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NSM Web Server HTTP TRACE Method Enables Cross-Site Tracing Vulnerability

 [JSA10452] Show Article Properties

Legacy Advisory Id:
PSN-2010-08-895
Product Affected:
NSMXpressNSM3000NSM Appliance
Problem:


The web server in NSM supports the HTTP TRACE method. When the HTTP TRACE method is enabled, the web server echoes back all information sent to it by the client, typically for debugging or other diagnostic purposes.

An attacker who has created or inserted malicious instructions into a web page can cause a web browser to send trace requests to an affected web server, thus causing it to echo the web traffic back to the client system. The reflected traffic will include any authentication credentials that were transmitted in the forward traffic. The credentials can be recovered and exploited to gain unauthorized access to the affected system.

Disabling the HTTP TRACE method removes the vulnerability described above.
Solution:

This issue is fixed by "NSM Appliance Generic Offline Upgrade Package_v3 - CentOS 5.x" or "NSM Appliance Generic Online Upgrade Script_v3_CentOS5.x" (released Sep 30, 2014) or later.

These are available for download from https://www.juniper.net/support/downloads/?p=nsm#sw.

A viable workaround can be applied with the instructions described in "KB 14959: How to disable the web server HTTP TRACE method on NSMXpress" and duplicated below.

This is a zero-day issue that affects all versions of all NSM products except NSM Server. Note that NSM Server does not include the possibly-affected web server, and depends on the web server supplied and maintained separately on the customer's own host system. The web server in such systems may or may not be affected. Customers using NSM Server are encouraged to investigate independently to determine if the web server has the HTTP TRACE method available and enabled, and take corrective action if necessary.

Workaround:

To disable the HTTP TRACE method:
  1. Login as admin and enter "sudo su - root" on the NSM system.
  2. Use "vi" to edit the /etc/httpd/conf/httpd.conf file.
  3. If it is not already present, then add the following line at the end of the file:
            TraceEnable off
  4. Restart the httpd process with "/etc/init.d/httpd restart" or reboot the device.
After the change has been made, any attempt to request HTTP TRACE should return a "403 Forbidden" error message, and text transmitted by the client browser should not be echoed back automatically by the web server.
Implementation:
NSM Maintenance Releases are available at http://support.juniper.net/ from the "Download Software" links. If a Maintenance Release is not adequate and access to NSM patches is needed, open a customer support case. A JTAC engineer will review your request and respond, ensuring that you will be provided with the most appropriate Patch Release for your specific situation.

Also please note, as stated above, that NSM Server does not include the possibly-affected web server. Investigating and correcting the web server in such a situation is the responsibility of the customer.

Modification History:
2010-11-08: Initial publication.
2015-04-17: Updated solution.
Related Links:
CVSS Score:
5.0 (AV:N/AC:L/Au:N/C:P/I:N/A:N)
Severity Level:
Medium
Severity Assessment:
Information for how Juniper Networks uses CVSS can be found at "KB 16446 Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories".
Acknowledgements: