=Paper= {{Paper |id=Vol-1649/187 |storemode=property |title=Vulnerability of Machine Learning Models to Adversarial Examples |pdfUrl=https://ceur-ws.org/Vol-1649/187.pdf |volume=Vol-1649 |authors=Petra Vidnerová, Roman Neruda |dblpUrl=https://dblp.org/rec/conf/itat/VidnerovaN16 }} ==Vulnerability of Machine Learning Models to Adversarial Examples== https://ceur-ws.org/Vol-1649/187.pdf
ITAT 2016 Proceedings, CEUR Workshop Proceedings Vol. 1649, pp. 187–194
http://ceur-ws.org/Vol-1649, Series ISSN 1613-0073, c 2016 P. Vidnerová, R. Neruda



                Vulnerability of machine learning models to adversarial examples

                                                     Petra Vidnerová, Roman Neruda

                                  Institute of Computer Science, Academy of Sciences of the Czech Republic
                                                             petra s. as. z

      Abstract: We propose a genetic algorithm for generating            We propose a genetic algorithm for generating adversarial
      adversarial examples for machine learning models. Such             examples. Though the evolution is slower than techniques
      approach is able to find adversarial examples without the          described in [12, 4], it enables us to obtain adversarial ex-
      access to model’s parameters. Different models are tested,         amples even without the access to model’s weights. The
      including both deep and shallow neural networks archi-             only thing we need is to be able to query the network to
      tectures. We show that RBF networks and SVMs with                  classify a given example. From this point of view, the mis-
      Gaussian kernels tend to be rather robust and not prone            classification of adversarial examples represent a security
      to misclassification of adversarial examples.                      flaw.
                                                                            This paper is organized as follows. Section 2 brings a
                                                                         brief overview of machine learning models considered in
      1   Introduction                                                   this paper. Section 3 describes the proposed genetic algo-
                                                                         rithm. Section 4 describes the results of our experiments.
      Deep networks and convolutional neural networks enjoy              Finally, Section 5 concludes our paper.
      high interest nowadays. They have become the state-of-
      art methods in many fields of machine learning, and have
      been applied to various problems, including image recog-           2     Deep and Shallow Architectures
      nition, speech recognition, and natural language process-
      ing [5].                                                           2.1   Deep and Convolutional Networks
         In [12] a counter-intuitive property of deep networks is
      described. It relates to the stability of a neural network         Deep neural networks are feedforward neural networks
      with respect to small perturbation of their inputs. The            with multiple hidden layers between the input and output
      paper shows that applying an imperceptible non-random              layer. The layers typically have different units depend-
      perturbation to an input image, it is possible to arbitrar-        ing on the task at hand. Among the units, there are tra-
      ily change the network prediction. These perturbations are         ditional perceptrons, where each unit (neuron) realizes a
      found by optimizing the input to maximize the prediction           nonlinear function, such as the sigmoid function: y(z) =
      error. Such perturbed examples are known as adversarial            tanh(z) or y(z) = 1+e1 −z . Another alternative to the percep-
      examples. On some datasets, such as ImageNet, the adver-           tron is the rectified linear unit (ReLU): y(z) = max(0, z).
      sarial examples were so close to the original examples that        Like the sigmoid neurons, rectified linear units can be used
      the differences were indistinguishable to the human eye.           to compute any function, and they can be trained using al-
         Paper [4] suggests that it is the linear behaviour in high-     gorithms such as back-propagation and stochastic gradient
      dimensional spaces what is sufficient to cause adversarial         descent.
      examples (for example, a linear classifier exhibits this be-          Convolutional layers contain the so called convolutional
      haviour too). They designed a fast method of generating            units that take advantage of the grid-like structure of the in-
      adversarial examples (adding small vector in the direction         puts, such as in the case of 2-D bitmap images, time series,
      of the sign of the derivation) and showed that adding these        etc. Convolutional units perform a simple discrete convo-
      examples to the training set further improves the general-         lution operation, which – for 2-D data – can be represented
      ization of the model. In [4], in addition, the authors state       by a matrix multiplication. Usually, to deal with large data
      that adversarial examples are relatively robust, and they          (such as large images), the convolution is applied multiple
      generalize between neural networks with varied number              times by sliding a small window over the data. The con-
      of layers, activations, or trained on different subsets of the     volutional units are typically used to extract some features
      training data. In other words, if we use one neural net-           from the data, and they are often used together with the so-
      work to generate a set of adversarial examples, these ex-          called max pooling layers that perform an input reduction
      amples are also misclassified by another neural network            by selecting one of many inputs, typically the one with
      even when it was trained with different hyperparameters,           maximal value. Thus, the overall architecture of a deep
      or when it was trained on a different set of examples. An-         network for image classification tasks resembles a pyra-
      other results of fooling deep and convolutional networks           mid with smaller number of units in higher layers of the
      can be found in [10].                                              networks.
         This paper examines a vulnerability to adversarial ex-             For the output layer, mainly for classification tasks, the
                                                                                                           zj
      amples throughout variety of machine learning methods.             softmax function: y(z) j = Ke ezk is often used. It has
                                                                                                       ∑k=1
188                                                                                                                  P. Vidnerová, R. Neruda

      the advantage that the output values can be interpreted as         some pixels. With the probability pmutate_pixel each pixel
      probabilities of individual classes.                               is changed:
         Networks with at least one convolutional layer are                                    ii = ii + r,
      called convolutional neural networks (CNN), while net-
                                                                         where r is drawn from Gaussian distribution. As a selec-
      works with all hidden layers consisting of perceptrons are
                                                                         tion, the tournament selection with tournament size 3 is
      called multi-layer perceptrons (MLP).
                                                                         used.
                                                                            The fitness function should reflect the following two cri-
      2.2   RBF networks and Kernel Methods                              teria:
      The history of radial basis function (RBF) networks can be             1. the individual should resemble the target image
      traced back to the 1980s, particularly to the study of inter-
      polation problems in numerical analysis [8]. The RBF net-              2. if we evaluate the individual by our machine learning
      work [3] is a feedforward network with one hidden layer                   model, we aim to obtain a prescribed target output
      realizing the basis functions and linear output layer. It rep-            (i.e., misclassify it).
      resents an alternative to classical models, such as multi-
      layer perceptrons. There is variety of learning methods for        Thus, in our case, a fitness function is defined
      RBF networks [9].                                                  as:    f (I) = −(0.5 ∗ cdist(I,target_image) + 0.5 ∗
         In 1990s, a family of machine learning algorithms,              cdist(model(I),target_answer)), where cdist is a
      known as kernel methods, became very popular. They                 Euclidean distance.
      have been applied to a number of real-world problems, and
      they are still considered to be state-of-the-art methods in        4     Experimental Results
      various domains [14].
         Based on theoretical results on kernel approximation,
                                                                         The goal of our experiments is to test various machine
      the popular support vector machine (SVM) [2, 13] algo-
                                                                         learning models and their vulnerability to adversarial ex-
      rithm was developed. Its architecture is similar to RBF –
                                                                         amples.
      one hidden layer of kernel units and a linear output layer.
      The learning algorithm is different, based on search for a
      separating hyperplane with the highest margin. Common              4.1    Overview of models
      kernel functions used for SVM learning are linear hx, x′ i,
      polynomial (γ hx, x′ i + r)d , Gaussian exp(−γ |x − x′ |2 ), and   As a representative of deep models we use two deep ar-
      sigmoid tanh(γ hx, x′ i + r).                                      chitectures – an MLP network with rectified linear units
         Recently, due to popularity of deep architectures, such         (ReLU), and a CNN. The MLP used in our experiments
      models with only one hidden layer are often referred to as         consist of three fully connected layers. Two hidden layers
      shallow models.                                                    have 512 ReLUs each, using dropout; the output layer has
                                                                         10 softmax units. The CNN has two convolutional lay-
                                                                         ers with 32 filters and ReLUs each, a max pooling layer,
      3     Genetic Algorithms                                           a fully connected layer of 128 ReLUs, and a fully con-
                                                                         nected output softmax layer. In addition to these two mod-
      To obtain an adversarial example for the trained machine           els, we also used an ensemble of 10 MLPs. All models
      learning model (such as a neural network), we need to              were trained using the KERAS library [1].
      optimize the input image with respect to network out-                 Shallow networks in our experiments are represented by
      put. For this task we employ genetic algorithms (GA).              an RBF network with 1000 Gaussian units, and SVM mod-
      GA represent a robust optimization method working with             els with Gaussian kernel (SVM-gauss), polynomial kernel
      the whole population of feasible solutions [7]. The popu-          of grade 2 and 4 (SVM-poly2 and SVM-poly4), sigmoidal
      lation evolves using operators of selection, mutation, and         kernel (SVM-sigmoid), and linear kernel (SVM-linear).
      crossover. Both the machine learning model and the target          SVMs were trained using the SCIKIT library [11], Grid
      output are fixed during the optimization.                          search and crossvalidation techniques were used to tune
         Each individual represents one possible input vector, i.e.      hyper-parameters. For RBF networks, we used our own
      one image encoded as a vector of pixel values:                     implementation. Overview of train and test accuracies can
                                                                         be found in Tab. 1.
                           I = {i1 , i2 , . . . , iN },

      where ii ∈< 0, 1 > are levels of grey, and N is the size of        4.2    Experimental setup
      a flatten image. (For the sake of simplicity, we consider
      only greyscale images in this paper, but it can be seen that       The well known MNIST data set [6] was used. It contains
      the same principle can be used for RGB images as well.)            70 000 images of hand written digits, 28 × 28 pixel each.
         The crossover operator performs a classical two-point           60 000 are used for training, 10 000 for testing. The ge-
      crossover. The mutation introduces a small change to               netic algorithm was run with 50 individuals, for 10 000
Vulnerability of Machine Learning Models to Adversarial Examples                                                                      189

                                                                         In general, it often happens that adversarial example




                  -li id
                        o
               M 2

               M 4



                       ar
                        s
                                                                       evolved for one model is misclassified by some of the other




             SV igm
             SV aus

             SV oly

             SV oly



                     ne
                  -g

                  -p

                  -p

                  -s
                                                                       models (see Tab. 6 and 7). There are some general trends:




               M

               M




               M
                N
              LP
                F


             CN
             RB




             SV
             M
                                                                           • adversarial example evolved for CNN was never mis-
      Train 0.96 1.00 1.00 0.99 1.00 0.99 0.87 0.95                          classified by other models, and CNN never misclas-
      Test 0.96 0.98 0.99 0.98 0.98 0.98 0.88 0.94                           sified other adversarial examples than those evolved
        Table 1: Overview of accuracies on train and test sets.              for the CNN;
                                                                           • adversarial examples evolved for MLP are misclas-
                                                                             sified also by ensemble of MLPs (all cases except
      generations, with crossover probability set to 0.6, and mu-
                                                                             two) and adversarial examples evolved for ensemble
      tation probability set to 0.1. The GA was run 9 times for
                                                                             of MLPs are misclassified by MLP (all cases);
      each model to find adversarial examples that resemble 9
      different images (training samples from the beginning of             • adversarial examples evolved for the SVM-sigmoid
      training set). All images were optimized to be classified              model are misclassified by SVM-linear (all cases ex-
      as zero.                                                               cept two);
                                                                           • adversarial examples for the SVM-poly2 model are
      4.3   Results                                                          often (6 cases) misclassified by other SVMs (SVM-
                                                                             poly4, SVM-sigmoid, SVM-linear), and in 4 cases
      Figures 1 and 2 show two selected cases from our set of                also by the SVM-gauss. In three cases it was also
      experiments. For example, the first set of images shows a              misclassified by MLP and ensemble of MLPs, in one
      particular image of digit five from the training set, and best         case, the adversarial example for SVM-poly2 is mis-
      evolved individuals from the corresponding runs of GA for              classified by all models but CNN (however, this ex-
      individual models.                                                     ample is quite noisy);
         In Tables 2–5, the outputs of individual models are
      listed. In Tab. 2 and 4, we show output vectors for train-           • adversarial example for the SVM-poly4 model is in
      ing sample of digit five and four, respectively. In Tab. 3             two cases misclassified by all models but CNN, in
      and 5, we show output vectors for adversarial examples                 different case it is misclassified by all but the CNN
      from Fig. 1 and 2, respectively.                                       and RBF models, and in one case by all but CNN,
                                                                             RBF, and SVM-gauss models;
         For this case, the adversarial examples were found for
      MLP, CNN, ensemble of MLPs, SVM-poly2, and SVM-                      • RBF network, SVM-gauss, and SVM-linear were re-
      sigmoid. For RBF network, SVM-gauss, SVM-poly4, and                    sistant to adversarial examples by genetic algorithm,
      SVM-linear, the GA was not able to find image that re-                 however they sometimes misclassify adversarial ex-
      sembles the digit 5 and at the same time it is classified as           amples of other models. These examples are already
      zero.                                                                  quite noisy, however by human they would still be
         If we look on a vulnerability of individual models over             classified correctly.
      all 9 GA runs we can conclude the following:

        • MLP, CNN, ensemble of MLPs, and SVM-sigmoid                  5    Conclusion
          were always misclassifying the best individuals;
                                                                       We proposed a genetic algorithm for generating adversar-
        • RBF network, SVM-gauss, and SVM-linear; never                ial examples for machine learning models. Our experi-
          misclassified, i.e. the genetic algorithm was not able       ment show that many machine models suffer from vulnera-
          to find adversarial example for these models;                bility to adversarial examples, i.e. examples designed to be
                                                                       misclassified. Some models are quite resistant to such be-
        • SVM-poly2 and SVM-poly4 were resistant to finding            haviour, namely models with local units – RBF networks
          adversarial examples in 2 and 5 cases, respectively.         and SVMs with Gaussian kernels. It seems that it is the lo-
                                                                       cal behaviour of units that prevents the models from being
         Fig. 3 and 4 deal with the generalization of adversar-        fooled.
      ial examples over different models. For each adversarial            Adversarial examples evolved for one model are often
      example the figure lists the output vectors of all models.       misclassified also by some of other models, as was elabo-
      In the case of a digit 3, the adversarial example evolved        rated in the experiments.
      for MLP is also misclassified by an ensemble of MLPs,
      and vice versa. Both examples are misclassified by SVM-
      sigmoid. However, adversarial example for the SVM-               Acknowledgements
      sigmoid is misclassified only by the SVM-linear model.           This work was partially supported by the Czech Grant
      Adversarial example for SVM-poly2 is misclassified also          Agency grant 15-18108S, and institutional support of the
      with other SVMs, except the SVM-gauss model.                     Institute of Computer Science RVO 67985807.
190                                                                                                               P. Vidnerová, R. Neruda




                                        0        1       2       3       4       5       6       7      8         9
                    RBF              0.04    -0.07    0.08    0.24   -0.04    0.73   -0.04    0.21   0.03     -0.18
                    MLP              0.00     0.00    0.00    0.00    0.00    1.00    0.00    0.00   0.00      0.00
                    CNN              0.00     0.00    0.00    0.00    0.00    1.00    0.00    0.00   0.00      0.00
                    ENS              0.00     0.00    0.00    0.00    0.00    1.00    0.00    0.00   0.00      0.00
                    SVM-gauss        0.00     0.00    0.00    0.00    0.00    1.00    0.00    0.00   0.00      0.00
                    SVM-poly2        0.00     0.00    0.00    0.02    0.00    0.98    0.00    0.00   0.00      0.00
                    SVM-poly4        0.00     0.00    0.00    0.02    0.00    0.98    0.00    0.00   0.00      0.00
                    SVM-sigmoid      0.01     0.00    0.03    0.32    0.00    0.61    0.00    0.01   0.01      0.01
                    SVM-linear       0.00     0.00    0.01    0.10    0.00    0.89    0.00    0.00   0.00      0.00

                            Table 2: Evaluation of the target digit five (see Fig. 1) by individual models.




                                        0        1       2       3       4       5       6       7      8         9
                    RBF              0.21    -0.05    0.09    0.23   -0.04    0.51   -0.05    0.17   0.07     -0.09
                    MLP              0.98     0.00    0.00    0.00    0.00    0.01    0.00    0.00   0.00      0.00
                    CNN              0.95     0.00    0.01    0.01    0.00    0.02    0.00    0.00   0.01      0.00
                    ENS              0.98     0.00    0.01    0.00    0.00    0.01    0.00    0.00   0.00      0.00
                    SVM-gauss        0.00     0.00    0.01    0.39    0.00    0.59    0.00    0.00   0.00      0.00
                    SVM-poly         0.88     0.00    0.02    0.02    0.00    0.07    0.00    0.00   0.00      0.00
                    SVM-poly4        0.01     0.01    0.14    0.29    0.01    0.50    0.01    0.01   0.02      0.01
                    SVM-sigmoid      0.82     0.00    0.03    0.05    0.00    0.08    0.00    0.01   0.01      0.01
                    SVM-linear       0.02     0.03    0.21    0.21    0.02    0.33    0.03    0.04   0.05      0.05

                          Table 3: Evaluation of adversarial digit five (from Fig. 1) by individual models.




                  Target                  RBF                   MLP                   CNN                     ENS




                 SVM-rbf             SVM-poly                SVM-poly4 SVM-sigmoid SVM-linear




      Figure 1: Best individuals evolved for individual models and digit five. The first ’Target’ image is the digit from the
      training set, than follows adversarial examples evolved for individual models.
Vulnerability of Machine Learning Models to Adversarial Examples                                                                191




                                             0       1       2        3      4      5       6     7        8        9
                      RBF                -0.06    0.07    0.16     0.06   0.67   0.00    0.01   0.15   -0.01    -0.05
                      MLP                 0.00    0.00    0.00     0.00   1.00   0.00    0.00   0.00    0.00     0.00
                      CNN                 0.00    0.00    0.00     0.00   1.00   0.00    0.00   0.00    0.00     0.00
                      ENS                 0.00    0.00    0.00     0.00   1.00   0.00    0.00   0.00    0.00     0.00
                      SVM-gauss           0.00    0.00    0.00     0.00   0.99   0.00    0.00   0.00    0.00     0.00
                      SVM-poly2           0.00    0.00    0.00     0.00   0.97   0.00    0.00   0.01    0.00     0.00
                      SVM-poly4           0.00    0.00    0.00     0.01   0.96   0.00    0.00   0.01    0.00     0.00
                      SVM-sigmoid         0.00    0.00    0.01     0.02   0.94   0.00    0.00   0.01    0.00     0.01
                      SVM-linear          0.00    0.01    0.05     0.04   0.84   0.00    0.01   0.04    0.00     0.02

                              Table 4: Evaluation of the target digit four (see Fig. 2) by individual models.




                                             0       1       2        3      4       5      6      7      8        9
                       RBF                0.06    0.08    0.14     0.08   0.49   -0.01   0.03   0.14   0.02     0.02
                       MLP                0.96    0.00    0.01     0.00   0.02    0.00   0.00   0.01   0.00     0.01
                       CNN                0.89    0.00    0.02     0.00   0.05    0.00   0.00   0.01   0.02     0.00
                       ENS                0.96    0.00    0.01     0.00   0.02    0.00   0.00   0.00   0.00     0.01
                       SVM-gauss          0.01    0.01    0.07     0.12   0.50    0.03   0.01   0.06   0.09     0.08
                       SVM-poly           0.75    0.00    0.03     0.01   0.09    0.00   0.01   0.04   0.03     0.04
                       SVM-poly4          0.71    0.01    0.04     0.01   0.11    0.02   0.02   0.04   0.02     0.02
                       SVM-sigmoid        0.84    0.00    0.02     0.03   0.03    0.02   0.01   0.01   0.00     0.03
                       SVM-linear         0.02    0.02    0.18     0.18   0.26    0.03   0.05   0.11   0.03     0.11

                            Table 5: Evaluation of adversarial digit four (from Fig. 2) by individual models.




