Get the basics right!

Hello World 2017

by Renato Rodrigues

Renato Rodrigues  



Web Apps
Out of the Box
Out There

Web Applications

What IS it?

In computing, a web application  or web app  is a client–server software application  which the client (or user interface) runs in a web  browser.


Modern Apps

Images from Google Images.

The Big Picture

Maybe we should know where they live!

We know that a modern Web App is a pile of technology.

How many stacks are being used?
The links between them?
Possible weaknesses

Can we understand:


Images from Alrra Browser-Logos.


Cross-site scripting (XSS)

Cross-site Request Forgery (CSRF)

SQL Injection (SQLi)

Remote Code Execution (RCE)

XML External Entity (XXE)

Session Fixation

Dir Traversal

Insecure Direct Object References

Broken Authentication and Session Management

Server Side Request Forgery (SSRF)

Unvalidated Redirects and Forwards

Insecure Cryptographic Storage

Relative Path Overwrite (RPO)




 Sets the configuration for the cross-site scripting filters built into most browsers. The best configuration is "X-XSS-Protection: 1; mode=block".

X-XSS-Protection 1; mode=block

Information from


Tells the browser whether you want to allow your site to be framed or not. By preventing a browser from framing your site you can defend against attacks like clickjacking.

X-Frame-Options SAMEORIGIN | DENY     

Information from


Stops a browser from trying to MIME-sniff the content type and forces it to stick with the declared content-type. This helps to reduce the danger of drive-by downloads. The only valid value for this header is "X-Content-Type-Options: nosniff".

X-Content-Type-Options nosniff

Information from


Is an "effective" measure to protect your site from several attacks. By whitelisting sources of approved content, you can prevent the browser from loading malicious assets.

Content-Security-Policy default-src 'self'; script-src 'self' ...

Information from

CSP Builder (Helper):       


Is an excellent feature to support on your site and strengthens your implementation of TLS by getting the User Agent to enforce the use of HTTPS.

Strict-Transport-Security max-age=31536000; includeSubdomains; preload        

Information from


Protects your site from MiTM attacks using rogue X.509 certificates.

By whitelisting only the identities that the browser should trust, your users are protected in the event a certificate authority is compromised.

Public-Key-Pins pin-sha256="t/OMbK...JM="; max-age=600; report-uri="..."

Information from

Subresource Integrity

Mechanism by which user agents may verify that a fetched resource has been delivered without unexpected manipulation.

<script src=""

Information from W3C.


Session, Secure, HTTPOnly and SameSite

Input Validation

Client and Server Side Always!

More to come: Suborigins, Referrer Policy, Expect-CT ...

Not out of box but...

Out There


// - // - // - //
Search for a Security Page

A bug bounty  program is a deal offered by many websites and software developers by which individuals can receive recognition and compensation for reporting bugs , especially those pertaining to exploits and vulnerabilities.


Discovery Date: dd/MM/YY - HH:mm:ss
Vulnerability Type: XSS / RCE / CSRF / ...
Description: Detailed explanation of the vulnerability 
Impact: In the context of the vulnerable service/app.

Proof of Concept Data (PoC)
* Works in: Google Chrome, Firefox, IE, Safari, ...
* Attack Vector: How to trigger the vulnerability.
* Payload: What triggers the vulnerability. 
PoC Image/Video: Visual proof.
Mitigation: If we have an idea how to fix, we should suggest.
Notes: If pertinent.        

Always remember to be polite!

It's Over!

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