Evasion attacks against artificial intelligence (AI) are a type of attack where an attacker manipulates the input to an AI system in order to evade detection. This can be done by adding noise to the input, or by creating a new input that is similar to the original but with subtle differences.
Evasion attacks can be particularly challenging to detect because they often involve small changes to the input that are difficult to spot. For example, an attacker might add a single pixel of noise to an image in order to evade detection by an AI-powered image recognition system.
Evasion attacks can have serious consequences, including compromising the security of critical infrastructure and undermining trust in AI systems.
What are Adversarial Examples?
Adversarial examples are specially crafted inputs that undergo minuscule, algorithmically calculated perturbations, which can mislead machine learning models. These perturbations are trivial to a human observer but can have significant effects on a model's predictions.
Attacker's knowledge of the target system, or their "capability", is crucial in crafting adversarial examples. The more they know about the model and its architecture, the easier it is for them to mount an attack.
The three most powerful gradient-based attacks as of today are EAD (L1 norm), C&W (L2 norm), and Madry (Li norm). These attacks require access to the model's gradients and can be used to craft new adversarial examples to fool the model.
Adversarial examples are not just nuisances; they challenge the mathematical underpinnings of machine learning classifiers. They can be used to mislead models in various applications, including image classification.
The following are types of evasion attacks:
- Gradient-based attacks
- Confidence score attacks
- Hard label attacks
- Surrogate model attacks
- Brute-force attacks
The gradient-based maximum-confidence algorithm for generating evasion attacks is proposed in [biggio13-ecml] Biggio, B., Corona, I., Maiorca, D., Nelson, B., Šrndić, N., Laskov, P., Giacinto, G., Roli, F., 2013. Evasion Attacks against Machine Learning at Test Time. In ECML-PKDD 2013.
Why Adversarial Examples Exist
Adversarial examples exist due to various reasons, and there's no consensus in the community as to why they exist. A number of hypotheses exist.
One of the original hypotheses was proposed by Szegedy, where they argued that adversarial examples exist due to the presence of low-probability "pockets" in the manifold and poor regularization of networks.
Later, Goodfellow proposed a hypothesis arguing that adversarial examples occur due to too much linearity in modern machine learning and especially deep learning systems.
The third and perhaps most commonly adopted hypothesis today is the tilted boundary. In a nutshell, the authors argue that because the model never fits the data perfectly, there will always be adversarial pockets of inputs that exist between the boundary of the classifier and the actual sub-manifold of sampled data.
Research has shown that if the attacker has access to the model's gradients, they will always be able to craft a new set of adversarial examples to fool the model.
Here are some of the main hypotheses:
- Low-probability "pockets" in the manifold and poor regularization of networks
- Too much linearity in modern machine learning and especially deep learning systems
- Tilted boundary, where the model never fits the data perfectly and there are adversarial pockets of inputs that exist between the boundary of the classifier and the actual sub-manifold of sampled data
Crafting Adversarial Examples
Adversarial examples are specially crafted inputs that undergo minuscule perturbations to mislead machine learning models. They can be used to evade the intended operations of a model.
There are several types of adversarial attacks, including gradient-based, confidence score-based, hard label-based, surrogate model-based, and brute-force attacks. The most powerful gradient-based attacks are EAD (L1 norm), C&W (L2 norm), and Madry (Li norm).
To craft an adversarial example, you can use algorithms such as the gradient-based maximum-confidence algorithm, which is implemented in SecML by the CAttackEvasionPGDLS class. This algorithm uses a solver based on Projected Gradient Descent with Bisect Line Search, implemented by the COptimizerPGDLS class.
Here are the key attack parameters to consider:
By carefully selecting these parameters, you can create an effective adversarial example that evades the model's intended operations.
Definition
Adversarial examples are not just minor annoyances, but rather a serious challenge to the mathematical foundations of machine learning classifiers.
These specially crafted inputs undergo minuscule, algorithmically calculated perturbations that can mislead machine learning models. Techniques like the Fast Gradient Sign Method (FGSM) or Carlini & Wagner (C&W) attacks can be used to generate these adversarial instances by adjusting input features based on the gradient of the loss function relative to the input data.
Model Evasion refers to the tactical manipulation of input data, algorithmic processes, or outputs to mislead or subvert the intended operations of a machine learning model.
In mathematical terms, evasion can be considered an optimization problem, where the objective is to minimize or maximize a certain loss function without altering the essential characteristics of the input data.
Modifying the input data x such that f(x) does not equal the true label y, where f is the classifier and x is the input vector, is a key aspect of Model Evasion.
The goal of Model Evasion is to deceive the machine learning model into producing an incorrect output, without changing the fundamental characteristics of the input data.
Crafting Adversarial Examples
Adversarial examples are specially crafted inputs that undergo minuscule, algorithmically calculated perturbations, which can mislead machine learning models. These perturbations are trivial to a human observer but sufficient to cause a machine learning model to misclassify.
There are different types of adversarial attacks, including gradient-based attacks, confidence score attacks, hard label attacks, surrogate model attacks, and brute-force attacks. Gradient-based attacks are the most powerful and require access to the model's gradients, making them a type of WhiteBox attack.