                   Target                    RBF                    MLP                   CNN                   ENS




                  SVM-rbf               SVM-poly                 SVM-poly4 SVM-sigmoid SVM-linear




      Figure 2: Best individuals evolved for individual models and digit four. The first ’Target’ image is the digit from the
      training set, than follows adversarial examples evolved for individual models.
192                                                                                                           P. Vidnerová, R. Neruda




                   Evolved against RBF
      0
                                                               0    1    2    3    4    5      6     7   8     9
       5                                        RBF         0.16 0.06 0.12 0.79 0.01 -0.02 -0.06 -0.00 0.02 0.03
                                                MLP         0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00
      10                                        CNN         0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00
                                                ENS         0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00
      15                                        SVM-gauss 0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00
                                                SVM-poly    0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00
      20                                        SVM-poly4 0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00
                                                SVM-sigmoid 0.04 0.00 0.02 0.79 0.00 0.06 0.00 0.01 0.05 0.02
      25                                        SVM-linear 0.00 0.00 0.00 0.96 0.00 0.00 0.00 0.00 0.03 0.00
           0   5       10    15    20     25
                   Evolved against MLP
      0
                                                               0    1    2    3    4    5      6     7    8      9
       5                                        RBF         0.30 0.04 0.17 0.75 0.02 -0.03 -0.04 -0.01 -0.07 -0.00
                                                MLP         0.96 0.00 0.01 0.01 0.00 0.00 0.00 0.00 0.01 0.01
      10                                        CNN         0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00
                                                ENS         0.86 0.00 0.01 0.04 0.00 0.00 0.00 0.00 0.01 0.08
      15                                        SVM-gauss 0.00 0.00 0.00 0.99 0.00 0.00 0.00 0.00 0.00 0.01
                                                SVM-poly    0.04 0.00 0.01 0.91 0.00 0.00 0.00 0.00 0.02 0.02
      20                                        SVM-poly4 0.03 0.00 0.01 0.93 0.00 0.00 0.00 0.00 0.01 0.01
                                                SVM-sigmoid 0.49 0.00 0.03 0.30 0.00 0.04 0.00 0.01 0.10 0.02
      25                                        SVM-linear 0.25 0.02 0.10 0.30 0.02 0.05 0.02 0.03 0.18 0.06
           0   5       10    15    20     25

                   Evolved against CNN
      0
                                                               0    1    2    3    4    5      6    7    8    9
       5                                        RBF         0.12 0.05 0.15 0.89 0.01 -0.18 -0.02 0.02 0.10 -0.03
                                                MLP         0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00
      10                                        CNN         0.94 0.00 0.02 0.01 0.00 0.00 0.00 0.00 0.03 0.00
                                                ENS         0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00
      15                                        SVM-gauss 0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00
                                                SVM-poly    0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00
      20                                        SVM-poly4 0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00
                                                SVM-sigmoid 0.04 0.00 0.02 0.86 0.00 0.03 0.00 0.00 0.04 0.01
      25                                        SVM-linear 0.00 0.00 0.00 0.99 0.00 0.00 0.00 0.00 0.00 0.00
           0   5       10    15    20     25
                   Evolved against ENS
      0
                                                               0    1    2    3    4      5     6    7      8    9
       5                                        RBF         0.30 0.05 0.18 0.76 -0.01 -0.06 -0.04 -0.03 -0.05 -0.00
                                                MLP         0.83 0.00 0.05 0.06 0.00 0.00 0.00 0.00 0.05 0.00
      10                                        CNN         0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00
                                                ENS         0.96 0.00 0.01 0.02 0.00 0.00 0.00 0.00 0.01 0.00
      15                                        SVM-gauss 0.00 0.00 0.00 0.99 0.00 0.00 0.00 0.00 0.00 0.01
                                                SVM-poly    0.02 0.00 0.01 0.94 0.00 0.00 0.00 0.00 0.01 0.02
      20                                        SVM-poly4 0.01 0.00 0.00 0.96 0.00 0.00 0.00 0.00 0.01 0.01
                                                SVM-sigmoid 0.40 0.00 0.03 0.35 0.01 0.06 0.00 0.01 0.11 0.02
      25                                        SVM-linear 0.19 0.01 0.06 0.50 0.01 0.05 0.01 0.02 0.11 0.04
           0   5       10    15    20     25


                                         Figure 3: Model outputs for individual adversarial examples.
Vulnerability of Machine Learning Models to Adversarial Examples                                                       193




                 Evolved against SVM-RBF
        0
                                                                 0    1    2    3    4      5     6    7     8    9
        5                                         RBF         0.06 0.01 0.15 0.74 -0.00 -0.03 -0.04 -0.01 0.26 0.05
                                                  MLP         0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00
       10                                         CNN         0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00
                                                  ENS         0.00 0.00 0.00 0.99 0.00 0.00 0.00 0.00 0.01 0.00
       15                                         SVM-gauss 0.00 0.00 0.00 0.90 0.00 0.00 0.00 0.00 0.10 0.00
                                                  SVM-poly    0.00 0.00 0.00 0.50 0.00 0.00 0.00 0.00 0.50 0.00
       20                                         SVM-poly4 0.00 0.00 0.00 0.60 0.00 0.00 0.00 0.00 0.40 0.00
                                                  SVM-sigmoid 0.03 0.00 0.03 0.63 0.00 0.09 0.00 0.01 0.19 0.02
       25                                         SVM-linear 0.00 0.00 0.00 0.36 0.00 0.00 0.00 0.00 0.63 0.00
            0     5     10    15    20       25
                 Evolved against SVM-poly
        0
                                                                 0    1    2    3    4      5     6    7      8    9
        5                                         RBF         0.32 0.02 0.17 0.86 -0.01 -0.09 -0.09 -0.03 -0.12 0.01
                                                  MLP         0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00
       10                                         CNN         0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00
                                                  ENS         0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00
       15                                         SVM-gauss 0.00 0.00 0.00 0.99 0.00 0.00 0.00 0.00 0.00 0.00
                                                  SVM-poly    0.87 0.00 0.02 0.04 0.00 0.00 0.00 0.00 0.04 0.02
       20                                         SVM-poly4 0.38 0.01 0.11 0.23 0.01 0.02 0.01 0.02 0.15 0.04
                                                  SVM-sigmoid 0.55 0.01 0.04 0.19 0.01 0.05 0.01 0.01 0.13 0.02
       25                                         SVM-linear 0.71 0.01 0.02 0.06 0.01 0.02 0.01 0.01 0.15 0.01
            0     5     10    15    20       25

                 Evolved against SVM-poly4
        0
                                                                 0    1    2    3    4    5      6     7   8     9
        5                                         RBF         0.07 0.02 0.12 0.84 0.04 -0.07 -0.07 -0.01 0.10 0.06
                                                  MLP         0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00
       10                                         CNN         0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00
                                                  ENS         0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00
       15                                         SVM-gauss 0.00 0.00 0.00 0.99 0.00 0.00 0.00 0.00 0.01 0.00
                                                  SVM-poly    0.00 0.00 0.00 0.57 0.00 0.00 0.00 0.00 0.41 0.03
       20                                         SVM-poly4 0.00 0.00 0.00 0.67 0.00 0.00 0.00 0.00 0.31 0.03
                                                  SVM-sigmoid 0.04 0.00 0.02 0.73 0.01 0.07 0.00 0.01 0.08 0.02
       25                                         SVM-linear 0.01 0.00 0.00 0.58 0.00 0.00 0.00 0.00 0.39 0.01
            0     5     10    15    20       25

                Evolved against SVM-sigmoid
        0
                                                                 0    1    2    3    4      5     6    7    8      9
        5                                         RBF         0.30 0.04 0.22 0.94 -0.01 -0.14 -0.10 0.02 -0.21 -0.02
                                                  MLP         0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00
       10                                         CNN         0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00
                                                  ENS         0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00
       15                                         SVM-gauss 0.00 0.00 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00
                                                  SVM-poly    0.06 0.00 0.03 0.84 0.00 0.01 0.00 0.00 0.03 0.02
       20                                         SVM-poly4 0.04 0.00 0.01 0.93 0.00 0.00 0.00 0.00 0.01 0.01
                                                  SVM-sigmoid 0.74 0.00 0.02 0.12 0.00 0.02 0.00 0.00 0.08 0.01
       25                                         SVM-linear 0.41 0.02 0.06 0.18 0.02 0.05 0.02 0.03 0.17 0.05
            0     5     10    15    20       25


                                         Figure 4: Model outputs for individual adversarial examples.
194                                                                                                                 P. Vidnerová, R. Neruda

