• Top 10 JavaScript Hack for Optimized Performance

    JavaScript has been ruling the tech arena for more than two decades and helping developers simplifying complex tasks. It allows developers to implement complex task web pages in a most simplified manner. For most of the developers minified JavaScript file is the common phenomena while very few developers may be aware of Optimized JavaScript code. While meeting through many Javascript developers, I have come to know that Optimized JavaScript code is something that confuses developers, some of them might be doing it, but they are not aware of this.

    What is an Optimized JavaScript Code

    When combinations of uniquely programmed logics along with small hacks utilized to enhance performance and speed is known as Optimized JavaScript code. Optimization not only optimizes performance and speed but also saves maximum development time. When you save time, you save some bucks as well.

    So, I am here with some useful and fruitful hacks to help developers optimize performance, enhance speed and save time. Hope, you like the article and after going through it, you may utilize the best of Optimized JavaScript code.

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  • Protocol for communication between iframe and the main window

    • Translation

    From time to time, developers need to establish communication between several browser tabs to be able to send messages from one tab to another and receive responses. We have also faced this need at some point.

    Some solutions already exist (like, for instance, BroadcastChannel API). However, its browser support leaves a lot to be desired, so we decided to use our own library. When the library was ready, that functionality was no longer required. Nevertheless, another task emerged: communication between an iframe and the main window.

    On closer examination, it turned out that two-thirds of the library would not have to be changed — only some code refactoring was necessary. The library is a communication PROTOCOL that can work with text data. It can be applied in all cases in which text is transferred, such as iframes, window.open, worker, browser tabs or WebSocket.

    How it works

    Currently, the protocol has two functions: sending messages and subscription to events. Any message in the protocol is a data object. For us, the main field in that object is type, which tells us what kind of message it is. The type field is an enum with the following values:

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  • Let's help QueryProvider deal with interpolated strings

    • Translation

    Specifics of QueryProvider

    QueryProvider can’t deal with this:

    var result = _context.Humans
                          .Select(x => $"Name: {x.Name}  Age: {x.Age}")
                          .Where(x => x != "")

    It can’t deal with any sentence using an interpolated string, but it’ll easily deal with this:

    var result = _context.Humans
                          .Select(x => "Name " +  x.Name + " Age " + x.Age)
                          .Where(x => x != "")

    The most painful thing is to fix bugs after turning on ClientEvaluation (exception for client-side calculation), since all Automapper profiles should be strictly analyzed for interpolation. Let’s find out what’s what and propose our solution to the problem.

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  • Hack the JWT Token

    • Tutorial

    For Educational Purposes Only! Intended for Hackers Penetration testers.


    The algorithm HS256 uses the secret key to sign and verify each message. The algorithm RS256 uses the private key to sign the message and uses the public key for authentication.

    If you change the algorithm from RS256 to HS256, the backend code uses the public key as the secret key and then uses the HS256 algorithm to verify the signature. Asymmetric Cipher Algorithm => Symmetric Cipher Algorithm.

    Because the public key can sometimes be obtained by the attacker, the attacker can modify the algorithm in the header to HS256 and then use the RSA public key to sign the data.
    The backend code uses the RSA public key + HS256 algorithm for signature verification.


    Vulnerability appear when client side validation looks like this:

    const decoded = jwt.verify(
       { algorithms: ['HS256'  , 'RS256'] }          //accepted both algorithms 

    Lets assume we have initial token like presented below and " => " will explain modification that attacker can make:

    alg: 'RS256'                         =>  'HS256'
    sub: '123',
    name: 'Oleh Khomiak',
    admin: 'false'                       => 'true'

    The backend code uses the public key as the secret key and then uses the HS256 algorithm to verify the signature.
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  • The most common OAuth 2.0 Hacks

      OAuth 2 overview

      This article assumes that readers are familiar with OAuth 2. However, below a brief description of it is presented below.

      1. The application requests authorization to access service resources from the user. The application needs to provide the client ID, client secret, redirect URI and the required scopes.
      2. If the user authorizes the request, the application receives an authorization grant
      3. The application requests an access token from the authorization server by presenting authentication of its own identity, and the authorization grant
      4. If the application identity is authenticated and the authorization grant is valid, the authorization server issues the access and refresh (if required) token to the application. Authorization is complete.
      5. The application requests the resource from the resource server and presents the access token for authentication
      6. If the access token is valid, the resource server serves the resource to the application

      The are some main Pros and Cons in OAuth 2.0

      • OAuth 2.0 is easier to use and implement (compared to OAuth 1.0)
      • Wide spread and continuing growing
      • Short lived Tokens
      • Encapsulated Tokens

      — No signature (relies solely on SSL/TLS ), Bearer Tokens
      — No built-in security
      — Can be dangerous if used from not experienced people
      — Too many compromises. Working group did not make clear decisions
      — Mobile integration (web views)
      — Oauth 2.0 spec is not a protocol, it is rather a framework — RFC 6749

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    • Web and Azure Tool Updates in Visual Studio 2019

        Hopefully by now you’ve seen that Visual Studio 2019 is now generally available. As you would expect, we’ve added improvements for web and Azure development. As a starting point, Visual Studio 2019 comes with a new experience for getting started with your code and we updated the experience for creating ASP.NET and ASP.NET Core projects to match:

        If you are publishing your application to Azure, you can now configure Azure App Service to use Azure Storage and Azure SQL Database instances, right from the publish profile summary page, without leaving Visual Studio. This means that for any existing web application running in App Service, you can add SQL and Storage, it is no longer limited to creation time only.

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      • Web application firewalls

        Web application firewall

        Web application firewalls (WAFs) are a type of intrusion detection and prevention system and might be either a hardware or software solution. It is specifically designed to inspect HTTP(s) and analyse the GET and POST requests using the appalling detection logic explained below. Web application firewall software is generally available as a web server plugin.

        WAF has become extremely popular and various companies offer a variety of solutions in different price categories, from small businesses to large corporations. Modern WAF is popular because it has a wide range of covered tasks, so web application developers can rely on it for various security issues, but with the assumption that this solution cannot guarantee absolute protection. A basic WAF workflow is shown below.

        Its main function is the detection and blocking of queries in which, according to WAF analysis, there are some anomalies, or an attacking vector is traced. Such an analysis should not make it difficult for legitimate users to interact with a web application, but, at the same time, it must accurately and timely detect any attempted attack. In order to implement this functionality, WAF developers usually use regular expressions, tokens, behavioural analysis, reputation analysis and machine learning, and, often, all these technologies are used together.

        In addition, WAF can also provide other functionality: protection from DDoS, blocking of IP-addresses of attackers, tracking of suspicious IP-addresses, adding an HTTP-only flag to the cookie, or adding the functionality of CSRF-tokens. Each WAF is individual and has a unique internal arrangement, but there are some typical methods used for analysis.
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