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Testing for Sensitive Information Sent via Unencrypted Channels



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 mechanism must not have limitations or vulnerabilities, as explained in the broader article Testing for Weak Transport Layer Security and in other OWASP documentation:

As a rule of thumb if data must be protected when it is stored, this data must also be protected during transmission. Some examples for sensitive data are:

  • Information used in authentication (e.g. Credentials, PINs, Session identifiers, Tokens, Cookies…)
  • Information protected by laws, regulations or specific organizational policy (e.g. Credit Cards, Customers data)

If the application transmits sensitive information via unencrypted channels - e.g. HTTP - it is considered a security risk. Attackers can take over accounts by sniffing network traffic. Some examples are Basic authentication which sends authentication credentials in plain-text over HTTP, form based authentication credentials sent via HTTP, or plain-text transmission of any other information considered sensitive due to regulations, laws, organizational policy or application business logic.

Examples for Personal Identifying Information (PII) are:

  • Social security numbers
  • Bank account numbers
  • Passport information
  • Healthcare related information
  • Medical insurance information
  • Student information
  • Credit and debit card numbers
  • Driver’s license and State ID information

Test Objectives

  • Identify sensitive information transmitted through the various channels.
  • Assess the privacy and security of the channels used.

How to Test

Various types of information that must be protected, could be transmitted by the application in clear text. To check if this information is transmitted over HTTP instead of HTTPS, capture traffic between a client and web application server that needs credentials. For any message containing sensitive data, verify the exchange occurred using HTTPS. See more information about insecure transmission of credentials OWASP Top 10 2017 A3-Sensitive Data Exposure or Transport Layer Protection Cheat Sheet.

Example 1: Basic Authentication over HTTP

A typical example is the usage of Basic Authentication over HTTP. When using Basic Authentication, user credentials are encoded rather than encrypted, and are sent as HTTP headers. In the example below the tester uses curl to test for this issue. Note how the application uses Basic authentication, and HTTP rather than HTTPS.

$ curl -kis
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-Based Authentication Performed over HTTP

Another typical example is authentication forms which transmit user authentication credentials over HTTP. In the example below one can see HTTP being used in the action attribute of the form. It is also possible to see this issue by examining the HTTP traffic with an interception proxy.

<form action="">
    <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"/>

The Session ID Cookie must be transmitted over protected channels. If the cookie does not have the secure flag set, it is permitted for the application to transmit it unencrypted. Note below the setting of the cookie is done without the Secure flag, and the entire log in process is performed in HTTP and not HTTPS.

POST /login HTTP/1.1
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
Set-Cookie: JSESSIONID=BD99F321233AF69593EDF52B123B5BDA; expires=Fri, 01-Jan-2014 00:00:00 GMT; path=/;; httponly
Location: private/
Content-Length: 0
Content-Type: text/html

GET /private HTTP/1.1
Cookie: JSESSIONID=BD99F321233AF69593EDF52B123B5BDA;

HTTP/1.1 200 OK
Content-Type: text/html;charset=UTF-8
Content-Length: 730
Date: Tue, 25 Dec 2013 00:00:00 GMT

Example 4: Password Reset, Change Password or Other Account Manipulation over HTTP

If the web application has features that allow a user to change an account or call a different service with credentials, verify all of those interactions use HTTPS. The interactions to test include the following:

  • Forms that allow users to handle a forgotten password or other credentials
  • Forms that allow users to edit credentials
  • Forms that require the user to authenticate with another provider (for example, payment processing)

Example 5: Testing Password Sensitive Information in Source Code or Logs

Use one of the following techniques to search for sensitive information.

Checking if password or encryption key is hardcoded in the source code or configuration files.

grep -r –E "Pass | password | pwd |user | guest| admin | encry | key | decrypt | sharekey " ./PathToSearch/

Checking if logs or source code may contain phone number, email address, ID or any other PII. Change the regular expression based on the format of the PII.

grep -r " {2\}[0-9]\{6\} " ./PathToSearch/


Use HTTPS for the whole web site and redirect any HTTP requests to HTTPS.