       Evolved for      Also misclassified by                          Evolved for        Also misclassified by
       Example 1:                                          digit 5     Example 8:                                    digit 3
       MLP              —                                              MLP                ensemble, SVM-sigmoid
       ensemble         MLP                                            ensemble           MLP, SVM-sigmoid
       CNN              —                                              CNN                —
       SVM-poly2        SVM-poly4, SMV-sigmoid,                        SVM-poly2          SVM-poly4, SVM-sigmoid, SVM-linear
                        SVM-linear                                     SVM-sigmoid        SVM-linear
       SVM-sigmoid      —                                              Example 9:                                    digit 1
       Example 3:                                  digit 4             MLP                ensemble
       MLP              ensemble                                       ensemble           MLP
       ensemble         MLP                                            CNN                —
       CNN              —                                              SVM-poly2          all except CNN
       SVM-poly2        ensemble, MLP, SVM-gauss, SVM-poly4,           SVM-sigmoid        MLP, ensemble, SVM-gauss,
                        SVM-sigmoid, SVM-linear                                           SVM-poly2, SVM-poly4, SVM-linear
       SVM-poly4        RBF, ensemble, MLP, SVM-gauss,         Example 10:                                           digit 4
                        SVM-poly4, SVM-sigmoid, SVM-linear     MLP                        ensemble
       SVM-sigmoid      SVM-linear                             ensemble                   MLP
       Example 4:                                  digit 1     CNN                        —
       MLP              ensemble                               SVM-poly2                  SVM-poly4, SVM-linear
       ensemble         MLP                                    SVM-poly4                  MLP, ensemble, SVM-gauss, SVM-poly2,
       CNN              —                                                                 SVM-sigmoid, SVM-linear
       SVM-poly2        SVM-gauss, SVM-poly4, SVM-sigmoid,     SVM-sigmoid                SVM-linear
                        SVM-linear
       SVM-sigmoid      SVM-linear                                Table 7: Generalization of adversarial examples.
       Example 5:                                  digit 9
       MLP              ensemble
                                                              [4] Ian J. Goodfellow, Jonathon Shlens, and Christian Szegedy.
       ensemble         MLP                                       Explaining and harnessing adversarial examples, 2014.
       CNN              —                                         arXiv:1412.6572.
       SVM-poly2        ensemble, MLP, SVM-poly2              [5] Yoshua Bengio Ian Goodfellow and Aaron Courville. Deep
                        SVM-poly4, SVM-sigmoid, SVM-linear        learning. Book in preparation for MIT Press, 2016.
       SVM-poly4        all except CNN                        [6] Yann LeCun and Corinna Cortes. The mnist database of
       SVM-sigmoid      SVM-linear                                handwritten digits, 2012.
       Example 6:                                  digit 2    [7] M. Mitchell. An Introduction to Genetic Algorithms. MIT
       MLP              —                                         Press, Cambridge, MA, 1996.
       ensemble         MLP                                   [8] J. Moody and C. Darken. Fast learning in networks
       CNN              —                                         of locally-tuned processing units. Neural Computation,
       SVM-poly4        MLP, ensemble, SVM-poly2,                 1:289–303, 1989.
                        SVM-sigmoid, SVM-linear               [9] R. Neruda and P. Kudová. Learning methods for radial ba-
       SVM-sigmoid      SVM-linear                                sis functions networks. Future Generation Computer Sys-
       Example 7:                                  digit 1        tems, 21:1131–1142, 2005.
       MLP              ensemble                             [10] Anh Mai Nguyen, Jason Yosinski, and Jeff Clune. Deep
       ensemble         MLP                                       neural networks are easily fooled: High confidence pre-
       CNN              —                                         dictions for unrecognizable images. CoRR, abs/1412.1897,
       SVM-sigmoid      —                                         2014.
                                                                      [11] F. Pedregosa et al. Scikit-learn: Machine learning in
         Table 6: Generalization of adversarial examples.                  Python. Journal of Machine Learning Research, 12:2825–
                                                                           2830, 2011.
                                                                      [12] Christian Szegedy, Wojciech Zaremba, Ilya Sutskever,
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