Showing posts with label Startups. Show all posts
Showing posts with label Startups. Show all posts

Monday, August 27, 2018

Hello, Startup - A book for developers building their startups

Developers looking to build their startups should read this book

This is a book that I really recommend and wish developers and non-technical people would read: hello, startup. It has lots of insights not only on startups but also on careers, business, management, culture, handling success, failures and more, way more.

Quoting the author:
This book will teach you how to build products, technologies, and teams in a startup environment. It's based on the experiences of the author, Yevgeniy (Jim) Brikman, as well as interviews with programmers from some of the most successful startups of the last decade, including Google, Facebook, LinkedIn, Twitter, GitHub, Stripe, Instagram, AdMob, Pinterest, and many others.

If you're at all interested in startups, this book is for you.


If you're planning on building your own company, want to know more about the startup scene, is searching for answers regarding your current job and think that a startup may be your best choice, please take a look.

See Also

Monday, October 16, 2017

Securing your front-end

How secure is your front-end and how much could it be? Let's discuss it on this post.

An extremely common and dangerous flaw in web apps security is relying solely in client side security as we already discussed on this blog here and here. On this post we’ll examine the most frequent mistakes developers make and how to protect from them. But before we proceed, check our previous discussions on web application security. For all the topics on security, please click here.

Law of Security #4

We already reviewed the 10 laws of security on this blog. So, you may recall our Law #4:
If you allow a bad guy to upload programs to your Web site, it’s not your website any more.
That's probably, the main (but not the only) reason why web applications are so insecure: users are constantly submitting data to your application and changing data state. So what should we do? 
Should you trust all data being submitted to you?

Can you trust data from cookies sent to you?

Can you trust everything that you are getting in your web application layer?
Of course not.

You cannot trust client side security

Because you don’t have control of what runs on your client or how that information is being submitted - if it was manipulated or came from a different source than you expect - you should never trust the data you are getting in a request. That's why you should always re-validate in your server data sent to you. The only actual info you should trust is the session, stored on the server.

So what are the most common mistakes?

In the context of web applications, the most common mistakes web developers make are:
  • Hiding info in hidden fields
  • Relying on Http cookies
  • Relying on Url parameters
  • Using Form action urls for backend logic
  • Using the Referer header for backend logic
  • Trying to be cryptic or to obfuscate info
  • Rely purely on the ASP.Net Viewstate
  • Rely only on html form attributes
  • Only run Javascript validation

Mistake #1 - Hiding info in hidden fields

In the past, developers used to hide essential information in hidden form fields as:
<input type=”hidden” name=”price” value=”45”>
So when a post was submitted to the server, something like the below would be sent:
POST /page.aspx HTTP/1.1
Content-Type: application/x-www-form-urlencoded
Content-Length: 20
Hacking this application is as simple as:
  1. changing the price value using devtools and resubmitting the form;
  2. issuing a post from a different tool to the server.
Luckily, this anti-pattern is no longer common anymore.


The solution here is simlpy not use hidden fields to pass sensitive information to the client. Use the Id of the product or some other type of identifier instead.

Mistake #2 - Relying on HTTP cookies

This one is less common but is still being used. Developers are still saving sensitive information in cookies, which are stored in the client side and can be easily manipulated. Consider this response from the server:
HTTP/1.1 200 OK
Set-Cookie: Discount=20
Content-Length: 100
Assuming that the Discount value set in the cookie was used to perform some calculation in the server, a malicious user could easily change that information to 100 for example, and get the product for free. Not what we want.
POST /store.aspx HTTP/1.1 
Cookie: Discount=100
Content-Length: 10


The solution here is simlpy not use cookies fields to exchange/store sensitive information to the client. If you need to save, save it on the session, on the server. Upon each request, get the session value and process it from there.

Mistake #3 - Relying on Url parameters

Often, urls are very easily hackeable:
Anyone using a web browser or curl for example could alter that url and, if that property was used to provide the price to the server, alter it and benefit from your security issue. Others can be more obscure but also open to attacks:
 Remember that security trough obscurity does not work flawlessly.


Avoid using the query string to pass sensitive information. Even if some urls are meant to be hackeable, that's not the objective here.

Mistake #4 - Using Form action urls for backend logic

Similar to mistake #3, hidden but still modifiable, form actions can also be used to pass information :
<form action="/store/submit?discount=10">
Remember, this approach could be easily manipulated.


Avoid using the query string to pass sensitive information. Even if some urls are meant to be hackeable, that's not the objective here.

Mistake #5 - Using the Referer header for backend logic

Less common, the Http Referer header can be used to simulated authentication logic in the server. For example, a request like:
GET /auth/CreateUser.aspx HTTP/1.1
Could be interpreted in the server that the user indeed came from the admin page. While this could be true for non-malicious requests, it could also be manipulated.


Avoid using the Referer for authentication as can be easily manipulated in the client side.

Mistake #6 - Trying to be cryptic or to obfuscate info

We already provided an example in mistake #3. Trying to be cryptic or obfuscating information is not a 100% reliable solution. Yes, it could be used as part of a solution but should not be the sole solution.


Be creative securing your services and avoid security trough obscurity.

Mistake #7 - Rely only on html form attributes

Html form attributes like maxlength and disabled are nice but can be easily circumvented by simply removing them in developer tools or by submitting. Example:


Keep using those components to provide more friendlier applications but never rely only on them to validate your data. Always have similar validation in the server and in the backend if necessary.

Mistake #8 - Only run Javascript validation

As in mistake #8, relying solely on javascript is highly insecure as javascript can be disable or be easily removed, altered or manipulated in the client machine.


Make use of javascript to serve more friendlier applications but never rely only on it to validate your data. Always have similar validation in the server and in the backend if necessary.


So there you are, hope this post has helped you identifying the threats your app may be facing and how you could protect against them. But only for your front end. Remember, security is complicated. Securing your frontend is just another piece in the complex effort towards a good security framework.

See Also

  For more posts about ASP.NET on this blog, please click here.

Monday, October 2, 2017

Interview questions for QA analysts

Hiring a QA engineer? Here are some ideas.

We were asked to provide feedback on what I would like to see in a potential QA analyst. Apart from the traditional and essential HR screening (which they know way better than us) this post is about what I would like to see in a QA engineer working in my team.

Conceptual / Basic Questions

Before everything, we're interested in knowing if the person has solid understanding on why that work is being done, why it's important and how to get good results out of it. So, we would like to know, for example:
  • In your understanding, what are the benefits of QA?
  • In your opinion, what is the role of a QA analyst in a project development?
  • What is severity and priority of a bug? Give examples;
  • Define bug triage;
  • Expect some sort of calculation using severity, number of tests, dependent tasks, etc;
  • How to Estimate Testing effort;

Define why do we test software?

Expect the answer to include thinks like:
  • the process of assuring that the product being developed is meeting all requirements.
  • the reason to perform testing is to find bugs and make sure that they get fixed.

Why do we do QA?

Expect the answer to include thinks like:
  • to find the bugs before the product is released to customer.
  • to improve the quality of the product
  • to evaluate that the product is according to requirements

When is it the best moment to start QA in a project?

Expect the answer to include thinks like:
  • A good time to start the QA is from the beginning of the project startup.
  • This will lead to plan the process which will make sure that product coming out meets the customer quality expectation.
  • QA also plays a major role in the communication between teams. It gives time to step up the testing environment.
  • The testing phase starts after the test plans are written, reviewed and approved.

What are the key challenges of software testing?

Expect the answer to include thinks like:
  • Application should be stable enough to be tested.
  • Testing always under time constraint
  • Understanding requirements, Domain knowledge and business user perspective understanding
  • Which tests to execute first?
  • Testing the Complete Application
  • Regression testing
  • Lack of skilled testers.
  • Changing requirements
  • Lack of resources, tools and training

Define a testing lifecycle?

There is no standard testing life cycle, but I like to have following phases and would expect some (if not all) of them being mentioned:
  • Test Planning (Test Strategy, Test Plan, Test Bed Creation)
  • Test Development (Test Procedures, Test Scenarios, Test Cases)
  • Test Execution
  • Result Analysis (compare Expected to Actual results)
  • Defect Tracking
  • Reporting

List different types of tests

I expect at least 5 of the following:
  • Manual testing
  • Smoke testing
  • Regression testing
  • Automated testing
  • Stress Test
  • Load Test
  • Performance Test
  • Exploratory Testing

Programming Skills

For me, developers (as sysadmins/devops engineers), would do their job way more efficiently if they knew how to programm. If she knows how to program, then I would ask:
  • to write a simple function that would, for example, write a string backwards;
  • if the person knows html, css? Exercise that a little;
  • does the person know how to hit a restful api to use browserstack, for example;
  • does the person know javascript;
  • does the person know some other scriptting language so he/she would be able to write some automation;

SQL / NoSQL Questions

I would also very interested in knowing if the person knows SQL. Not necessarily super well but well enough to deal with basic sql instructions and be independent. Also, in case you use NoSQl, ability to query your db in your query language like for example, MongoDb's query syntax or Lucene.

Software Automation Questions

In order to maximize the return of a QA in the team, test automation is a must. That said, the person needs to have enough programming skills write reproducible tests using selenium for example. Personally, I would like to know if the person: 
  • thinks automation is important?
  • knows when to automate?
  • knows what are the benefits of automating?
  • knows what are the downsides of automating?
  • have written automated tests?
  • have used selenium?
Having already working selenium is a big advantage for me.

Infrastructure Questions

Expect the answer to include thinks like:
  • What's the difference between a build and a release?
  • Yes, I have used Azure or AWS before;
  • Yes, I know how to use ftp;
  • Yes, I know how to you check if a server is up;
  • have previously used git, github?
  • have previously you/written a wiki?
  • have previously used Firebug / Chrome Dev tools 
  • is able to inspect, communicate js/html issues;

Board/Offline Exercise

While I don't think we should always use the board, it would be interesting to use the board to check how the person would improvise on two scenarios:

Scenario 1 - Write a test document based on a real use case

In this scenario, I would present a simple use case such as how to create an account on my system (please, use a simple enough for your own system):
  1. Navigate to the landing page of my site;
  2. Click on the Register button;
  3. Enter essential information to create account;
Then, ask user to:
  • List what he/she would have validated?
  • What boundary tests could be written?
  • Ask user to write test matrix;

Scenario 2 - Write a bug report

Still on the create account use case, let's assume that the system should email the new user a confirmation token but it didn't. I then would be interested in:
  • How would the person write a report in case the email didn't reach your inbox? 
  • If the person would document simple stuff as:
    • Date of the test, url, browser version, etc;
    • Steps:
      • clicked on button X;
      • Entered the following info...;
      • Clicked submit;
    • Expected result;
    • Actual result;
That is what I, as a developer, would like to see in a basic bug reported: enough information to reproduce and fix the test. Less than that may be insufficient to reproduce it meaning the probably   the candidate is not a good fit.


I consider the following, differential to have:
  • Selenium/Automation experience;
  • Cloud experience;
  • Being able to discuss technical details with the developer
  • Linux/MacOS experience;


So, this is all that came to my mind. There's probably more to it but I think that the list above covers a good, very strong candidate. Note that this is by no means a checklist but how I describe a very strong QA candidate and I would be very happy to have someone with the above skills in my team.

About the Author

Bruno Hildenbrand      
Principal Architect, HildenCo Solutions.