undertaking (GA 120224)

In search of CurveSwap: Measuring elliptic curve implementations in the wild

We survey elliptic curve implementations from several vantage points. We perform internet-wide scans for TLS on a large number of ports, as well as SSH and IPsec to measure elliptic curve support and implementation behaviors, and collect passive measurements of client curve support for TLS. We also perform active measurements to estimate server vulnerability to known attacks against elliptic curve implementations, including support for weak curves, invalid curve attacks, and curve twist attacks. We estimate that 0.77% of HTTPS hosts, 0.04% of SSH hosts, and 4.04% of IKEv2 hosts that support elliptic curves do not perform curve validity checks as specified in elliptic curve standards. We describe how such vulnerabilities could be used to construct an elliptic curve parameter downgrade attack called CurveSwap for TLS, and observe that there do not appear to be combinations of weak behaviors we examined enabling a feasible CurveSwap attack in the wild. We also analyze source code for elliptic curve implementations, and find that a number of libraries fail to perform point validation for JSON Web Encryption, and find a flaw in the Java and NSS multiplication algorithms

Degenerate Fault Attacks on Elliptic Curve Parameters in OpenSSL

In this paper, we describe several practically exploitable fault attacks against OpenSSL\u27s implementation of elliptic curve cryptography, related to the singular curve point decompression attacks of Blömer and Günther (FDTC2015) and the degenerate curve attacks of Neves and Tibouchi (PKC 2016). In particular, we show that OpenSSL allows to construct EC key files containing explicit curve parameters with a compressed base point. A simple single fault injection upon loading such a file yields a full key recovery attack when the key file is used for signing with ECDSA, and a complete recovery of the plaintext when the file is used for encryption using an algorithm like ECIES. The attack is especially devastating against curves with $j$-invariant equal to 0 such as the Bitcoin curve secp256k1, for which key recovery reduces to a single division in the base field. Additionally, we apply the present fault attack technique to OpenSSL\u27s implementation of ECDH, by combining it with Neves and Tibouchi\u27s degenerate curve attack. This version of the attack applies to usual named curve parameters with nonzero $j$-invariant, such as P192 and P256. Although it is typically more computationally expensive than the one against signatures and encryption, and requires multiple faulty outputs from the server, it can recover the entire static secret key of the server even in the presence of point validation. These various attacks can be mounted with only a single instruction skipping fault, and therefore can be easily injected using low-cost voltage glitches on embedded devices. We validated them in practice using concrete fault injection experiments on a Rapsberry Pi single board computer running the up to date OpenSSL command line tools---a setting where the threat of fault attacks is quite significant

Elliptic Curve Cryptography in Practice

In this paper, we perform a review of elliptic curve cryptography (ECC), as it is used in practice today, in order to reveal unique mistakes and vulnerabilities that arise in implementations of ECC. We study four popular protocols that make use of this type of public-key cryptography: Bitcoin, secure shell (SSH), transport layer security (TLS), and the Austrian e-ID card. We are pleased to observe that about 1 in 10 systems support ECC across the TLS and SSH protocols. However, we find that despite the high stakes of money, access and resources protected by ECC, implementations suffer from vulnerabilities similar to those that plague previous cryptographic systems

Measuring And Securing Cryptographic Deployments

This dissertation examines security vulnerabilities that arise due to communication failures and incentive mismatches along the path from cryptographic algorithm design to eventual deployment. I present six case studies demonstrating vulnerabilities in real-world cryptographic deployments. I also provide a framework with which to analyze the root cause of cryptographic vulnerabilities by characterizing them as failures in four key stages of the deployment process: algorithm design and cryptanalysis, standardization, implementation, and endpoint deployment. Each stage of this process is error-prone and influenced by various external factors, the incentives of which are not always aligned with security. I validate the framework by applying it to the six presented case studies, tracing each vulnerability back to communication failures or incentive mismatches in the deployment process. To curate these case studies, I develop novel techniques to measure both existing and new cryptographic attacks, and demonstrate the widespread impact of these attacks on real-world systems through measurement and cryptanalysis. While I do not claim that all cryptographic vulnerabilities can be described with this framework, I present a non-trivial (in fact substantial) number of case studies demonstrating that this framework characterizes the root cause of failures in a diverse set of cryptographic deployments

