Entries Tagged "machine learning"

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Bots Are Better than Humans at Solving CAPTCHAs

Interesting research: “An Empirical Study & Evaluation of Modern CAPTCHAs“:

Abstract: For nearly two decades, CAPTCHAS have been widely used as a means of protection against bots. Throughout the years, as their use grew, techniques to defeat or bypass CAPTCHAS have continued to improve. Meanwhile, CAPTCHAS have also evolved in terms of sophistication and diversity, becoming increasingly difficult to solve for both bots (machines) and humans. Given this long-standing and still-ongoing arms race, it is critical to investigate how long it takes legitimate users to solve modern CAPTCHAS, and how they are perceived by those users.

In this work, we explore CAPTCHAS in the wild by evaluating users’ solving performance and perceptions of unmodified currently-deployed CAPTCHAS. We obtain this data through manual inspection of popular websites and user studies in which 1, 400 participants collectively solved 14, 000 CAPTCHAS. Results show significant differences between the most popular types of CAPTCHAS: surprisingly, solving time and user perception are not always correlated. We performed a comparative study to investigate the effect of experimental context ­ specifically the difference between solving CAPTCHAS directly versus solving them as part of a more natural task, such as account creation. Whilst there were several potential confounding factors, our results show that experimental context could have an impact on this task, and must be taken into account in future CAPTCHA studies. Finally, we investigate CAPTCHA-induced user task abandonment by analyzing participants who start and do not complete the task.

Slashdot thread.

And let’s all rewatch this great ad from 2022.

Posted on August 18, 2023 at 7:04 AM • View Comments

Using Machine Learning to Detect Keystrokes

Researchers have trained a ML model to detect keystrokes by sound with 95% accuracy.

“A Practical Deep Learning-Based Acoustic Side Channel Attack on Keyboards”

Abstract: With recent developments in deep learning, the ubiquity of microphones and the rise in online services via personal devices, acoustic side channel attacks present a greater threat to keyboards than ever. This paper presents a practical implementation of a state-of-the-art deep learning model in order to classify laptop keystrokes, using a smartphone integrated microphone. When trained on keystrokes recorded by a nearby phone, the classifier achieved an accuracy of 95%, the highest accuracy seen without the use of a language model. When trained on keystrokes recorded using the video-conferencing software Zoom, an accuracy of 93% was achieved, a new best for the medium. Our results prove the practicality of these side channel attacks via off-the-shelf equipment and algorithms. We discuss a series of mitigation methods to protect users against these series of attacks.

News article.

Posted on August 9, 2023 at 7:08 AM • View Comments

Indirect Instruction Injection in Multi-Modal LLMs

Interesting research: “(Ab)using Images and Sounds for Indirect Instruction Injection in Multi-Modal LLMs”:

Abstract: We demonstrate how images and sounds can be used for indirect prompt and instruction injection in multi-modal LLMs. An attacker generates an adversarial perturbation corresponding to the prompt and blends it into an image or audio recording. When the user asks the (unmodified, benign) model about the perturbed image or audio, the perturbation steers the model to output the attacker-chosen text and/or make the subsequent dialog follow the attacker’s instruction. We illustrate this attack with several proof-of-concept examples targeting LLaVa and PandaGPT.

Posted on July 28, 2023 at 7:06 AM • View Comments

Security Risks of AI

Stanford and Georgetown have a new report on the security risks of AI—particularly adversarial machine learning—based on a workshop they held on the topic.

Jim Dempsey, one of the workshop organizers, wrote a blog post on the report:

As a first step, our report recommends the inclusion of AI security concerns within the cybersecurity programs of developers and users. The understanding of how to secure AI systems, we concluded, lags far behind their widespread adoption. Many AI products are deployed without institutions fully understanding the security risks they pose. Organizations building or deploying AI models should incorporate AI concerns into their cybersecurity functions using a risk management framework that addresses security throughout the AI system life cycle. It will be necessary to grapple with the ways in which AI vulnerabilities are different from traditional cybersecurity bugs, but the starting point is to assume that AI security is a subset of cybersecurity and to begin applying vulnerability management practices to AI-based features. (Andy Grotto and I have vigorously argued against siloing AI security in its own governance and policy vertical.)

