The Web Application Hacker’s Handbook Discovering and Exploiting Security Flaws

Review the HTML source code for any forms that contain text fields in

which sensitive data is captured.

■

If the attribute 

autocomplete=off

is not set, either within the form tag

or the tag for the individual input field, then data entered will be stored

within browsers where autocomplete is enabled. 

Preventing Local Privacy Attacks

Applications should avoid storing anything sensitive in a persistent cookie.

Even if this data is encrypted, it can be resubmitted by an attacker who cap-

tures it.

Applications should use suitable cache directives to prevent sensitive data

from being stored by browsers. In ASP applications, the following instructions

will cause the server to include the required directives:

<% Response.CacheControl = “no-cache” %>

<% Response.AddHeader “Pragma”, “no-cache” %>

<% Response.Expires = 0 %>

In Java applications, the following commands should achieve the same

result:

<%

response.setHeader(“Cache-Control”,”no-cache”);

response.setHeader(“Pragma”,”no-cache”);

response.setDateHeader (“Expires”, 0);

%>

Applications should never use URLs to transmit sensitive data, as these are

liable to be logged in numerous locations. All such data should be transmitted

using HTML forms that are submitted using the 

POST

method.