Entries Tagged "academic papers"

Page 29 of 86

Another Branch Prediction Attack

When Spectre and Meltdown were first announced earlier this year, pretty much everyone predicted that there would be many more attacks targeting branch prediction in microprocessors. Here’s another one:

In the new attack, an attacker primes the PHT and running branch instructions so that the PHT will always assume a particular branch is taken or not taken. The victim code then runs and makes a branch, which is potentially disturbing the PHT. The attacker then runs more branch instructions of its own to detect that disturbance to the PHT; the attacker knows that some branches should be predicted in a particular direction and tests to see if the victim’s code has changed that prediction.

The researchers looked only at Intel processors, using the attacks to leak information protected using Intel’s SGX (Software Guard Extensions), a feature found on certain chips to carve out small sections of encrypted code and data such that even the operating system (or virtualization software) cannot access it. They also described ways the attack could be used against address space layout randomization and to infer data in encryption and image libraries.

Research paper.

Posted on March 29, 2018 at 6:23 AM • View Comments

Tracing Stolen Bitcoin

Ross Anderson has a really interesting paper on tracing stolen bitcoin. From a blog post:

Previous attempts to track tainted coins had used either the “poison” or the “haircut” method. Suppose I open a new address and pay into it three stolen bitcoin followed by seven freshly-mined ones. Then under poison, the output is ten stolen bitcoin, while under haircut it’s ten bitcoin that are marked 30% stolen. After thousands of blocks, poison tainting will blacklist millions of addresses, while with haircut the taint gets diffused, so neither is very effective at tracking stolen property. Bitcoin due-diligence services supplant haircut taint tracking with AI/ML, but the results are still not satisfactory.

We discovered that, back in 1816, the High Court had to tackle this problem in Clayton’s case, which involved the assets and liabilities of a bank that had gone bust. The court ruled that money must be tracked through accounts on the basis of first-in, first out (FIFO); the first penny into an account goes to satisfy the first withdrawal, and so on.

Ilia Shumailov has written software that applies FIFO tainting to the blockchain and the results are impressive, with a massive improvement in precision. What’s more, FIFO taint tracking is lossless, unlike haircut; so in addition to tracking a stolen coin forward to find where it’s gone, you can start with any UTXO and trace it backwards to see its entire ancestry. It’s not just good law; it’s good computer science too.

Posted on March 28, 2018 at 6:30 AM •

Adding Backdoors at the Chip Level

Interesting research into undetectably adding backdoors into computer chips during manufacture: “Stealthy dopant-level hardware Trojans: extended version,” also available here:

Abstract: In recent years, hardware Trojans have drawn the attention of governments and industry as well as the scientific community. One of the main concerns is that integrated circuits, e.g., for military or critical-infrastructure applications, could be maliciously manipulated during the manufacturing process, which often takes place abroad. However, since there have been no reported hardware Trojans in practice yet, little is known about how such a Trojan would look like and how difficult it would be in practice to implement one. In this paper we propose an extremely stealthy approach for implementing hardware Trojans below the gate level, and we evaluate their impact on the security of the target device. Instead of adding additional circuitry to the target design, we insert our hardware Trojans by changing the dopant polarity of existing transistors. Since the modified circuit appears legitimate on all wiring layers (including all metal and polysilicon), our family of Trojans is resistant to most detection techniques, including fine-grain optical inspection and checking against “golden chips”. We demonstrate the effectiveness of our approach by inserting Trojans into two designs—a digital post-processing derived from Intel’s cryptographically secure RNG design used in the Ivy Bridge processors and a side-channel resistant SBox implementation­—and by exploring their detectability and their effects on security.

The moral is that this kind of technique is very difficult to detect.

EDITED TO ADD (4/13): Apologies. I didn’t realize that this paper was from 2014.

Posted on March 26, 2018 at 9:26 AM • View Comments

Hijacking Computers for Cryptocurrency Mining

Interesting paper “A first look at browser-based cryptojacking“:

Abstract: In this paper, we examine the recent trend towards in-browser mining of cryptocurrencies; in particular, the mining of Monero through Coinhive and similar code-bases. In this model, a user visiting a website will download a JavaScript code that executes client-side in her browser, mines a cryptocurrency, typically without her consent or knowledge, and pays out the seigniorage to the website. Websites may consciously employ this as an alternative or to supplement advertisement revenue, may offer premium content in exchange for mining, or may be unwittingly serving the code as a result of a breach (in which case the seigniorage is collected by the attacker). The cryptocurrency Monero is preferred seemingly for its unfriendliness to large-scale ASIC mining that would drive browser-based efforts out of the market, as well as for its purported privacy features. In this paper, we survey this landscape, conduct some measurements to establish its prevalence and profitability, outline an ethical framework for considering whether it should be classified as an attack or business opportunity, and make suggestions for the detection, mitigation and/or prevention of browser-based mining for non-consenting users.

Posted on March 21, 2018 at 6:27 AM • View Comments

Two New Papers on the Encryption Debate

Seems like everyone is writing about encryption and backdoors this season.

I recently blogged about the new National Academies report on the same topic.

Here’s a review of the National Academies report, and another of the East West Institute’s report.

EDITED TO ADD (3/8): Commentary on the National Academies study by the EFF.

Posted on March 12, 2018 at 6:27 AM • View Comments

Security Vulnerabilities in Smart Contracts

Interesting research: “Finding The Greedy, Prodigal, and Suicidal Contracts at Scale“:

Abstract: Smart contracts—stateful executable objects hosted on blockchains like Ethereum—carry billions of dollars worth of coins and cannot be updated once deployed. We present a new systematic characterization of a class of trace vulnerabilities, which result from analyzing multiple invocations of a contract over its lifetime. We focus attention on three example properties of such trace vulnerabilities: finding contracts that either lock funds indefinitely, leak them carelessly to arbitrary users, or can be killed by anyone. We implemented MAIAN, the first tool for precisely specifying and reasoning about trace properties, which employs inter-procedural symbolic analysis and concrete validator for exhibiting real exploits. Our analysis of nearly one million contracts flags 34,200 (2,365 distinct) contracts vulnerable, in 10 seconds per contract. On a subset of 3,759 contracts which we sampled for concrete validation and manual analysis, we reproduce real exploits at a true positive rate of 89%, yielding exploits for 3,686 contracts. Our tool finds exploits for the infamous Parity bug that indirectly locked 200 million dollars worth in Ether, which previous analyses failed to capture.

Posted on March 6, 2018 at 6:18 AM • View Comments

Extracting Secrets from Machine Learning Systems

This is fascinating research about how the underlying training data for a machine-learning system can be inadvertently exposed. Basically, if a machine-learning system trains on a dataset that contains secret information, in some cases an attacker can query the system to extract that secret information. My guess is that there is a lot more research to be done here.

EDITED TO ADD (3/9): Some interesting links on the subject.

Posted on March 5, 2018 at 5:20 AM • View Comments

Malware from Space

Since you don’t have enough to worry about, here’s a paper postulating that space aliens could send us malware capable of destroying humanity.

Abstract: A complex message from space may require the use of computers to display, analyze and understand. Such a message cannot be decontaminated with certainty, and technical risks remain which can pose an existential threat. Complex messages would need to be destroyed in the risk averse case.

I think we’re more likely to be enslaved by malicious AIs.

Posted on March 2, 2018 at 6:13 AM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.