miércoles, 31 de mayo de 2023

5 Free Online Courses To Learn Artificial Intelligence

We are living in the era of fourth industrial revolution(4IR), where Artificial intelligence has a significant role to play. This 4IR technology embedded within societies and even into the human body. From Computer enthusiasts to common people, everyone should be aware and learn this breakthrough technology.
We think about gigantic Robots from Transformers when we hear about Artificial Intelligence(AI) which is a fiction in the past but a fact today, capable of transforming the whole tech world. The field of AI consists of more than Robots such as personal assistants, self-driving cars, apprenticeship learning, behavior cloning and so on. To learn about this advanced technology, thanks to the online learning resources which offers great content to get started with artificial intelligence.

Here are the 5 free e-learning courses on Artificial Intelligence

1. UC Berkeley CS188 Intro to AI

Get started with UC Berkeley AI course, this course is absolutely for beginners who are unaware of Artificial intelligence. It doesn't need any prior computer knowledge to know about AI. UC Berkeley allows anyone to learn this course for free. This course is systematically presented and consists of the following:
  • Course Schedule
  • Complete sets of Lecture Slides and Videos
  • Interface for Electronic Homework Assignments
  • Section Handouts
  • Specs for the Pacman Projects
  • Source files and PDFs of past Berkeley CS188 exams
  • Form to apply for edX hosted autograders for homework and projects (and more)
  • Contact information
Aside from this, you can also browse the following courses as well from UC Berkeley that are part of AI course:
  • Machine Learning: CS189, Stat154
  • Intro to Data Science: CS194-16
  • Probability: EE126, Stat134
  • Optimization: EE127
  • Cognitive Modeling: CogSci131
  • Machine Learning Theory: CS281A, CS281B
  • Vision: CS280
  • Robotics: CS287
  • Natural Language Processing: CS288

2. Artificial Intelligence: Principles and Techniques

This course is offered by Stanford with great content that includes topics, videos, assignments, projects, and exams. The whole course mainly focuses on the complex real-world problems and try to find similarity between web search, speech recognition, face recognition, machine translation, autonomous driving, and automatic scheduling. Here you will learn the foundational principles of AI and implement some the AI systems. The goal of this course is to help you tackle the real-world situations with the help of AI tools. So, it is the best for the beginner to get started with AI.

3. Learn with GOOGLE AI

Who will dislike the course from Google? absolutely no one. This company is one of the early adopters of AI has a lot to offer to learners. Learn with Google AI is an education platform for people at all experience levels, it is free to access and browse content. The education resources provided by Google is from the machine learning experts of the company. These resources are the collections of lessons, tutorials, and Hands-on exercises that help you start learning, building, and problem-solving.

4. MIT 6.S094: Deep Learning for Self-Driving Cars

This course gives the practical overview of Deep Learning and AI. It is the course for beginners, also for the people who are getting started with Machine Learning. The course also offers a lot of benefits to the experienced and advanced researchers in the field deep learning. This MIT's course takes people into the journey of Deep Learning with the applied theme of building Self-Driving cars. However, the course also offers slides and videos to engage the learners.

5. Fundamentals of Deep Learning for Computer Vision

This course is offered by Nvidia and Nvidia Deep learning Institute. Computer Vision is one of the disciplines of AI that acquire, analyze, process, and understand images. The course is completely free and everyone who is enthusiast about AI can access and learn the course. It is a hands-on course that able to provide basics of deep learning and deployment of neural networks. With this. you will also learn the following:
  • Identify the ingredients required to start a Deep Learning project.
  • Train a deep neural network to correctly classify images it has never seen before.
  • Deploy deep neural networks into applications.
  • Identify techniques for improving the performance of deep learning applications.
  • Assess the types of problems that are candidates for deep learning.
  • Modify neural networks to change their behavior.

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Probing For XML Encryption Weaknesses In SAML With EsPReSSO

Security Assertion Markup Language (SAML) is an XML-based standard commonly used in Web Single Sign-On (SSO) [1]. In SAML, the confidentiality of transferred authentication statements against intermediaries can be provided using XML Encryption [2]. However, implementing XML Encryption in a secure way can be tricky and several attacks on XML Encryption have been identified in the past [3] [4]. Therefore, when auditing a SAML endpoint, one should always consider testing for vulnerabilities in the XML Encryption implementation.