Fooling primality tests on smartcards

We analyse whether the smartcards of the JavaCard platform correctly validate primality of domain parameters. The work is inspired by the paper Prime and prejudice: primality testing under adversarial conditions, where the authors analysed many open-source libraries and constructed pseudoprimes fooling the primality testing functions. However, in the case of smartcards, often there is no way to invoke the primality test directly, so we trigger it by replacing (EC)DSA and (EC)DH prime domain parameters by adversarial composites. Such a replacement results in vulnerability to Pohlig-Hellman style attacks, leading to private key recovery. Out of nine smartcards (produced by five major manufacturers) we tested, all but one have no primality test in parameter validation. As the JavaCard platform provides no public primality testing API, the problem cannot be fixed by an extra parameter check, %an additional check before the parameters are passed to existing (EC)DSA and (EC)DH functions, making it difficult to mitigate in already deployed smartcards

Security technologies for wireless access to local area networks

In today’s world, computers and networks are connected to all life aspects and professions. The amount of information, personal and organizational, spread over the network is increasing exponentially. Simultaneously, malicious attacks are being developed at the same speed, which makes having a secure network system a crucial factor on every level and in any organization. Achieving a high protection level has been the goal of many organizations, such as the Wi-Fi Alliance R , and many standards and protocols have been developed over time. This work addresses the historical development of WLAN security technologies, starting from the oldest standard, WEP, and reaching the newly released standard WPA3, passing through the several versions in between,WPA, WPS, WPA2, and EAP. Along with WPA3, this work addresses two newer certificates, Enhanced OpenTM and Easy ConnectTM. Furthermore, a comparative analysis of the previous standards is also presented, detailing their security mechanisms, flaws, attacks, and the measures they have adopted to prevent these attacks. Focusing on the new released WPA3, this work presents a deep study on both WPA3 and EAP-pwd. The development of WPA3 had the objective of providing strong protection, even if the network’s password is considered weak. However, this objective was not fully accomplished and some recent research work discovered design flaws in this new standard. Along with the above studies, this master thesis’ work builds also a network for penetration testing using a set of new devices that support the new standard. A group of possible attacks onWi-Fi latest security standards was implemented on the network, testing the response against each of them, discussing the reason behind the success or the failure of the attack, and providing a set of countermeasures applicable against these attacks. Obtained results show that WPA3 has overcome many of WPA2’s issues, however, it is still unable to overcome some major Wi-Fi vulnerabilities.No mundo de hoje, os computadores e as redes estão conectados praticamente a todos os aspectos da nossa vida pessoal e profissional. A quantidade de informações, pessoais e organizacionais, espalhadas pela rede está a aumentar exponencialmente. Simultaneamente, também os ataques maliciosos estão a aumentar à mesma velocidade, o que faz com que um sistema de rede seguro seja um fator crucial a todos os níveis e em qualquer organização. Alcançar altos níveis de proteção tem sido o objetivo de trabalho de muitas organizações, como a Wi-Fi Alliance R , tendo muitos standards e protocolos sido desenvolvidos ao longo do tempo. Este trabalho aborda o desenvolvimento histórico das tecnologias de segurança para WLANs, começando pelo standard mais antigo, WEP, e acabando no recém-chegado WPA3, passando pelas várias versões intermedias, WPA, WPS, WPA2 e EAP. Juntamente com o WPA3, este trabalho aborda os dois certificados mais recentes, Enhanced OpenTM e Easy ConnectTM. Além disso, também é apresentada uma análise comparativa dos standards anteriores, detalhando os seus principais mecanismos de segurança, falhas, ataques a que são susceptíveis e medidas adotadas para evitar esses ataques. Quanto ao novo WPA3 e EAP-pwd, este trabalho apresenta um estudo aprofundado sobre os seus modos "Personal" e "Enterprise". O desenvolvimento do WPA3 teve por objetivo fornecer proteção forte, mesmo que a password de rede seja considerada fraca. No entanto, esse objetivo não foi totalmente alcançado e alguma investigação realizada recentemente detectou falhas de desenho nesse novo padrão. Juntamente com os estudo dos standards acima referidos, o trabalho realizado para esta tese de mestrado também constrói uma rede para testes de penetração usando um conjunto de novos dispositivos que já suportam o novo standard. São aplicados vários ataques aos mais recentes padrões de segurança Wi-Fi, é testada a sua resposta contra cada um deles, é discutindo o motivo que justifica o sucesso ou a falha do ataque, e são indicadas contramedidas aplicáveis a esses ataques. Os resultados obtidos mostram que o WPA3 superou muitos dos problemas do WPA2 mas que, no entanto, ainda é incapaz de superar algumas das vulnerabilidades presentes nas redes Wi-Fi.First, I would like to express my deepest appreciation to those who gave me the possibility to complete my study and get my Master degree, the Aga Khan Foundation, who has supported me financiall