Security of WEB-INF content

[Haledor wow <ha...@gmail.com>]

Hi,

I have read in various forums that there are situations where the content of
WEB-INF can be accessed. Some people say that it is good practice to hide
sensitive files in WEB-INF and some say it might not be...

I am using Tomcat 6.0 and I am worried someone could access some of my
sensitive files located inside the WEB-INF folder. Could you explain to me
whether this is possible or not. Do i need to obfuscate the content of the
files in WEB-INF?

With best regards,
Peter Hallbeck

Re: Security of WEB-INF content

[Christopher Schultz <ch...@christopherschultz.net>]

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Peter,

On 10/29/2010 7:57 AM, Mark Thomas wrote:
> On 29/10/2010 12:30, Haledor wow wrote:
>> Hi,
>>
>> I have read in various forums that there are situations where the content of
>> WEB-INF can be accessed. Some people say that it is good practice to hide
>> sensitive files in WEB-INF and some say it might not be...
>>
>> I am using Tomcat 6.0 and I am worried someone could access some of my
>> sensitive files located inside the WEB-INF folder. Could you explain to me
>> whether this is possible or not.
> 
> Nothing under WEB-INF is directly accessible to a user. Requests to
> http://host:port/app/WEB-INF/... will always be rejected.

If Tomcat is being used behind a web server such as Apache httpd, then
the web server can be used to subvert the security provided by Tomcat.

For example, a naive configuration might be:

httpd.conf:
DocumentRoot /var/www/my-webapp
JkMount /*.jsp worker

my-webapp.xml:
<Context docBase="/var/www/my-webapp" />

If a request comes in for /WEB-INF/web.xml, Apache httpd will happily
serve that file off the disk while the same request to Tomcat would fail.

There are many solutions to this problem, including:

1. Not using a fronting web server
2. Setting DocumentRoot != docBase
3. Adding <Limit> directives to httpd.conf to specifically
   exclude WEB-INF and other sensitive areas
4. Making WEB-INF and other sensitive areas unreadable
   by the httpd process
5. Use a more general (or additional) JkMount directives, like
   JkMount /*.jsp worker
   JkMount /WEB-INF/* worker
   ... though if you have a JkMount for /WEB-INF/, you may as
   well do #3 or #4 above.

I highly favor #1 and #2 above, though your environment may necessitate
some of the other options.

- -chris
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Re: Security of WEB-INF content

[Mark Thomas <ma...@apache.org>]

On 29/10/2010 12:30, Haledor wow wrote:
> Hi,
> 
> I have read in various forums that there are situations where the content of
> WEB-INF can be accessed. Some people say that it is good practice to hide
> sensitive files in WEB-INF and some say it might not be...
> 
> I am using Tomcat 6.0 and I am worried someone could access some of my
> sensitive files located inside the WEB-INF folder. Could you explain to me
> whether this is possible or not.

Nothing under WEB-INF is directly accessible to a user. Requests to
http://host:port/app/WEB-INF/... will always be rejected.

However, applications can forward requests to resources under /WEB-INF
and can also include resources under /WEB-INF. It is up to the
application to make sure it doesn't do that in a way that could
compromise the security of any sensitive data placed under /WEB-INF.

> Do i need to obfuscate the content of the
> files in WEB-INF?

No.

And as an aside, Obfuscation != security

Mark

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