This blog post introduces our latest addition to the SAML Attacker of our BurpSuite extension EsPReSSO: the Encryption Attack tab. The new tab allows for easy manipulation of the encrypted parts within intercepted SAML responses and can, therefore, be used to quickly assess whether the SAML endpoint is vulnerable against certain XML Encryption attacks.


Weaknesses of XML Encryption

Implementations of XML Encryption can be vulnerable to adaptive chosen ciphertext attacks. This is a class of attacks in which the attacker sends a sequence of manipulated ciphertexts to a decryption oracle as a way to gain information about the plaintext content.
Falsely implemented XML Encryption can be broken using:
  • an attack against the CBC-mode decryption (quite similar to a padding oracle attack) [3] or
  • a Bleichenbacher attack against the RSA-PKCS#1 encryption of the session key  [4].
SAML makes use of XML Encryption and its implementations could, therefore, also be vulnerable to these attacks.

XML Encryption in SAML

To support confidential transmission of sensitive data within the SAML Assertion, assertions can be encrypted using XML Encryption. An EncryptedAssertion is shown in the abridged example below.

<EncryptedAssertion>
  <EncryptedData>
    <EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#aes128-cbc"/>
    <KeyInfo>
      <EncryptedKey>
        <EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#rsa-1_5"/>
        <CipherData>
          <CipherValue>
            [...]
          </CipherValue>
        </CipherData>
      </EncryptedKey>
    </KeyInfo>
    <CipherData>
        <CipherValue>
          [...]
        </CipherValue>
    </CipherData>
  </EncryptedData>
</EncryptedAssertion>

The EncryptedAssertion contains an EncryptedData element, which in turn is the parent of the EncryptionMethod, KeyInfo, and CipherData elements.  SAML makes use of what is referred to as a hybrid encryption scheme. This is done using a session key which symmetrically encrypts the payload data (the example uses AES-128 in CBC mode), resulting in the ciphertext contained in the EncryptedAssertion/EncryptedData/CipherData/CipherValue child element. The session key itself is encrypted using an asymmetric encryption scheme. In our example, RSA-PKCS#1.5 encryption is used with the public key of the recipient, allowing the contents of the the EncryptedKey child element to be derived from the KeyInfo element. 

Encryption Attacker

Our BurpSuite extension EsPReSSO can help detect vulnerable implementations with the newly integrated Encryption Attacker within EsPReSSO's SAML module.

Once a SAML response which contains an EncryptedAssertion has been intercepted, open the SAML tab, select the Attacks pane, and choose Encryption from the dropdown menu. This works in Burp's Proxy, as well as in the Repeater tool, and is depicted below.
As sketched out above, the symmetric session key is encrypted using the recipient's public key. Since the key is public, anybody can use it to encrypt a selected symmetric key and submit a valid encryption of arbitrary messages to the recipient. This is incredibly helpful because it allows us to produce ciphertexts that decrypt the chosen plaintexts. To accomplish this, one can purposefully send invalidly padded messages, or messages containing invalid XML, as a method to trigger and analyze the different reactions of the decryption endpoint (i.e, turning the endpoint into a decryption oracle). To facilitate these investigations, the new Encryption Attacker makes this process dead simple.
The screenshot above shows the essential interface of the new encryption tab:
At the top, the certificate used to encrypt the symmetric session key can be pasted into the text field. This field will be pre-filled automatically if the intercepted SAML message includes a certificate in the KeyInfo child element of the EncryptedData element. The Update Certificate checkboxes above the text area can be used to include the certificate in the manipulated SAML message.
In the Symmetric Key text field, the hexadecimal value of the symmetric session key can be set. Choose the asymmetric algorithm from the dropdown menu and click Encrypt key -- this will update the corresponding KeyInfo elements of the intercepted SAML message. 

The payload in the text area labeled XML data can now be entered. Any update in the XML data field will also be reflected in the hexadecimal representation of the payload (found on right of the XML data field). Note that this is automatically padded to the blocklength required by the symmetric algorithm selected below. However, the payload and the padding can be manually adjusted in the hex editor field.