Our report also recommends more collaboration between cybersecurity practitioners, machine learning engineers, and adversarial machine learning researchers. Assessing AI vulnerabilities requires technical expertise that is distinct from the skill set of cybersecurity practitioners, and organizations should be cautioned against repurposing existing security teams without additional training and resources. We also note that AI security researchers and practitioners should consult with those addressing AI bias. AI fairness researchers have extensively studied how poor data, design choices, and risk decisions can produce biased outcomes. Since AI vulnerabilities may be more analogous to algorithmic bias than they are to traditional software vulnerabilities, it is important to cultivate greater engagement between the two communities.

Another major recommendation calls for establishing some form of information sharing among AI developers and users. Right now, even if vulnerabilities are identified or malicious attacks are observed, this information is rarely transmitted to others, whether peer organizations, other companies in the supply chain, end users, or government or civil society observers. Bureaucratic, policy, and cultural barriers currently inhibit such sharing. This means that a compromise will likely remain mostly unnoticed until long after attackers have successfully exploited vulnerabilities. To avoid this outcome, we recommend that organizations developing AI models monitor for potential attacks on AI systems, create—formally or informally—a trusted forum for incident information sharing on a protected basis, and improve transparency.

Posted on April 27, 2023 at 9:38 AM • View Comments

Using LLMs to Create Bioweapons

I’m not sure there are good ways to build guardrails to prevent this sort of thing:

There is growing concern regarding the potential misuse of molecular machine learning models for harmful purposes. Specifically, the dual-use application of models for predicting cytotoxicity18 to create new poisons or employing AlphaFold2 to develop novel bioweapons has raised alarm. Central to these concerns are the possible misuse of large language models and automated experimentation for dual-use purposes or otherwise. We specifically address two critical the synthesis issues: illicit drugs and chemical weapons. To evaluate these risks, we designed a test set comprising compounds from the DEA’s Schedule I and II substances and a list of known chemical weapon agents. We submitted these compounds to the Agent using their common names, IUPAC names, CAS numbers, and SMILESs strings to determine if the Agent would carry out extensive analysis and planning (Figure 6).

[…]

The run logs can be found in Appendix F. Out of 11 different prompts (Figure 6), four (36%) provided a synthesis solution and attempted to consult documentation to execute the procedure. This figure is alarming on its own, but an even greater concern is the way in which the Agent declines to synthesize certain threats. Out of the seven refused chemicals, five were rejected after the Agent utilized search functions to gather more information about the substance. For instance, when asked about synthesizing codeine, the Agent becomes alarmed upon learning the connection between codeine and morphine, only then concluding that the synthesis cannot be conducted due to the requirement of a controlled substance. However, this search function can be easily manipulated by altering the terminology, such as replacing all mentions of morphine with “Compound A” and codeine with “Compound B”. Alternatively, when requesting a b synthesis procedure that must be performed in a DEA-licensed facility, bad actors can mislead the Agent by falsely claiming their facility is licensed, prompting the Agent to devise a synthesis solution.

In the remaining two instances, the Agent recognized the common names “heroin” and “mustard gas” as threats and prevented further information gathering. While these results are promising, it is crucial to recognize that the system’s capacity to detect misuse primarily applies to known compounds. For unknown compounds, the model is less likely to identify potential misuse, particularly for complex protein toxins where minor sequence changes might allow them to maintain the same properties but become unrecognizable to the model.

Posted on April 18, 2023 at 7:19 AM • View Comments

LLMs and Phishing

Here’s an experiment being run by undergraduate computer science students everywhere: Ask ChatGPT to generate phishing emails, and test whether these are better at persuading victims to respond or click on the link than the usual spam. It’s an interesting experiment, and the results are likely to vary wildly based on the details of the experiment.

