Entries Tagged "side-channel attacks"

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Cell Phones Leak Location Information through Power Usage

New research on tracking the location of smart phone users by monitoring power consumption:

PowerSpy takes advantage of the fact that a phone’s cellular transmissions use more power to reach a given cell tower the farther it travels from that tower, or when obstacles like buildings or mountains block its signal. That correlation between battery use and variables like environmental conditions and cell tower distance is strong enough that momentary power drains like a phone conversation or the use of another power-hungry app can be filtered out, Michalevsky says.

One of the machine-learning tricks the researchers used to detect that “noise” is a focus on longer-term trends in the phone’s power use rather than those than last just a few seconds or minutes. “A sufficiently long power measurement (several minutes) enables the learning algorithm to ‘see’ through the noise,” the researchers write. “We show that measuring the phone’s aggregate power consumption over time completely reveals the phone’s location and movement.”

Even so, PowerSpy has a major limitation: It requires that the snooper pre-measure how a phone’s power use behaves as it travels along defined routes. This means you can’t snoop on a place you or a cohort has never been, as you need to have actually walked or driven along the route your subject’s phone takes in order to draw any location conclusions.

I’m not sure how practical this is, but it’s certainly interesting.

The paper.

Posted on February 23, 2015 at 10:30 AM • View Comments

Jumping Air Gaps with All-in-One Printers

Last week, Adi Shamir gave a presentation at Black Hat Europe on using all-in-one printers to control computers on the other side of air gaps. There’s no paper yet, but two publications reported on the talk:

Theoretically, if a malicious program is installed on an air-gapped computer by an unsuspecting user via, say, a USB thumb drive, attackers should have a hard time controlling the malicious program or stealing data through it because there is no Internet connection.

But the researchers found that if a multifunction printer is attached to such a computer, attackers could issue commands to a malicious program running on it by flashing visible or infrared light at the scanner lid when open.

[…]

The researchers observed that if a source of light is pointed repeatedly at the white coating on the inside of the scanner’s lid during a scanning operation, the resulting image will have a series of white lines on darker background. Those lines correspond to the pulses of light hitting the lid and their thickness depends on the duration of the pulses, Shamir explained.

Using this observation the researchers developed Morse code that can be used to send pulses of light at different intervals and interpret the resulting lines as binary data­1s and 0s. Malware running on an air-gapped system could be programmed to initiate a scanning operation at a certain time—for example, during the night—and then interpret the commands sent by attackers using the technique from far away.

Shamir estimated that several hundred bits of data can be sent during a single scan. That’s enough to send small commands that can activate various functionality built into the malware.

This technique can be used to send commands into an air-gapped computer network, and to exfiltrate data from that network.

Posted on October 22, 2014 at 2:17 PM • View Comments

Acoustic Cryptanalysis

This is neat:

Here, we describe a new acoustic cryptanalysis key extraction attack, applicable to GnuPG’s current implementation of RSA. The attack can extract full 4096-bit RSA decryption keys from laptop computers (of various models), within an hour, using the sound generated by the computer during the decryption of some chosen ciphertexts. We experimentally demonstrate that such attacks can be carried out, using either a plain mobile phone placed next to the computer, or a more sensitive microphone placed 4 meters away.

Beyond acoustics, we demonstrate that a similar low-bandwidth attack can be performed by measuring the electric potential of a computer chassis. A suitably-equipped attacker need merely touch the target computer with his bare hand, or get the required leakage information from the ground wires at the remote end of VGA, USB or Ethernet cables.

Posted on December 19, 2013 at 6:29 AM • View Comments

Breaking Hard-Disk Encryption

The newly announced ElcomSoft Forensic Disk Decryptor can decrypt BitLocker, PGP, and TrueCrypt. And it’s only $300. How does it work?

Elcomsoft Forensic Disk Decryptor acquires the necessary decryption keys by analyzing memory dumps and/or hibernation files obtained from the target PC. You’ll thus need to get a memory dump from a running PC (locked or unlocked) with encrypted volumes mounted, via a standard forensic product or via a FireWire attack. Alternatively, decryption keys can also be derived from hibernation files if a target PC is turned off.

This isn’t new. I wrote about AccessData doing the same thing in 2007:

Even so, none of this might actually matter. AccessData sells another program, Forensic Toolkit, that, among other things, scans a hard drive for every printable character string. It looks in documents, in the Registry, in e-mail, in swap files, in deleted space on the hard drive … everywhere. And it creates a dictionary from that, and feeds it into PRTK.

And PRTK breaks more than 50 percent of passwords from this dictionary alone.