Eventually, click the Encrypt content button to generate the encrypted payload. This will apply the changes to the intercepted SAML message, and the manipulated message using Burp's Forward or Go button can now be forwarded, as usual.

Probing for Bleichenbacher Oracles

Bleichenbacher's attack against RSA-PKCS1 v1.5 encryption abuses the malleability of RSA to draw conclusions about the plaintext by multiplying the ciphertext with adaptively chosen values, and observing differences in the received responses. If the (error-) responses differ for valid and invalid PKCS1 v1.5 ciphertexts, Bleichenbachers' algorithm can be used to decrypt the ciphertext without knowing the private key [6].

To determine whether or not a SAML endpoint is vulnerable to Bleichenbacher's Attack, we simply need to check if we can distinguish those responses received when submitting ciphertexts that are decrypted into invalidly formatted PKCS1 v1.5 plaintexts, from the responses we receive when sending ciphertexts that are decrypted into validly formatted plaintexts. 

Recall that PKCS1 v1.5 mandates a certain format of the encrypted plaintext, namely a concatenation of a BlockType 00 02, a randomized PaddingString (PS) that includes no 00 bytes, a 00 (NULL-byte) as delimiter, and the actual plaintext message. The whole sequence should be equal in size to the modulus of the RSA key used. That is, given the byte length k of the RSA modulus and the message length |m|, PS has the length |PS| = k - 3 - |m|. Furthermore, PKCS1 v1.5 demands that |PS| to be at least eight bytes long [5]. 

In SAML, the recipient's public key is usually known because it is published in the metadata, or even included in the EncryptedAssertion. For this reason, we do not need to fiddle around with manipulated ciphertexts. Instead, we simply submit a validly formatted RSA-PKCS1 v1.5 encrypted message and an encrypted message which deciphers into an invalidly formatted plaintext. As an example, assume an RSA public key of 2048 bits which we want to use to encrypt a 16 byte session key `01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F 10` (hexadecimal representation). |PS|$ is $2048/8 - 3 - 16 = 237, so a valid PKCS1 v1.5 plaintext, ready to be encrypted using `AA` for all 237 padding bytes, could look like the listing shown below.

00 02 AA AA AA AA AA AA AA AA AA AA AA AA AA AA
AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA
AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA
AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA
AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA
AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA
AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA
AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA
AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA
AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA
AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA
AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA
AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA
AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA
AA AA AA AA AA AA AA AA AA AA AA AA AA AA AA 00
01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F 10
In the Encryption attack pane of EsPReSSO, ensure that the correct public key certificate has been added to the Certificate field. Insert a valid plaintext, such as the one above, into the Symmetric Key field and select Plain RSA encryption from the Algorithm drop down menu. Click the Encrypt button to compute the RSA transformation and apply the new EncryptedKey element to the intercepted SAML message. Now, submit the message by clicking Burp's Go or Forward button and carefully inspect the response.

Next, repeat the steps outlined above, but this time submit an invalid PKCS1 v1.5 message. For example, consider using an invalid BlockType of `12 34` instead of `00 02`, or replace the `00` delimiter so that the decryptor is unable to determine the actual message after decrypting the ciphertext. If you are able to determine from the recieved responses whether or not the submitted ciphertext decrypted into a valid PKCS1 v1.5 formatted plaintext, chances are high that the decryptor can be used as a Bleichenbacher oracle. Don't forget to take into account the actual XML data, i.e., the assertion encrypted with the new session key; by submitting valid or invalid XML, or by removing signatures from the SAML message or the assertion you may increase your chances of detecting differences in the returned responses.

Probing for Oracles in CBC-Mode Decryption

Another known attack on XML Encryption is aimed at the Cipher Block Chaining (CBC) mode, which can be used with the block ciphers AES or 3DES [2]. The attack is described in detail in this referenced paper [3] and is quite similar to Padding-Oracle attacks on CBC mode; the malleability of CBC mode encryption enables the attacker to perform a bytewise, adaptive manipulation of the ciphertext blocks which are subsequently sent to the decryptor. In most cases, the manipulated ciphertext will not decrypt to valid XML and an error will be returned. Sometimes, however, the plaintext will be parsed as valid XML, in which cases an error is thrown later on at the application layer. The attacker observes the differences in the responses in order to turn the decryptor into a ciphertext validity oracle which can be used to break the encryption.  Due to some particularities of the XML format, this attack can be very efficient, enabling decryption with about 14 requests per byte, and it is even possible to fully automate the process [7].