The three most powerful gradient-based attacks are EAD (L1 norm), C&W (L2 norm), and Madry (Li norm). These attacks use the model's gradients to mathematically optimize the attack and can be used to craft new sets of adversarial examples to fool the model.
Confidence score attacks, on the other hand, use the outputted classification confidence to estimate the gradients of the model and then perform similar smart optimization. This approach doesn't require the attacker to know anything about the model and hence is of the BlackBox type.
Here are the three most powerful confidence-based attacks:
- ZOO
- SPSA
- NES
To craft adversarial examples, we can use algorithms like the gradient-based maximum-confidence algorithm, which is implemented in SecML by the CAttackEvasionPGDLS class. This algorithm uses a solver based on Projected Gradient Descent with Bisect Line Search to generate the adversarial examples.
The attack parameters can be specified while creating the attack, and must be optimized depending on the specific optimization problem. For example, we can choose to generate an l2 perturbation within a maximum ball of radius eps=0.4 from the initial point.
The classifier has been successfully evaded in both cases, and the PGD-LS solver with bisect line search queries the classifier gradient function many times less, thus generating the adversarial examples much faster.
The adversarial examples can be visualized on a 2D plane, showing the value of the objective function of the attacks. The initial point x0 (red hexagon) has been perturbed in the feature space so that it is actually classified by the SVM as a point from another class.
Evading AI Techniques
Evasion attacks are a serious threat to AI systems, and understanding the techniques used to evade them is crucial for their security. Adversarial examples, which are carefully crafted inputs that look normal to humans but are designed to fool AI models, are a key component of evasion attacks.
There are several types of evasion attacks, including simple evasion, adversarial attacks, and data poisoning. Simple evasion tactics, such as manipulating observable features in input data, can be effective against weak or poorly-trained machine learning models. Adversarial attacks, on the other hand, exploit the mathematical properties of machine learning models to create perturbed versions of input data that lead to misclassification.
The Fast Gradient Sign Method (FGSM) and Jacobian-based Saliency Map Attack (JSMA) are two common techniques used in adversarial attacks. FGSM uses the gradients of the loss function to create a perturbed version of the input, while JSMA takes a more targeted approach by iteratively perturbing features that are most influential for a given classification.
Evading AI Techniques: A Breakdown
Data poisoning attacks, which involve tampering with training data to embed vulnerabilities into the model, are another type of evasion attack. This can be done in a surreptitious manner, making it difficult to detect during the training process.
Model manipulation, which involves gaining unauthorized access to internal parameters of the model and recalibrating its decision boundaries, is also a type of evasion attack. This can be done by directly manipulating weights and biases in a neural network, for example.
Types of Attacks
Adversarial attacks are a sophisticated class of evasion tactics that exploit the mathematical properties of machine learning models. They can be generated through various optimization techniques aimed at altering the model's output classification.
The three most powerful gradient-based attacks as of today are EAD (L1 norm), C&W (L2 norm), and Madry (Li norm). These attacks use the model's gradients to mathematically optimize the attack.
Confidence score attacks use the outputted classification confidence to estimate the gradients of the model, and then perform similar smart optimization to gradient-based attacks. The three most powerful confidence-based attacks as of today are ZOO, SPSA, and NES.
Simple evasion tactics generally rely on manipulating observable features in input data to circumvent detection by weak or poorly-trained machine learning models. For example, altering the hash of a malicious file could effectively prevent its identification by simple hash-based classifiers.
Types of evasion attacks include simple evasion, adversarial attacks, and brute-force attacks. The most powerful gradient-based attacks are EAD, C&W, and Madry, while the most powerful confidence-based attacks are ZOO, SPSA, and NES.
Adversarial attacks can be categorized into five separate classes: those that use gradients, those that use confidence scores, those that use hard labels, those that use surrogate models, and brute-force attacks.
Data Poisoning
Data poisoning attacks are a sneaky way attackers manipulate machine learning models. They tamper with the training data to embed vulnerabilities into the model itself.
An attacker might introduce anomalous traffic patterns as normal behavior in the training dataset, diluting the model's understanding of what constitutes an 'attack'. This reduces the model's efficacy in a live environment.
Data poisoning attacks are often done in a surreptitious manner, so the poisoned data doesn't raise flags during the training process. This makes it harder to detect and prevent these types of attacks.
In a supervised learning scenario for network intrusion detection, an attacker might intentionally add anomalous data to the training dataset. This can cause the model to misclassify attacks as normal behavior, making it less effective in detecting actual threats.
Data poisoning attacks can have serious consequences, including reduced True Positive Rate (TPR) and increased False Negative Rate (FNR) of the classifier. This can lead to undetected attacks and compromised system integrity.
Evading AI Techniques
Evading AI Techniques is a rapidly evolving field, and understanding its ins and outs is crucial for anyone looking to outsmart AI systems.
Adversarial attacks are a type of evasion attack that can be used to manipulate machine learning models. These attacks can be simple or sophisticated, depending on the attacker's goals and capabilities.