It’s getting harder and harder to maintain good file security.

Posted on December 27, 2012 at 1:02 PM • View Comments

Stealing VM Keys from the Hardware Cache

Research into one VM stealing crypto keys from another VM running on the same hardware.

ABSTRACT: This paper details the construction of an access-driven side-channel attack by which a malicious virtual machine (VM) extracts fine-grained information from a victim VM running on the same physical computer. This attack is the first such attack demonstrated on a symmetric multiprocessing system virtualized using a modern VMM (Xen). Such systems are very common today, ranging from desktops that use virtualization to sandbox application or OS compromises, to clouds that co-locate the workloads of mutually distrustful customers. Constructing such a side-channel requires overcoming challenges including core migration, numerous sources of channel noise, and the difficulty of preempting the victim with sufficient frequency to extract fine-grained information from it. This paper addresses these challenges and demonstrates the attack in a lab setting by extracting an ElGamal decryption key from a victim using the most recent version of the libgcrypt cryptographic library.

Two articles.

Posted on November 16, 2012 at 6:13 AM • View Comments

Hacking Brain-Computer Interfaces

In this fascinating piece of research, the question is asked: can we surreptitiously collect secret information from the brains of people using brain-computer interface devices? One article:

A team of security researchers from Oxford, UC Berkeley, and the University of Geneva say that they were able to deduce digits of PIN numbers, birth months, areas of residence and other personal information by presenting 30 headset-wearing subjects with images of ATM machines, debit cards, maps, people, and random numbers in a series of experiments. The paper, titled “On the Feasibility of Side-Channel Attacks with Brain Computer Interfaces,” represents the first major attempt to uncover potential security risks in the use of the headsets.

This is a new development in spyware.

EDITED TO ADD (9/6): More articles. And here’s a discussion of the pros and cons of this sort of technology.

Posted on September 5, 2012 at 6:06 AM • View Comments

Can the NSA Break AES?

In an excellent article in Wired, James Bamford talks about the NSA’s codebreaking capability.

According to another top official also involved with the program, the NSA made an enormous breakthrough several years ago in its ability to cryptanalyze, or break, unfathomably complex encryption systems employed by not only governments around the world but also many average computer users in the US. The upshot, according to this official: “Everybody’s a target; everybody with communication is a target.”

Bamford has been writing about the NSA for decades, and people tell him all sorts of confidential things. Reading the above, the obvious question to ask is: can the NSA break AES?

My guess is that they can’t. That is, they don’t have a cryptanalytic attack against the AES algorithm that allows them to recover a key from known or chosen ciphertext with a reasonable time and memory complexity. I believe that what the “top official” was referring to is attacks that focus on the implementation and bypass the encryption algorithm: side-channel attacks, attacks against the key generation systems (either exploiting bad random number generators or sloppy password creation habits), attacks that target the endpoints of the communication system and not the wire, attacks that exploit key leakage, attacks against buggy implementations of the algorithm, and so on. These attacks are likely to be much more effective against computer encryption.

EDITED TO ADD (3/22): Another option is that the NSA has built dedicated hardware capable of factoring 1024-bit numbers. There’s quite a lot of RSA-1024 out there, so that would be a fruitful project. So, maybe.

EDITED TO ADD (4/13): The NSA denies everything.

Posted on March 22, 2012 at 7:17 AM • View Comments

Improving the Security of Four-Digit PINs on Cell Phones

The author of this article notices that it’s often easy to guess a cell phone PIN because of smudge marks on the screen. Those smudge marks indicate the four PIN digits, so an attacker knows that the PIN is one of 24 possible permutations of those digits.

Then he points out that if your PIN has only three different digits—1231, for example—the PIN can be one of 36 different possibilities.

So it’s more security, although not much more secure.

Posted on January 6, 2012 at 6:30 AM • View Comments

Smartphone Keystroke Logging Using the Motion Sensor

Clever:

“When the user types on the soft keyboard on her smartphone (especially when she holds her phone by hand rather than placing it on a fixed surface), the phone vibrates. We discover that keystroke vibration on touch screens are highly correlated to the keys being typed.”

Applications like TouchLogger could be significant because they bypass protections built into both Android and Apple’s competing iOS that prevent a program from reading keystrokes unless it’s active and receives focus from the screen. It was designed to work on an HTC Evo 4G smartphone. It had an accuracy rate of more than 70 percent of the input typed into the number-only soft keyboard of the device. The app worked by using the phone’s accelerometer to gauge the motion of the device each time a soft key was pressed.

Paper here. More articles.

Posted on August 23, 2011 at 2:09 PM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.