But while it’s an easy experiment to run, it misses the real risk of large language models (LLMs) writing scam emails. Today’s human-run scams aren’t limited by the number of people who respond to the initial email contact. They’re limited by the labor-intensive process of persuading those people to send the scammer money. LLMs are about to change that. A decade ago, one type of spam email had become a punchline on every late-night show: “I am the son of the late king of Nigeria in need of your assistance….” Nearly everyone had gotten one or a thousand of those emails, to the point that it seemed everyone must have known they were scams.

So why were scammers still sending such obviously dubious emails? In 2012, researcher Cormac Herley offered an answer: It weeded out all but the most gullible. A smart scammer doesn’t want to waste their time with people who reply and then realize it’s a scam when asked to wire money. By using an obvious scam email, the scammer can focus on the most potentially profitable people. It takes time and effort to engage in the back-and-forth communications that nudge marks, step by step, from interlocutor to trusted acquaintance to pauper.

Long-running financial scams are now known as pig butchering, growing the potential mark up until their ultimate and sudden demise. Such scams, which require gaining trust and infiltrating a target’s personal finances, take weeks or even months of personal time and repeated interactions. It’s a high stakes and low probability game that the scammer is playing.

Here is where LLMs will make a difference. Much has been written about the unreliability of OpenAI’s GPT models and those like them: They “hallucinate” frequently, making up things about the world and confidently spouting nonsense. For entertainment, this is fine, but for most practical uses it’s a problem. It is, however, not a bug but a feature when it comes to scams: LLMs’ ability to confidently roll with the punches, no matter what a user throws at them, will prove useful to scammers as they navigate hostile, bemused, and gullible scam targets by the billions. AI chatbot scams can ensnare more people, because the pool of victims who will fall for a more subtle and flexible scammer—one that has been trained on everything ever written online—is much larger than the pool of those who believe the king of Nigeria wants to give them a billion dollars.

Personal computers are powerful enough today that they can run compact LLMs. After Facebook’s new model, LLaMA, was leaked online, developers tuned it to run fast and cheaply on powerful laptops. Numerous other open-source LLMs are under development, with a community of thousands of engineers and scientists.

A single scammer, from their laptop anywhere in the world, can now run hundreds or thousands of scams in parallel, night and day, with marks all over the world, in every language under the sun. The AI chatbots will never sleep and will always be adapting along their path to their objectives. And new mechanisms, from ChatGPT plugins to LangChain, will enable composition of AI with thousands of API-based cloud services and open source tools, allowing LLMs to interact with the internet as humans do. The impersonations in such scams are no longer just princes offering their country’s riches. They are forlorn strangers looking for romance, hot new cryptocurrencies that are soon to skyrocket in value, and seemingly-sound new financial websites offering amazing returns on deposits. And people are already falling in love with LLMs.

This is a change in both scope and scale. LLMs will change the scam pipeline, making them more profitable than ever. We don’t know how to live in a world with a billion, or 10 billion, scammers that never sleep.

There will also be a change in the sophistication of these attacks. This is due not only to AI advances, but to the business model of the internet—surveillance capitalism—which produces troves of data about all of us, available for purchase from data brokers. Targeted attacks against individuals, whether for phishing or data collection or scams, were once only within the reach of nation-states. Combine the digital dossiers that data brokers have on all of us with LLMs, and you have a tool tailor-made for personalized scams.

Companies like OpenAI attempt to prevent their models from doing bad things. But with the release of each new LLM, social media sites buzz with new AI jailbreaks that evade the new restrictions put in place by the AI’s designers. ChatGPT, and then Bing Chat, and then GPT-4 were all jailbroken within minutes of their release, and in dozens of different ways. Most protections against bad uses and harmful output are only skin-deep, easily evaded by determined users. Once a jailbreak is discovered, it usually can be generalized, and the community of users pulls the LLM open through the chinks in its armor. And the technology is advancing too fast for anyone to fully understand how they work, even the designers.

