Entries Tagged "side-channel attacks"

Page 4 of 8

Eavesdropping on Typing Over Voice-Over-IP

Interesting research: “Don’t Skype & Type! Acoustic Eavesdropping in Voice-Over-IP“:

Abstract: Acoustic emanations of computer keyboards represent a serious privacy issue. As demonstrated in prior work, spectral and temporal 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.

In this paper, we investigate a new and practical keyboard acoustic eavesdropping attack, called Skype & Type (S&T), which is based on Voice-over-IP (VoIP). S&T relaxes prior strong adversary assumptions. Our work is motivated by the simple observation that people often engage in secondary activities (including typing) while participating in VoIP calls. VoIP software can acquire acoustic emanations of pressed keystrokes (which might include passwords and other sensitive information) and transmit them to others involved in the call. In fact, we show that very popular VoIP software (Skype) conveys enough audio information to reconstruct the victim’s input ­ keystrokes typed on the remote keyboard. In particular, our results demonstrate
that, given some knowledge on the victim’s typing style and the keyboard, the attacker attains top-5 accuracy of 91:7% in guessing a random key pressed by the victim. (The accuracy goes down to still alarming 41:89% if the attacker is oblivious to both the typing style and the keyboard). Finally, we provide evidence that Skype & Type attack is robust to various VoIP issues (e.g., Internet bandwidth fluctuations and presence of voice over keystrokes), thus confirming feasibility of this attack.

News article.

Posted on October 28, 2016 at 5:24 AMView Comments

Keystroke Recognition from Wi-Fi Distortion

This is interesting research: “Keystroke Recognition Using WiFi Signals.” Basically, the user’s hand positions as they type distorts the Wi-Fi signal in predictable ways.

Abstract: Keystroke privacy is critical for ensuring the security of computer systems and the privacy of human users as what being typed could be passwords or privacy sensitive information. In this paper, we show for the first time that WiFi signals
can also be exploited to recognize keystrokes. The intuition is that while typing a certain key, the hands and fingers of a user move in a unique formation and direction and thus generate a unique pattern in the time-series of Channel State Information (CSI) values, which we call CSI-waveform for that key. In this paper, we propose a WiFi signal based keystroke recognition system called WiKey. WiKey consists of two Commercial Off-The-Shelf (COTS) WiFi devices, a sender (such as a router) and a receiver (such as a laptop). The sender continuously emits signals and the receiver continuously receives signals. When a human subject types on a keyboard, WiKey recognizes the typed keys based on how the CSI values at the WiFi signal receiver end. We implemented the WiKey system using a TP-Link TL-WR1043ND WiFi router and a Lenovo X200 laptop. WiKey achieves more than 97.5% detection rate for detecting the keystroke and 96.4% recognition accuracy for classifying single keys. In real-world experiments, WiKey can recognize keystrokes in a continuously typed sentence with an accuracy of 93.5%.

News article.

Posted on August 30, 2016 at 6:04 AMView Comments

Hacking Electronic Safes

Nice attack against electronic safes:

Plore used side-channel attacks to pull it off. These are ways of exploiting physical indicators from a cryptographic system to get around its protections. Here, all Plore had to do was monitor power consumption in the case of one safe, and the amount of time operations took in other, and voila, he was able to figure out the keycodes for locks that are designated by independent third-party testing company Underwriter’s Laboratory as Type 1 High Security. These aren’t the most robust locks on the market by any means, but they are known to be pretty secure. Safes with these locks are the kind of thing you might have in your house.

Posted on August 12, 2016 at 6:52 AMView Comments

Practical TEMPEST Attack

Four researchers have demonstrated a TEMPEST attack against a laptop, recovering its keys by listening to its electrical emanations. The cost for the attack hardware was about $3,000.

News article:

To test the hack, the researchers first sent the target a specific ciphertext—­in other words, an encrypted message.

“During the decryption of the chosen ciphertext, we measure the EM leakage of the target laptop, focusing on a narrow frequency band,” the paper reads. The signal is then processed, and “a clean trace is produced which reveals information about the operands used in the elliptic curve cryptography,” it continues, which in turn “is used in order to reveal the secret key.”

The equipment used included an antenna, amplifiers, a software-defined radio, and a laptop. This process was being carried out through a 15cm thick wall, reinforced with metal studs, according to the paper.

