PapersCut A shortcut to recent security papers

Adversarially robust transfer learning

Authors: Ali Shafahi, Parsa Saadatpanah, Chen Zhu, Amin Ghiasi, Christoph Studer, David Jacobs, Tom Goldstein

Abstract: Transfer learning, in which a network is trained on one task and re-purposed on another, is often used to produce neural network classifiers when data is scarce or full-scale training is too costly. When the goal is to produce a model that is not only accurate but also adversarially robust, data scarcity and computational limitations become even more cumbersome. We consider robust transfer learning, in which we transfer not only performance but also robustness from a source model to a target domain. We start by observing that robust networks contain robust feature extractors. By training classifiers on top of these feature extractors, we produce new models that inherit the robustness of their parent networks. We then consider the case of fine-tuning a network by re-training end-to-end in the target domain. When using lifelong learning strategies, this process preserves the robustness of the source network while achieving high accuracy. By using such strategies, it is possible to produce accurate and robust models with little data, and without the cost of adversarial training.

Date: 20 May 2019

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Increasing the Security of Weak Passwords: the SPARTAN Interface

Authors: Sarah C. Helble, Alexander J. Gartner, Jennifer A. McKneely

Abstract: Password authentication suffers from the well-known tradeoff between security and usability. Secure passwords are difficult for users to remember, and memorable passwords are often easy to guess. SPARse Two-dimensional AuthenticatioN (SPARTAN) allows users to input their textual passwords in a two-dimensional grid instead of a linear textbox. This interface enables relatively short passwords to have a higher calculated level of security due to the need for an attacker to determine both the text of the password and the location of each character in the grid. We created a SPARTAN prototype and conducted a preliminary user study to evaluate the actual usability and security of the SPARTAN interface compared to the linear password entry interface. We find that while user-created SPARTAN passwords tend to be shorter than their linear counterparts, the calculated security of user-created SPARTAN passwords is higher than that of user-created linear passwords. We also asked participants to complete a survey on the usability of the SPARTAN interface and identified some areas of improvement, while prototype interaction provided evidence of users becoming more familiar with SPARTAN over time. Finally, we performed an investigation into password-cracking tools, and assert that SPARTAN passwords require more resources to crack than their linear counterparts. These findings suggest that SPARTAN is a promising alternative to linear passwords from a security standpoint. Usability of the interface and memorability of SPARTAN passwords is an interesting research question and should be further investigated in future work.

Date: 20 May 2019

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Secure Extensibility for System State Extraction via Plugin Sandboxing

Authors: Sahil Suneja, Canturk Isci

Abstract: We introduce a new mechanism to securely extend systems data collection software with potentially untrusted third-party code. Unlike existing tools which run extension modules or plugins directly inside the monitored endpoint (the guest), we run plugins inside a specially crafted sandbox, so as to protect the guest as well as the software core. To get the right mix of accessibility and constraints required for systems data extraction, we create our sandbox by combining multiple features exported by an unmodified kernel. We have tested its applicability by successfully sandboxing plugins of an opensourced data collection software for containerized guest systems. We have also verified its security posture in terms of successful containment of several exploits, which would have otherwise directly impacted a guest, if shipped inside third-party plugins.

Date: 20 May 2019

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simTPM: User-centric TPM for Mobile Devices (Technical Report)

Authors: Dhiman Chakraborty, Lucjan Hanzlik, Sven Bugiel

Abstract: Trusted Platform Modules are valuable building blocks for security solutions and have also been recognized as beneficial for security on mobile platforms, like smartphones and tablets. However, strict space, cost, and power constraints of mobile devices prohibit an implementation as dedicated on-board chip and the incumbent implementations are software TPMs protected by Trusted Execution Environments. In this paper, we present simTPM, an alternative implementation of a mobile TPM based on the SIM card available in mobile platforms. We solve the technical challenge of implementing a TPM2.0 in the resource-constrained SIM card environment and integrate our simTPM into the secure boot chain of the ARM Trusted Firmware on a HiKey960 reference board. Most notably, we address the challenge of how a removable TPM can be bound to the host device's root of trust for measurement. As such, our solution not only provides a mobile TPM that avoids additional hardware while using a dedicated, strongly protected environment, but also offers promising synergies with co-existing TEE-based TPMs. In particular, simTPM offers a user-centric trusted module. Using performance benchmarks, we show that our simTPM has competitive speed with a reported TEE-based TPM and a hardware-based TPM.

