Apache Web Server ETag Header Information Disclosure

[rkalapala]

Hi,

We wanted to disable ETag header information in our SAS mid tier, please help.

[Kurt_Bremser]

Add

<IfModule headers_module>
  Header unset Etag
  FileETag none
</IfModule>

to /.../Lev1/Web/WebServer/conf/httpd.conf and restart the web server.

Reference:

http://www.websiteoptimization.com/secrets/advanced/configure-etags.html

Disclaimer: I have no idea if or how that might affect the SAS webapps.

[rkalapala]

Thank you for your solution, it didn't help. I am still getting ETag information.

[alexal · Accepted solution]

@rkalapala,

What exactly is not working? Have you restarted the web server? You can try to add "Header unset Etag" without any "if" conditions.

[rkalapala]

@alexal

Actually we wanted to remove Etag header information, I tried to add without if and with if, still it is displaying the Etag header information. I restarted Web Server after update.

Thank you 

[alexal]

@rkalapala,

That should work, but let me ask you, why are you wanted to remove Etag header information? We do not recommend making to do any changes in http.conf, unless they were suggested by technical support. What are you trying to achieve?

[rkalapala]

@alexal

Our security team found that Apache Server ETag Header Information Disclosure, we have been asked to remediate, so we are disabling the Etag.

By the way your solution worked.

[JuanS_OCS]

@alexal,

on most of the big companies, or companies where security is not a must, but also there are audit procedures, they have periodic checks specially meant for the web applications, where alarms may raise, such as the Poodle and others related to SSL.

As consultant, I received several request on several clients to close this vulnerability. Of course, for the first request, I did my homework checking with SAS Technical Support. Once I had the green light, I did the change and some validations, no problem.

I feel curious: how come that this vulnerability is not included in https://support.sas.com/en/security-bulletins.html and not included on a hotfix? Is it in use by any SAS Web application?

[alexal]

@JuanS_OCS,

I do not have any details about this vulnerability, but I would suggest to open a technical support track and request that information. We have a specific procedure that we need to follow when contacting Product Security Incident Response Team (PSIRT), so only this team can respond.

[Kurt_Bremser]

Have a look at https://communities.sas.com/t5/SASware-Ballot-Ideas/Keep-3rd-party-software-current/idi-p/355959, where I suggested that SAS should keep the third-party web server software (apache and tomcat, both open-source) up-to-date, better than it is doing now.

[Kurt_Bremser]

How did you restart the web server? I recommend using

/..../Lev1/Web/WebServer/bin/httpdctl stop

(issued as the SAS install user)

then check if no httpd process is still running (ps -e|grep httpd)

and then issue

/..../Lev1/Web/WebServer/bin/httpdctl start

(again as SAS install user)

[rkalapala]

@Kurt_Bremser

I restarted web server as same way as recommended.

/..../Lev1/Web/WebServer/bin/httpdctl stop

/..../Lev1/Web/WebServer/bin/httpdctl start

Thank you for your help