The researchers obtained the secret key after observing 66 decryption processes, each lasting around 0.05 seconds. “This yields a total measurement time of about 3.3 sec,” the paper reads. It’s important to note that when the researchers say that the secret key was obtained in “seconds,” that’s the total measurement time, and not necessarily how long it would take for the attack to actually be carried out. A real world attacker would still need to factor in other things, such as the target reliably decrypting the sent ciphertext, because observing that process is naturally required for the attack to be successful.

For half a century this has been a nation-state-level espionage technique. The cost is continually falling.

Posted on February 23, 2016 at 5:49 AMView Comments


There’s a new paper on a low-cost TEMPEST attack against PC cryptography:

We demonstrate the extraction of secret decryption keys from laptop computers, by nonintrusively measuring electromagnetic emanations for a few seconds from a distance of 50 cm. The attack can be executed using cheap and readily-available equipment: a consumer-grade radio receiver or a Software Defined Radio USB dongle. The setup is compact and can operate untethered; it can be easily concealed, e.g., inside pita bread. Common laptops, and popular implementations of RSA and ElGamal encryptions, are vulnerable to this attack, including those that implement the decryption using modern exponentiation algorithms such as sliding-window, or even its side-channel resistant variant, fixed-window (m-ary) exponentiation.

We successfully extracted keys from laptops of various models running GnuPG (popular open source encryption software, implementing the OpenPGP standard), within a few seconds. The attack sends a few carefully-crafted ciphertexts, and when these are decrypted by the target computer, they trigger the occurrence of specially-structured values inside the decryption software. These special values cause observable fluctuations in the electromagnetic field surrounding the laptop, in a way that depends on the pattern of key bits (specifically, the key-bits window in the exponentiation routine). The secret key can be deduced from these fluctuations, through signal processing and cryptanalysis.

From Wired:

Researchers at Tel Aviv University and Israel’s Technion research institute have developed a new palm-sized device that can wirelessly steal data from a nearby laptop based on the radio waves leaked by its processor’s power use. Their spy bug, built for less than $300, is designed to allow anyone to “listen” to the accidental radio emanations of a computer’s electronics from 19 inches away and derive the user’s secret decryption keys, enabling the attacker to read their encrypted communications. And that device, described in a paper they’re presenting at the Workshop on Cryptographic Hardware and Embedded Systems in September, is both cheaper and more compact than similar attacks from the past—so small, in fact, that the Israeli researchers demonstrated it can fit inside a piece of pita bread.

Another article. NSA article from 1972 on TEMPEST. Hacker News thread. Reddit thread.

Posted on June 29, 2015 at 1:38 PMView Comments

Tracking People By Smart Phone Accelerometers

Interesting research: “We Can Track You If You Take the Metro: Tracking Metro Riders Using Accelerometers on Smartphones“:

Abstract: Motion sensors (e.g., accelerometers) on smartphones have been demonstrated to be a powerful side channel for attackers to spy on users’ inputs on touchscreen. In this paper, we reveal another motion accelerometer-based attack which is particularly serious: when a person takes the metro, a malicious application on her smartphone can easily use accelerator readings to trace her. We first propose a basic attack that can automatically extract metro-related data from a large amount of mixed accelerator readings, and then use an ensemble interval classier built from supervised learning to infer the riding intervals of the user. While this attack is very effective, the supervised learning part requires the attacker to collect labeled training data for each station interval, which is a significant amount of effort. To improve the efficiency of our attack, we further propose a semi-supervised learning approach, which only requires the attacker to collect labeled data for a very small number of station intervals with obvious characteristics. We conduct real experiments on a metro line in a major city. The results show that the inferring accuracy could reach 89% and 92% if the user takes the metro for 4 and 6 stations, respectively.

The Internet of Things is the Internet of sensors. I’m sure all kinds of surveillance is possible from all kinds of sensing inputs.

Posted on June 8, 2015 at 6:09 AMView Comments

Easily Cracking a Master Combination Lock


Kamkar told Ars his Master Lock exploit started with a well-known vulnerability that allows Master Lock combinations to be cracked in 100 or fewer tries. He then physically broke open a combination lock and noticed the resistance he observed was caused by two lock parts that touched in a way that revealed important clues about the combination. (He likened the Master Lock design to a side channel in cryptographic devices that can be exploited to obtain the secret key.) Kamkar then made a third observation that was instrumental to his Master Lock exploit: the first and third digit of the combination, when divided by four, always return the same remainder. By combining the insights from all three weaknesses he devised the attack laid out in the video.

Posted on May 5, 2015 at 6:59 AMView Comments

Sidebar photo of Bruce Schneier by Joe MacInnis.