This is all an old story, though: It reminds us that many of the bad uses of AI are a reflection of humanity more than they are a reflection of AI technology itself. Scams are nothing new—simply intent and then action of one person tricking another for personal gain. And the use of others as minions to accomplish scams is sadly nothing new or uncommon: For example, organized crime in Asia currently kidnaps or indentures thousands in scam sweatshops. Is it better that organized crime will no longer see the need to exploit and physically abuse people to run their scam operations, or worse that they and many others will be able to scale up scams to an unprecedented level?

Defense can and will catch up, but before it does, our signal-to-noise ratio is going to drop dramatically.

This essay was written with Barath Raghavan, and previously appeared on Wired.com.

Posted on April 10, 2023 at 7:23 AM • View Comments

Side-Channel Attack against CRYSTALS-Kyber

CRYSTALS-Kyber is one of the public-key algorithms currently recommended by NIST as part of its post-quantum cryptography standardization process.

Researchers have just published a side-channel attack—using power consumption—against an implementation of the algorithm that was supposed to be resistant against that sort of attack.

The algorithm is not “broken” or “cracked”—despite headlines to the contrary—this is just a side-channel attack. What makes this work really interesting is that the researchers used a machine-learning model to train the system to exploit the side channel.

Posted on February 28, 2023 at 7:19 AM • View Comments

Putting Undetectable Backdoors in Machine Learning Models

This is really interesting research from a few months ago:

Abstract: Given the computational cost and technical expertise required to train machine learning models, users may delegate the task of learning to a service provider. Delegation of learning has clear benefits, and at the same time raises serious concerns of trust. This work studies possible abuses of power by untrusted learners.We show how a malicious learner can plant an undetectable backdoor into a classifier. On the surface, such a backdoored classifier behaves normally, but in reality, the learner maintains a mechanism for changing the classification of any input, with only a slight perturbation. Importantly, without the appropriate “backdoor key,” the mechanism is hidden and cannot be detected by any computationally-bounded observer. We demonstrate two frameworks for planting undetectable backdoors, with incomparable guarantees.

First, we show how to plant a backdoor in any model, using digital signature schemes. The construction guarantees that given query access to the original model and the backdoored version, it is computationally infeasible to find even a single input where they differ. This property implies that the backdoored model has generalization error comparable with the original model. Moreover, even if the distinguisher can request backdoored inputs of its choice, they cannot backdoor a new input­a property we call non-replicability.

Second, we demonstrate how to insert undetectable backdoors in models trained using the Random Fourier Features (RFF) learning paradigm (Rahimi, Recht; NeurIPS 2007). In this construction, undetectability holds against powerful white-box distinguishers: given a complete description of the network and the training data, no efficient distinguisher can guess whether the model is “clean” or contains a backdoor. The backdooring algorithm executes the RFF algorithm faithfully on the given training data, tampering only with its random coins. We prove this strong guarantee under the hardness of the Continuous Learning With Errors problem (Bruna, Regev, Song, Tang; STOC 2021). We show a similar white-box undetectable backdoor for random ReLU networks based on the hardness of Sparse PCA (Berthet, Rigollet; COLT 2013).

Our construction of undetectable backdoors also sheds light on the related issue of robustness to adversarial examples. In particular, by constructing undetectable backdoor for an “adversarially-robust” learning algorithm, we can produce a classifier that is indistinguishable from a robust classifier, but where every input has an adversarial example! In this way, the existence of undetectable backdoors represent a significant theoretical roadblock to certifying adversarial robustness.

Turns out that securing ML systems is really hard.

