9 January 2012
Those using this tutorial should have beginner knowledge of ColdFusion, and a basic understanding of cookies.
Cookies are a critical component to most ColdFusion web applications. Some cookies such as session identifier cookies (CFID, CFTOKEN, or JSESSIONID) contain sensitive information. If an attacker is able to read an end-user's session identifier cookies, he can impersonate the end-user (this is also known as session hijacking).
In this article, you'll learn about HttpOnly cookies, why they are important, and how you can leverage them to improve the security of your ColdFusion applications.
When the HttpOnly attribute is present in a
Set-Cookie HTTP response header from the server, the browser (if it supports the
Now, let's assume that your site has a cross-site scripting (XSS) vulnerability, which allows an attacker to execute arbitrary client-side code on your domain. In this case, your code might look like this:
<cfif NOT searchResults.recordcount> <cfoutput>Sorry no items matched your search: #url.query#</cfoutput> </cfif>
An attacker may now attempt to use this XSS hole to hijack sessions by sending your users to a uri like the following one:
Any cookies that you create with the
document.cookie variable. You'll be reading more about browser support in the next sections.
As you will see it's really quite simple to turn an existing cookie into an HttpOnly cookie. You can add this extra layer of protection to most of your applications in a very small amount of time.
As of ColdFusion 9.0, you can use the
httponly attribute in the
cfcookie tag which accepts a boolean value, for example:
<cfcookie name="example" value="secret" httponly="true">
The above code results in the server writing a HTTP response header that looks like the following:
Set-Cookie: EXAMPLE=secret; HttpOnly;path=/
Support for the HttpOnly cookie attribute has existed as far back as 2002 when Microsoft pioneered it in Internet Explorer 6 SP1. Five long years later, Firefox 18.104.22.168 was the first version to support HttpOnly in 2007. Safari and Chrome have followed suit, and support HttpOnly as well. The HttpOnly cookie attribute is defined in the RFC 6265 published in April 2011, currently in proposed standard status.
XMLHttpRequest (or AJAX) call, the attacker can read the value of the cookie in a
Set-Cookie HTTP response header on such browsers.
The security rule: "principle of least privilege" suggests that you make your cookies HttpOnly whenever it is possible for you to do so. Thus, I recommend that any cookie that you set through the
cfcookie tag use the
The secure cookie attribute instructs the browser to only transmit the cookie when a secure connection (for example a HTTPS/SSL connection) is present. If your web application supports or requires SSL, you may want to use the
secure cookie attribute to further improve security. ColdFusion has supported the
secure attribute on the
cfcookie since ColdFusion 3, and possibly earlier.
When secure session cookies are enabled your web application will only maintain sessions when HTTPS is used. When HTTPS is not used a new session will be created on each request.
Because session cookies contain very sensitive information, they are a prime candidate for adding the
httponly attribute. Below, I describe two common approaches to making your ColdFusion session cookies HttpOnly.
The ColdFusion 9.0.1 update added a server-wide setting to add the
httponly attribute to all session cookies created by ColdFusion (such as the
CFTOKEN cookies, or the
JSESSIONID cookie on JRun). To enable this setting, if you are running a JRun J2EE installation or multi-server installation, you must edit jvm.config, otherwise you can enable this setting from the CF Administrator. If you are running a J2EE server other than JRun consult your documentation for an appropriate setting. J2EE servers that support the Servlet 3.0 specification can specify
<session-config><cookie-config><http-only>true</http-only></cookie-config></session-config> in the /WEB-INF/web.xml file.
To enable this setting in a JRun J2EE installation or multi-server installation, you must define the following Java system property
coldfusion.sessioncookie.httponly and set it to
true . You can define Java system properties when the JVM is loaded by adding the following line:
If you have installed ColdFusion in J2EE or multi-server mode, system properties must be defined by editing the jvm.config file which is located in the bin directory under your JRun root directory in a default configuration.
If you are running ColdFusion Standard Edition, or Enterprise in stand-alone mode, you can enable this setting by defining the property in the ColdFusion administrator by following these steps:
-Dcoldfusion.sessioncookie.httponly=trueto the text box labeled JVM Arguments.
This approach makes it easy to add the
httponly attribute to session cookies in ColdFusion. If you use SSL you may want your session cookies to also use the
secure attribute. ColdFusion does not provide a mechanism to enable the secure attribute on session cookies, however JRun, and other servlet containers (such as Tomcat) do provide a such a mechanism. This requires that J2EE sessions are enabled in the ColdFusion administrator. To enable secure session cookies on JRun you must add
<cookie-secure>true</cookie-secure> to the jrun-web.xml file:
<jrun-web-app> <session-config> <cookie-config> <active>true</active> <cookie-secure>true</cookie-secure> </cookie-config> </session-config> </jrun-web-app>
You must restart ColdFusion / JRun for this change to be picked up.
Support for setting HttpOnly on a JSESSIONID cookie may vary if you are using a J2EE server other than JRun. Tomcat and JBoss require a native approach to set the HttpOnly attribute, this approach and the following approach may not work on all J2EE servers..
You may be in a scenario where the server wide HttpOnly setting is not enabled, or prefer to control exactly how session identifier cookies are created on a per Application basis. Please note however that the following approach does not work when J2EE sessions are enabled.
The ColdFusion Application setting
setClientCookies when set to
false prevents ColdFusion from automatically writing the session identifier cookies on session start. You can take advantage of that and write the cookies on your own in your
onSessionStart function. In the following Application.cfc example, the following code creates HttpOnly cookies for the
CFTOKEN session cookies:
<cfcomponent> <cfset this.sessionmanagement = true> <cfset this.setclientcookies = false> <cffunction name="onSessionStart"> <cfcookie name="CFID" value="#session.cfid#" httponly="true"> <cfcookie name="CFTOKEN" value="#session.cftoken#" httponly="true"> </cffunction> <cfcomponent>
One advantage of this approach is that you can also control the expiration of the session cookies. In other words, in the above example, in the
cfcookie tags, I have ommited the
expires attribute, which means that the cookies will expire when the end user closes the browser.
You can also use this technique on versions of ColdFusion prior to 9 but since
cfcookie doesn't support HttpOnly on prior versions, you must write the cookies by writing a
Set-Cookie header with
You should now have an understanding of what HttpOnly cookies are and why you should start using them. The added support for HttpOnly in ColdFusion 9 makes enabling using HttpOnly cookies much easier than with prior versions.
See the following resources for more information about HttpOnly cookies: