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Protocol for communication between iframe and the main window

Reading time4 min
Views5.2K
Waves corporate blogJavaScript * TypeScript * Website development *
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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Total votes 13: ↑12 and ↓1+11
Comments2

Let's help QueryProvider deal with interpolated strings

Reading time5 min
Views1.7K
.NET * C# * Programming * Designing and refactoring * Website development *
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 != "")
                      .ToList();

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 != "")
                      .ToList();

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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Total votes 12: ↑11 and ↓1+10
Comments0

Hack the JWT Token

Reading time4 min
Views64K
Information Security * Web services testing * Website development *
For Educational Purposes Only! Intended for Hackers Penetration testers.

Issue


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.

Example


Vulnerability appear when client side validation looks like this:

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

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

//header 
{
alg: 'RS256'                         =>  'HS256'
}
//payload
{
sub: '123',
name: 'Oleh Khomaik',
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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Total votes 12: ↑10 and ↓2+8
Comments0

The most common OAuth 2.0 Hacks

Reading time6 min
Views41K
Information Security * Website development * Web services testing *

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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Total votes 18: ↑17 and ↓1+16
Comments2

Web and Azure Tool Updates in Visual Studio 2019

Reading time2 min
Views923
Microsoft corporate blogWebsite development * Visual Studio * Microsoft Azure *

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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Total votes 11: ↑11 and ↓0+11
Comments0

Web application firewalls

Reading time6 min
Views4.1K
Amazon Web Services * Information Security * CyberpunkWebsite development *
From sandbox

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.
Read more →
Total votes 15: ↑13 and ↓2+11
Comments0

A Simple Way to Talk To Your Website

Reading time5 min
Views2K
Website development * CSS * API *
From sandbox
image

Technology and markets are going hand in hand today. It's going so close that any whiff of a tech headway and social media is going up in a frenzy about it. Writers are filling pages after pages as if it's already here. Shares ride bull or bear, and newspapers print a string of capital letters.
Read More
Total votes 14: ↑14 and ↓0+14
Comments1
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