Testing for Sensitive information sent via unencrypted channels (OTG-CRYPST-003)

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This article is part of the new OWASP Testing Guide v4.
Back to the OWASP Testing Guide v4 ToC: https://www.owasp.org/index.php/OWASP_Testing_Guide_v4_Table_of_Contents Back to the OWASP Testing Guide Project: https://www.owasp.org/index.php/OWASP_Testing_Project

Brief Summary

Sensitive data must be protected when it is transmitted through the network. If data is transmitted over HTTPS or encrypted in another way the protection mechanist must have not limitations and vulnerabilities, as explained in the broader article "Testing for Weak SSL/TSL Ciphers, Insufficient Transport Layer Protection" [1] and in other OWASP documentation [2], [3], [4], [5].In fact consider adding a security control or safeguard is an addition to the attack surface. However a specific test is needed to ensure if the control is missing and sensitive data is transmitted via unencrypted channel. As a rule of thumb if data must be protected when it is stored, it must be protected also during transmission. Such as:

  • Information used in Authentication (e.g. Credentials, PINs, Session Ids, Tokens, Cookies…)
  • Information protected by Laws, Regulations or specific Organization’s Policy (e.g. Credit Cards, Customers data)

Description of the Issue

If the application transmits sensitive information via unencrypted channels - e.g. HTTP - it is a vulnerability. Typically it is possible to find BASIC authentication over HTTP, input password sent via HTTP and, in general, other information considered by regulations, laws or organization policy.

Black Box testing and example

Various typologies of information, which must be protected, can be also transmitted in clear text. It is possible to check if this information is transmitted over HTTP instead of HTTPS. Please refer to specific Tests for full details, for credentials [3] and other kind of data [2].

Example 1. Basic Authentication over HTTP

A typical example is the usage of Basic Authentication over HTTP. Also, with Basic Autentication credentials are encoded and not encrypted into HTTP Headers, using curl [5].

$ curl -kis http://example.com/restricted/ 
HTTP/1.1 401 Authorization Required 
Date: Fri, 01 Aug 2013 00:00:00 GMT 
WWW-Authenticate: Basic realm="Restricted Area" 
Accept-Ranges: bytes Vary: 
Accept-Encoding Content-Length: 162 
Content-Type: text/html  

<html><head><title>401 Authorization Required</title></head> 
<body bgcolor=white> <h1>401 Authorization Required</h1>  Invalid login credentials!  </body></html>

Example 2. Form Authentication over HTTP

Another typical example is forms containing passwords transmitted over HTTP. It is possible to find the “http://” or “//” as the protocol in “action” attribute of the form and some input containing passwords or other data.

<form action="http://example.com/login">
	<label for="username">User:</label> <input type="text" id="username" name="username" value=""/><br />
	<label for="password">Password:</label> <input type="password" id="password" name="password" value=""/>
	<input type="submit" value="Login"/>

Example 3. Cookie containing Session ID over HTTP

Session ID Cookie must be transmitted over protected channels. If Cookie have NOT Secure flag [6] it is possible to transmit unencrypted. In this case it can be eavesdropped.


POST /login HTTP/1.1
Host: secure.example.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:25.0) Gecko/20100101 Firefox/25.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Referer: https://secure.example.com/
Content-Type: application/x-www-form-urlencoded
Content-Length: 188

HTTP/1.1 302 Found
Date: Tue, 03 Dec 2013 21:18:55 GMT
Server: Apache
Cache-Control: no-store, no-cache, must-revalidate, max-age=0
Expires: Thu, 01 Jan 1970 00:00:00 GMT
Pragma: no-cache
Set-Cookie: JSESSIONID=BD99F321233AF69593EDF52B123B5BDA; expires=Fri, 01-Jan-2014 00:00:00 GMT; path=/; domain=example.com; httponly
Location: private/
X-Content-Type-Options: nosniff
X-XSS-Protection: 1; mode=block
X-Frame-Options: SAMEORIGIN
Content-Length: 0
Keep-Alive: timeout=1, max=100
Connection: Keep-Alive
Content-Type: text/html


GET /private HTTP/1.1
Host: example.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:25.0) Gecko/20100101 Firefox/25.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Referer: https://secure.example.com/login
Cookie: JSESSIONID=BD99F321233AF69593EDF52B123B5BDA;
Connection: keep-alive

HTTP/1.1 200 OK
Cache-Control: no-store
Pragma: no-cache
Expires: 0
Content-Type: text/html;charset=UTF-8
Content-Length: 730
Date: Tue, 25 Dec 2013 00:00:00 GMT


OWASP Resources


  • [5] curl can be used to check manually for pages