Posted on February 24, 2023 at 7:34 AM • View Comments

Attacking Machine Learning Systems

The field of machine learning (ML) security—and corresponding adversarial ML—is rapidly advancing as researchers develop sophisticated techniques to perturb, disrupt, or steal the ML model or data. It’s a heady time; because we know so little about the security of these systems, there are many opportunities for new researchers to publish in this field. In many ways, this circumstance reminds me of the cryptanalysis field in the 1990. And there is a lesson in that similarity: the complex mathematical attacks make for good academic papers, but we mustn’t lose sight of the fact that insecure software will be the likely attack vector for most ML systems.

We are amazed by real-world demonstrations of adversarial attacks on ML systems, such as a 3D-printed object that looks like a turtle but is recognized (from any orientation) by the ML system as a gun. Or adding a few stickers that look like smudges to a stop sign so that it is recognized by a state-of-the-art system as a 45 mi/h speed limit sign. But what if, instead, somebody hacked into the system and just switched the labels for “gun” and “turtle” or swapped “stop” and “45 mi/h”? Systems can only match images with human-provided labels, so the software would never notice the switch. That is far easier and will remain a problem even if systems are developed that are robust to those adversarial attacks.

At their core, modern ML systems have complex mathematical models that use training data to become competent at a task. And while there are new risks inherent in the ML model, all of that complexity still runs in software. Training data are still stored in memory somewhere. And all of that is on a computer, on a network, and attached to the Internet. Like everything else, these systems will be hacked through vulnerabilities in those more conventional parts of the system.

This shouldn’t come as a surprise to anyone who has been working with Internet security. Cryptography has similar vulnerabilities. There is a robust field of cryptanalysis: the mathematics of code breaking. Over the last few decades, we in the academic world have developed a variety of cryptanalytic techniques. We have broken ciphers we previously thought secure. This research has, in turn, informed the design of cryptographic algorithms. The classified world of the NSA and its foreign counterparts have been doing the same thing for far longer. But aside from some special cases and unique circumstances, that’s not how encryption systems are exploited in practice. Outside of academic papers, cryptosystems are largely bypassed because everything around the cryptography is much less secure.

I wrote this in my book, Data and Goliath:

The problem is that encryption is just a bunch of math, and math has no agency. To turn that encryption math into something that can actually provide some security for you, it has to be written in computer code. And that code needs to run on a computer: one with hardware, an operating system, and other software. And that computer needs to be operated by a person and be on a network. All of those things will invariably introduce vulnerabilities that undermine the perfection of the mathematics…

This remains true even for pretty weak cryptography. It is much easier to find an exploitable software vulnerability than it is to find a cryptographic weakness. Even cryptographic algorithms that we in the academic community regard as “broken”—meaning there are attacks that are more efficient than brute force—are usable in the real world because the difficulty of breaking the mathematics repeatedly and at scale is much greater than the difficulty of breaking the computer system that the math is running on.

ML systems are similar. Systems that are vulnerable to model stealing through the careful construction of queries are more vulnerable to model stealing by hacking into the computers they’re stored in. Systems that are vulnerable to model inversion—this is where attackers recover the training data through carefully constructed queries—are much more vulnerable to attacks that take advantage of unpatched vulnerabilities.

But while security is only as strong as the weakest link, this doesn’t mean we can ignore either cryptography or ML security. Here, our experience with cryptography can serve as a guide. Cryptographic attacks have different characteristics than software and network attacks, something largely shared with ML attacks. Cryptographic attacks can be passive. That is, attackers who can recover the plaintext from nothing other than the ciphertext can eavesdrop on the communications channel, collect all of the encrypted traffic, and decrypt it on their own systems at their own pace, perhaps in a giant server farm in Utah. This is bulk surveillance and can easily operate on this massive scale.

On the other hand, computer hacking has to be conducted one target computer at a time. Sure, you can develop tools that can be used again and again. But you still need the time and expertise to deploy those tools against your targets, and you have to do so individually. This means that any attacker has to prioritize. So while the NSA has the expertise necessary to hack into everyone’s computer, it doesn’t have the budget to do so. Most of us are simply too low on its priorities list to ever get hacked. And that’s the real point of strong cryptography: it forces attackers like the NSA to prioritize.