In order to determine if a particular SAML service provider is vulnerable to this attack, we can avoid the cumbersome ciphertext manipulation, if we are in possession of the decryptor's public key:
In the Encryption Attacker tab of EsPReSSO, add the public key certificate to the Certificate field (if necessary) and insert a symmetric key of your own devising into the  Symmetric Key text field. Select an appropriate RSA encryption method and click the Encrypt button to apply the new EncryptedKey element to the original SAML message. 

An XML message can now be inserted into the XML data text field. Select a CBC mode encryption algorithm and click Encrypt to apply the changes. As in the example above, press Burp's Go or Forward button to send the message and carefully inspect the response. Try sending invalid XML, e.g., by not closing a tag or using the `&` character without a valid entity and keep an eye open for differences in the returned responses. To manipulate the padding, the text field on the right side shows the hexadecimal representation of the plaintext, including the CBC padding. If you send a single block and set the last byte, which indicates the padding length to the blocksize, i.e. 16 or 0x10 for AES, the ciphertext should decrypt into an empty string and is generally considered "valid" XML.

Please refer to the original paper for more details, tips, and tricks for performing the actual attack [3]. 

Summary

The new XML Encryption attacker included in EsPReSSO can help security auditors to quickly assess if a SAML endpoint is vulnerable to known attacks against XML Encryption. To this end, the decryptor's public key is used in order to send suitable test vectors that can be provided in plaintext. Ciphertext manipulation is, therefore, not required. The actual process of decrypting an intercepted SAML message is, however, considered out of scope and not implemented in EsPReSSO.

In case you wonder how XML Encryption can be used in a secure fashion, here are some considerations [6]:
  • Always use an authenticated encryption mode such as AES-GCM instead of the CBC-mode encryption.
  • Using RSA-PKCS1 v1.5 within XML Encryption is particularly difficult to do in a secure manner, and it is recommended to use RSA with Optimal Asymmetric Encryption Padding (OAEP) instead [2].
  • Apply a digital signature over the whole SAML response, and ensure it is properly validated before attempting to decrypt the assertion. This should thwart the attack as a manipulated response can be recognized as such and should be rejected.
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Hacking All The Cars - Part 2


Connecting Hardware to Your Real Car: 

 I realized the other day I posted Part 2 of this series to my youtube awhile ago but not blogger so this one will be quick and mostly via video walkthrough. I often post random followup videos which may never arrive on this blog. So if you're waiting on something specific I mentioned or the next part to a series its always a good idea to subscribe to the YouTube. This is almost always true if there is video associated with the post.  

In the last blog we went over using virtual CAN devices to interact with a virtual car simulators of a CAN network This was awesome because it allowed us to learn how to interact with he underlying CAN network without fear of hacking around on an expensive automobile. But now it's time to put on your big boy pants and create a real CAN interface with hardware and plug your hardware device into your ODB2 port. 

The video I created below will show you where to plug your device in, how to configure it and how to take the information you learned while hacking around on the virtual car from part1 and apply it directly to a real car.   

Video Walk Through Using Hardware on a Real Car




As a reference here are the two device options I used in the video and the needed cable: 

Hardware Used: 

Get OBD2 Cable:
https://amzn.to/2QSmtyL

Get CANtact:
https://amzn.to/2xCqhMt

Get USB2CAN:
https://shop.8devices.com/usb2can


Creating Network Interfaces: 

As a reference here are the commands from the video for creating a CAN network interface: 

USB2Can Setup: 
The following command will bring up your can interface and you should see the device light color change: 
sudo ip link set can0 up type can bitrate 125000

Contact Setup: 
Set your jumpers on 3,5 and 7 as seen in the picture in the video
Sudo slcand -o -s6 /dev/ttyACM can0 <— whatever device you see in your DMESG output
Ifconfig can0 up

Summary: 

That should get you started connecting to physical cars and hacking around. I was also doing a bit of python coding over these interfaces to perform actions and sniff traffic. I might post that if anyone is interested. Mostly I have been hacking around on blockchain stuff and creating full course content recently so keep a look out for that in the future. 

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