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ESA-2010-015: EMC Celerra NFS authentication bypass vulnerability using IP
spoofing.

EMC Identifier: ESA-2010-015

CVE Identifier: CVE-2010-2860

Severity Rating: CVSS v2 Base Score: 8.3 (AV:A/AC:L/Au:N/C:C/I:C/A:C)


Affected products:

EMC SW: NAS Code 5.6.50 and earlier


Vulnerability Summary:
 
A vulnerability exists in EMC Celerra which can be exploited to gain
unauthorized access to root NFS export on EMC Celerra NAS.


Vulnerability Details: 

A vulnerability in EMC Celerra may allow an attacker to spoof IP addresses
that are normally used between the Celerra Control Station and X-Blade
(Data Mover) over a private IP network. While these IP addresses are
normally intended for communication internal to the Celerra, they are also
accepted from external sources. By spoofing these IP addresses, an attacker
may be able to gain unauthorized access to file systems on the Celerra. The
vulnerability only exists when the attacker and external IP of the Data
Mover are on the same subnet.

Problem Resolution: 
The following EMC Celerra products contain resolutions to this issue:

• EMC Celerra NAS Code 5.6.51

EMC strongly recommends all customers apply the latest patch, which
contains the resolution to this issue, at the earliest opportunity. 

Link to remedies:
 
Registered EMC Powerlink customers can download software from Powerlink.
For Celerra Software, navigate in Powerlink to Home > Support > Software
Downloads and Licensing > Downloads C > Celerra Software.
 
Because the view is restricted based on customer agreements, you may not
have permission to view certain downloads. Should you not see a software
download you believe you should have access to, follow the instructions in
EMC Knowledgebase solution emc116045.

Workaround:

1. Create IP-based access rules on the network equipment rejecting traffic
for IP addresses belonging to the internal Celerra network. These addresses
are listed in the /etc/hosts file of the Celerra Control Station. That
traffic should never be routed to the Control Station; the traffic remains
internal to the cabinet and has its own network switches for that purpose. 
2. Configure firewalls between Data Movers and NFS clients to reject
traffic for IP addresses belonging to the internal Celerra network. 
3. Hide the Data Mover's NFS exports from clients that do not have access
by setting the forceFullShowmount parameter to 0 (default is 1). This will
hide the " / " from the list since only the Control Station has access to
it (for administrative purposes). 
4. Disable IP reflect. 
5. Change the default IP addresses for the internal network of the Celerra
to a non-routable IP address scheme that does not conflict with any other
non-routable IP networks.

To implement Step 3 above, modify the forceFullShowmount parameter as
follows:

[root@virgil slot_3]# server_param server_3 -f mount -info
forceFullShowmount
server_3 : 
name                    = forceFullShowmount
facility_name           = mount
default_value           = 1
current_value           = 1
configured_value        = 
user_action             = none
change_effective        = immediate
range                   = (0,1)
description             = Forces response to showmount requests to fully
populate response.
[root@virgil slot_3]# server_param server_3 -f mount -modify \
forceFullShowmount -value 0
server_3 : done

After the above change, client will see only the shares he has permissions
to access to.

For explanation of Severity Ratings, refer to EMC Knowledgebase solution
emc218831.

Credits:  

EMC would like to thank Steve Ocepek of Trustwave's SpiderLabs for
reporting this issue.

EMC Corporation distributes EMC Security Advisories in order to bring to
the attention of users of the affected EMC products important security
information. EMC recommends all users determine the applicability of this
information to their individual situations and take appropriate action. The
information set forth herein is provided "as is" without warranty of any
kind. EMC disclaims all warranties, either express or implied, including
the warranties of merchantability, fitness for a particular purpose, title
and non-infringement. In no event shall EMC or its suppliers be liable for
any damages whatsoever including direct, indirect, incidental,
consequential, loss of business profits or special damages, even if EMC or
its suppliers have been advised of the possibility of such damages. Some
states do not allow the exclusion or limitation of liability for
consequential or incidental damages so the foregoing limitation may not
apply. 


EMC Product Security Response Center
Security_Alert@EMC.com
http://www.emc.com/contact-us/contact/product-security-response-center.htm
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