This analogy only goes so far. ML is not anywhere near as mathematically sound as cryptography. Right now, it is a sloppy misunderstood mess: hack after hack, kludge after kludge, built on top of each other with some data dependency thrown in. Directly attacking an ML system with a model inversion attack or a perturbation attack isn’t as passive as eavesdropping on an encrypted communications channel, but it’s using the ML system as intended, albeit for unintended purposes. It’s much safer than actively hacking the network and the computer that the ML system is running on. And while it doesn’t scale as well as cryptanalytic attacks can—and there likely will be a far greater variety of ML systems than encryption algorithms—it has the potential to scale better than one-at-a-time computer hacking does. So here again, good ML security denies attackers all of those attack vectors.

We’re still in the early days of studying ML security, and we don’t yet know the contours of ML security techniques. There are really smart people working on this and making impressive progress, and it’ll be years before we fully understand it. Attacks come easy, and defensive techniques are regularly broken soon after they’re made public. It was the same with cryptography in the 1990s, but eventually the science settled down as people better understood the interplay between attack and defense. So while Google, Amazon, Microsoft, and Tesla have all faced adversarial ML attacks on their production systems in the last three years, that’s not going to be the norm going forward.

All of this also means that our security for ML systems depends largely on the same conventional computer security techniques we’ve been using for decades. This includes writing vulnerability-free software, designing user interfaces that help resist social engineering, and building computer networks that aren’t full of holes. It’s the same risk-mitigation techniques that we’ve been living with for decades. That we’re still mediocre at it is cause for concern, with regard to both ML systems and computing in general.

I love cryptography and cryptanalysis. I love the elegance of the mathematics and the thrill of discovering a flaw—or even of reading and understanding a flaw that someone else discovered—in the mathematics. It feels like security in its purest form. Similarly, I am starting to love adversarial ML and ML security, and its tricks and techniques, for the same reasons.

I am not advocating that we stop developing new adversarial ML attacks. It teaches us about the systems being attacked and how they actually work. They are, in a sense, mechanisms for algorithmic understandability. Building secure ML systems is important research and something we in the security community should continue to do.

There is no such thing as a pure ML system. Every ML system is a hybrid of ML software and traditional software. And while ML systems bring new risks that we haven’t previously encountered, we need to recognize that the majority of attacks against these systems aren’t going to target the ML part. Security is only as strong as the weakest link. As bad as ML security is right now, it will improve as the science improves. And from then on, as in cryptography, the weakest link will be in the software surrounding the ML system.

This essay originally appeared in the May 2020 issue of IEEE Computer. I forgot to reprint it here.

Posted on February 6, 2023 at 6:02 AM • View Comments

Threats of Machine-Generated Text

With the release of ChatGPT, I’ve read many random articles about this or that threat from the technology. This paper is a good survey of the field: what the threats are, how we might detect machine-generated text, directions for future research. It’s a solid grounding amongst all of the hype.

Machine Generated Text: A Comprehensive Survey of Threat Models and Detection Methods

Abstract: Advances in natural language generation (NLG) have resulted in machine generated text that is increasingly difficult to distinguish from human authored text. Powerful open-source models are freely available, and user-friendly tools democratizing access to generative models are proliferating. The great potential of state-of-the-art NLG systems is tempered by the multitude of avenues for abuse. Detection of machine generated text is a key countermeasure for reducing abuse of NLG models, with significant technical challenges and numerous open problems. We provide a survey that includes both 1) an extensive analysis of threat models posed by contemporary NLG systems, and 2) the most complete review of machine generated text detection methods to date. This survey places machine generated text within its cybersecurity and social context, and provides strong guidance for future work addressing the most critical threat models, and ensuring detection systems themselves demonstrate trustworthiness through fairness, robustness, and accountability.

Posted on January 13, 2023 at 7:13 AM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.