Side Channel Attacks

06 April 2017, 14:00, Track 1

Session chair: Hoda A. Khezaimy, Emirates Advanced Investment Group, UAE

Securing Memory Encryption and Authentication Against Side-Channel Attacks Using Unprotected Primitives

Thomas Unterluggauer, Mario Werner, Stefan Mangard

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Memory encryption is used in many devices to protect memory content from attackers with physical access to a device. However, many current memory encryption schemes can be broken using Differential Power Analysis (DPA). In this work, we present MEAS—the first Memory Encryption and Authentication Scheme providing security against DPA attacks. The scheme combines ideas from fresh re-keying and authentication trees by storing encryption keys in a tree structure to thwart first-order DPA without the need for DPA-protected cryptographic primitives. Therefore, the design strictly limits the use of every key to encrypt at most two different plaintext values. MEAS prevents higher-order DPA without changes to the cipher implementation by using masking of the plaintext values. MEAS is applicable to all kinds of memory, e.g., NVM and RAM, and has memory overhead comparable to existing memory authentication techniques without DPA protection, e.g., 7.3% for a block size fitting standard disk sectors.

Don’t Skype & Type! Acoustic Eavesdropping in Voice-Over-IP

Alberto Compagno, Mauro Conti, Daniele Lain, Gene Tsudik

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Acoustic emanations of computer keyboards represent a serious privacy issue. As demonstrated in prior work, physical properties of keystroke sounds might reveal what a user is typing. However, previous attacks assumed relatively strong adversary models that are not very practical in many real-world settings. Such strong models assume: (i) adversary’s physical proximity to the victim, (ii) precise profiling of the victim’s typing style and keyboard, and/or (iii) significant amount of victim’s typed information (and its corresponding sounds) available to the adversary. This paper presents and explores a new keyboard acoustic eavesdropping attack that involves Voice-over-IP (VoIP), called Skype & Type (S&T), while avoiding prior strong adversary assumptions. This work is motivated by the simple observation that people often engage in secondary activities (including typing) while participating in VoIP calls. As expected, VoIP software acquires and faithfully transmits all sounds, including emanations of pressed keystrokes, which can include passwords and other sensitive information. We show that one very popular VoIP software (Skype) conveys enough audio information to reconstruct the victim’s input — keystrokes typed on the remote keyboard. Our results demonstrate that, given some knowledge on the victim’s typing style and keyboard model, the attacker attains top-5 accuracy of 91.7% in guessing a random key pressed by the victim. Furthermore, we demonstrate that S&T is robust to various VoIP issues (e.g., Internet bandwidth fluctuations and presence of voice over keystrokes), thus confirming feasibility of this attack. Finally, it applies to other popular VoIP software, such as Google Hangouts.

Hit by the Bus: QoS Degradation Attack on Android

Mehmet Sinan INCI, Thomas Eisenbarth, Berk Sunar

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Mobile apps need optimal performance and responsiveness to rise amongst numerous rivals on the market. Further, some apps like media streaming or gaming apps cannot even function properly with a performance below a certain threshold. In this work, we present the first performance degradation attack on Android OS that can target rival apps using a combination of logical channel leakages and low-level architectural bottlenecks in the underlying hardware. To show the viability of the attack, we design a proof-of-concept app and test it on various mobile platforms. The attack runs covertly and brings the target to the level of unresponsiveness. With less than 10% CPU time in the worst case, it requires minimal computational effort to run as a background service, and requires only the UsageStats permission from the user. We quantify the impact of our attack using 11 popular benchmark apps, running 44 different tests.} The measured QoS degradation varies across platforms and applications, reaching a maximum of 90\% in some cases. The attack combines the leakage from logical channels with low-level architectural bottlenecks to design a malicious app that can covertly degrade Quality of Service (QoS) of any targeted app. Furthermore, our attack code has a small footprint and is not detected by the Android system as malicious. Finally, our app can pass the Google Play Store malware scanner, Google Bouncer, as well as the top malware scanners in the Play Store.