Simple evasion tactics often rely on manipulating observable features in input data to circumvent detection by weak or poorly-trained machine learning models. For example, altering the hash of a malicious file could effectively prevent its identification by simple hash-based classifiers.
Adversarial examples can be generated through various optimization techniques aimed at altering the model's output classification. Fast Gradient Sign Method (FGSM) is a technique that uses the gradients of the loss function with respect to the input data to create a perturbed version of the input that leads to misclassification.
There are five separate classes of evasion attacks, including those that use gradients, confidence scores, hard labels, surrogate models, and brute-force attacks. Gradient-based attacks are particularly powerful, as they require access to the model's gradients and can be used to mathematically optimize the attack.
Here are some of the most powerful gradient-based attacks as of today:
- EAD (L1 norm)
- C&W (L2 norm)
- Madry (Li norm)
Confidence score attacks use the outputted classification confidence to estimate the gradients of the model, and then perform similar smart optimization to gradient-based attacks. This approach doesn't require the attacker to know anything about the model and hence is of the BlackBox type.
Data poisoning attacks represent a more insidious form of manipulation. Instead of targeting the model during inference, the attacker tampers with the training data to embed vulnerabilities into the model itself. This is often done in a surreptitious manner so that the poisoned data doesn’t raise flags during the training process but manifests its effects when the model is deployed.
Model manipulation is an overt assault on the machine learning model’s architectural integrity. Here, the attacker gains unauthorized access to the internal parameters of the model, such as the weights and biases in a neural network, to recalibrate its decision boundaries. By directly manipulating these parameters, the attacker can induce arbitrary and often malicious behavior.
Conclusions
Addressing model evasion tactics is a critical challenge in AI and cybersecurity, essential for maintaining the integrity and reliability of AI systems.
Defending against evasion is not a mere technical obstacle, but a complex, evolving discipline that requires a multi-dimensional approach.
The significant impact of evasion on AI models makes it crucial for researchers, practitioners, and policymakers to focus on this issue.
Elevating evasion as a practical and regulatory priority requires immediate and sustained action to mitigate its effects on AI systems.
Defending Against Adversarial Examples
Adversarial examples are not just a nuisance, they can actually trick machine learning models into misclassifying objects. These specially crafted inputs undergo minuscule, algorithmically calculated perturbations that are trivial to a human observer but sufficient to fool models.
To defend against these adversarial examples, techniques like the Fast Gradient Sign Method (FGSM) or Carlini & Wagner (C&W) attacks can be used to generate them. These attacks iteratively adjust input features based on the gradient of the loss function relative to the input data.
Defending against adversarial examples requires a deep understanding of how they're generated. By studying the methods used to create them, such as the FGSM or C&W attacks, we can develop strategies to mitigate their impact.
Defending Against Adversarial Examples
Adversarial examples can be generated using techniques like the Fast Gradient Sign Method (FGSM) or Carlini & Wagner (C&W) attacks, which iteratively adjust input features based on the gradient of the loss function relative to the input data.
These attacks can mislead machine learning models, such as convolutional neural networks trained for image classification, into classifying benign objects as threatening ones.
To defend against these examples, researchers are exploring techniques like adversarial training, which involves training models on adversarial examples generated by FGSM or C&W attacks.
Adversarial training can improve a model's robustness to adversarial examples, but it's not a foolproof solution.
The goal of adversarial training is to make the model more resilient to the subtle perturbations that can lead to misclassification.
By training on a diverse set of adversarial examples, researchers can create models that are less susceptible to these types of attacks.
However, the effectiveness of adversarial training depends on the specific attack method used to generate the adversarial examples.
Researchers are also exploring other techniques, such as input validation and data preprocessing, to defend against adversarial examples.
These techniques can help to detect and reject adversarial examples before they reach the model.
However, the development of more sophisticated attack methods may require the development of more robust defense techniques.
Regular Updates and Monitoring
Regular updates and monitoring are crucial in defending against adversarial examples. Machine learning models in cybersecurity should undergo frequent updates to stay ahead of new threats.
Adaptive learning algorithms can incrementally update the model in the face of new data, making them invaluable in this context. This allows the model to learn from new information and improve its performance over time.
Monitoring should include not only performance metrics but also anomaly detection systems that can flag unusual model behavior indicative of an attack. Automated version control systems can roll back models to a previous state in case of a detected manipulation.
Real-time alerting mechanisms can notify human overseers of potential issues, enabling swift action to be taken. This proactive approach can help prevent attacks from succeeding and minimize the damage caused by adversarial examples.
Sources
- https://towardsdatascience.com/evasion-attacks-on-machine-learning-or-adversarial-examples-12f2283e06a1
- https://www.nist.gov/news-events/news/2024/01/nist-identifies-types-cyberattacks-manipulate-behavior-ai-systems
- https://medium.com/nfactor-technologies/part-1-navigating-the-threat-of-evasion-attacks-in-ai-4d7ea9831143
- https://secml.readthedocs.io/en/stable/tutorials/03-Evasion.html
- https://securing.ai/ai-security/ai-model-evasion/
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