Comment: Accepted at 28th Usenix Security Symposium, 2019. This is the longer version. The bibtex is required as soon as possible, for the camera ready version for the conference

Date: 20 May 2019

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Safety vs. Security: Attacking Avionic Systems with Humans in the Loop

Authors: Matthew Smith, Martin Strohmeier, Jon Harman, Vincent Lenders, Ivan Martinovic

Abstract: Many wireless communications systems found in aircraft lack standard security mechanisms, leaving them fundamentally vulnerable to attack. With affordable software-defined radios available, a novel threat has emerged, allowing a wide range of attackers to easily interfere with wireless avionic systems. Whilst these vulnerabilities are known, concrete attacks that exploit them are still novel and not yet well understood. This is true in particular with regards to their kinetic impact on the handling of the attacked aircraft and consequently its safety. To investigate this, we invited 30 Airbus A320 type-rated pilots to fly simulator scenarios in which they were subjected to attacks on their avionics. We implement and analyse novel wireless attacks on three safety-related systems: Traffic Collision Avoidance System (TCAS), Ground Proximity Warning System (GPWS) and the Instrument Landing System (ILS). We found that all three analysed attack scenarios created significant control impact and cost of disruption through turnarounds, avoidance manoeuvres, and diversions. They further increased workload, distrust in the affected system, and in 38% of cases caused the attacked safety system to be switched off entirely. All pilots felt the scenarios were useful, with 93.3% feeling that simulator training for wireless attacks could be valuable.

Date: 20 May 2019

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Privacy-Preserving P2P Energy Market on the Blockchain

Authors: Alain Brenzikofer, Noa Melchior

Abstract: Quartierstrom creates a peer-to-peer marketplace for locally generated solar power. The marketplace is implemented as a smart contract on a permissioned blockchain governed by all prosumers. Two privacy-by-design concepts are presented which guarantee that the users individual load profile is not leaked to any third party despite using a blockchain. The first approach leverages UTXO based coin mixing protocols in combination with an account-based on-chain smart contract. The second approach relies on an off-chain smart contract running in trusted execution environments.

Date: 20 May 2019

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Adaptive DDoS attack detection method based on multiple-kernel learning

Authors: Jieren Cheng, Chen Zhang, Xiangyan Tang, Victor S. Sheng, Zhe Dong, Junqi Li, Jing Chen

Abstract: Distributed denial of service (DDoS) attacks have caused huge economic losses to society. They have become one of the main threats to Internet security. Most of the current detection methods based on a single feature and fixed model parameters cannot effectively detect early DDoS attacks in cloud and big data environment. In this paper, an adaptive DDoS attack detection method (ADADM) based on multiple kernel learning (MKL) is proposed. Based on the burstiness of DDoS attack flow, the distribution of addresses and the interactivity of communication, we define five features to describe the network flow characteristic. Based on the ensemble learning framework, the weight of each dimension is adaptively adjusted by increasing the inter-class mean with a gradient ascent and reducing the intra-class variance with a gradient descent, and the classifier is established to identify an early DDoS attack by training simple multiple kernel learning (SMKL) models with two characteristics including inter-class mean squared difference growth (M-SMKL) and intra-class variance descent (S-SMKL). The sliding window mechanism is used to coordinate the S-SMKL and M-SMKL to detect the early DDoS attack. The experimental results indicate that this method can detect DDoS attacks early and accurately.

Date: 20 May 2019

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Improving security and bandwidth efficiency of NewHope using error-correction schemes

Authors: Minki Song, Seunghwan Lee, Eunsang Lee, Dong-Joon Shin, Young-Sik Kim, Jong-Seon No

Abstract: Among many submissions to the NIST post-quantum cryptography (PQC) project, NewHope is a promising key encapsulation mechanism (KEM) based on the Ring-Learning with errors (Ring-LWE) problem. Since the most important factors to be considered for PQC are security and cost including bandwidth and time/space complexity, in this paper, by doing exact noise analysis and using Bose Chaudhuri Hocquenghem (BCH) codes, it is shown that the security and bandwidth efficiency of NewHope can be substantially improved. In detail, the decryption failure rate (DFR) of NewHope is recalculated by performing exact noise analysis, and it is shown that the DFR of NewHope has been too conservatively calculated. Since the recalculated DFR is much lower than the required $2^{-128}$, this DFR margin is exploited to improve the security up to 8.5 \% or the bandwidth efficiency up to 5.9 \% without changing the procedure of NewHope. The additive threshold encoding (ATE) used in NewHope is a simple error correcting code (ECC) robust to side channel attack, but its error-correction capability is relatively weak compared with other ECCs. Therefore, if a proper error-correction scheme is applied to NewHope, either security or bandwidth efficiency or both can be improved. Among various ECCs, BCH code has been widely studied for its application to cryptosystems due to its advantages such as no error floor problem. In this paper, the ATE and total noise channel are regarded as a super channel from an information-theoretic viewpoint. Based on this super channel analysis, various concatenated coding schemes of ATE and BCH code for NewHope have been investigated. Through numerical analysis, it is revealed that the security and bandwidth efficiency of NewHope are substantially improved by using the proposed error-correction schemes.

Comment: 23 pages, 8 figures, Submission to AsiaCrypt 2019

Date: 20 May 2019

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Phish-IRIS: A New Approach for Vision Based Brand Prediction of Phishing Web Pages via Compact Visual Descriptors

Authors: Firat Coskun Dalgic, Ahmet Selman Bozkir, Murat Aydos

Abstract: Phishing, a continuously growing cyber threat, aims to obtain innocent users' credentials by deceiving them via presenting fake web pages which mimic their legitimate targets. To date, various attempts have been carried out in order to detect phishing pages. In this study, we treat the problem of phishing web page identification as an image classification task and propose a machine learning augmented pure vision based approach which extracts and classifies compact visual features from web page screenshots. For this purpose, we employed several MPEG7 and MPEG7-like compact visual descriptors (SCD, CLD, CEDD, FCTH and JCD) to reveal color and edge based discriminative visual cues. Throughout the feature extraction process we have followed two different schemes working on either whole screenshots in a "holistic" manner or equal sized "patches" constructing a coarse-to-fine "pyramidal" representation. Moreover, for the task of image classification, we have built SVM and Random Forest based machine learning models. In order to assess the performance and generalization capability of the proposed approach, we have collected a mid-sized corpus covering 14 distinct brands and involving 2852 samples. According to the conducted experiments, our approach reaches up to 90.5% F1 score via SCD. As a result, compared to other studies, the suggested approach presents a lightweight schema serving competitive accuracy and superior feature extraction and inferring speed that enables it to be used as a browser plugin.

Comment: 2nd International Symposium on Multidisciplinary Studies and Innovation Technologies, ISMSIT 2018

Date: 19 May 2019

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Toward Scalable Fully Homomorphic Encryption Through Light Trusted Computing Assistance

Authors: Wenhao Wang, Yichen Jiang, Qintao Shen, Weihao Huang, Hao Chen, Shuang Wang, XiaoFeng Wang, Haixu Tang, Kai Chen, Kristin Lauter, Dongdai Lin

Abstract: It has been a long standing problem to securely outsource computation tasks to an untrusted party with integrity and confidentiality guarantees. While fully homomorphic encryption (FHE) is a promising technique that allows computations performed on the encrypted data, it suffers from a significant slow down to the computation. In this paper we propose a hybrid solution that uses the latest hardware Trusted Execution Environments (TEEs) to assist FHE by moving the bootstrapping step, which is one of the major obstacles in designing practical FHE schemes, to a secured SGX enclave. TEEFHE, the hybrid system we designed, makes it possible for homomorphic computations to be performed on smaller ciphertext and secret key, providing better performance and lower memory consumption. We make an effort to mitigate side channel leakages within SGX by making the memory access patterns totally independent from the secret information. The evaluation shows that TEEFHE effectively improves the software only FHE schemes in terms of both time and space.

Date: 19 May 2019

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