Vulnerability Note VU#534407
Barracuda Web Filter insecurely performs SSL inspection
Original Release date: 28 Apr 2015 | Last revised: 28 Apr 2015

Overview
Barracuda Web Filter prior to version 8.1.0.005 does not properly check upstream certificate validity when performing SSL inspection, and delivers one of three default root CA certificates across multiple machines for SSL inspection.

Description
According to Barracuda Networks, the Barracuda Web Filter is a "comprehensive solution for web security and management" with many features, including the ability to provide "visibility into SSL-encrypted traffic". This SSL inspection feature of the Barracuda Web Filter is vulnerable to multiple issues.
Incomplete validation of upstream certificate validity – CVE-2015-0961

Barracuda Web Filter versions between 7.0 and 8.1.0.005 do not check upstream certificate validity when performing SSL inspection.

Shared root CA certificate – CVE-2015-0962

Barracuda Web Filter versions between 7.0 and 8.1.0.005 ship one of three different default certificates that are shared across multiple machine for use in the SSL Inspection feature.

Users who have configured SSL Inspection on a Barracuda Web Filter may be affected. Beginning in version 8.1.0.005, Barracuda Web Filter verifies certificate validity and generates a unique default certificate for each appliance.

Barracuda Networks has released a security advisory with more details. For more information on the impact of these issues on SSL inspection, please see Will Dormann’s CERT/CC blog post on SSL Inspection.

The CVSS score below is based on CVE-2015-0962.

Impact
The impact of either CVE-2015-0961 or CVE-2015-0962 may allow an attacker to successfully achieve a man-in-the-middle (MITM) attack without the client knowing it.

Solution
Update the firmware

Barracuda Networks has released firmware version 8.1.0.005 on April 16th, 2015 to address these issues. Affected users should upgrade to firmware 8.1.0.005 or later as soon as possible.

Users who have deployed an affected service using the default certificate supplied with the appliance will need to deploy a new client certificate to their clients and remove the previously deployed certificate. Instructions for deploying and removing client certificates are available at http://techlib.barracuda.com/BWF/UpdateSSLCerts.

Check that old shared certificates are removed

Barracuda has also provided https://certcheck.barracudalabs.com, a site that will show users if their browser trusts any of the shared default certificates and includes instructions for removing the certificates from the browser trust store if necessary.

Vendor Information (Learn More)

VendorStatusDate NotifiedDate UpdatedBarracuda NetworksAffected-21 Apr 2015If you are a vendor and your product is affected, let
us know.

CVSS Metrics (Learn More)

Group
Score
Vector

Base
8.8
AV:N/AC:M/Au:N/C:C/I:C/A:N

Temporal
6.9
E:POC/RL:OF/RC:C

Environmental
5.2
CDP:ND/TD:M/CR:ND/IR:ND/AR:ND

References

http://cuda.co/15076
http://techlib.barracuda.com/BWF/UpdateSSLCerts
https://certcheck.barracudalabs.com
https://www.cert.org/blogs/certcc/post.cfm?EntryID=221

Credit

Thanks to Barracuda Networks for promptly addressing these issues and contacting the CERT/CC to coordinate disclosure.
This document was written by Garret Wassermann.

Other Information

CVE IDs:
CVE-2015-0961
CVE-2015-0962

Date Public:
28 Apr 2015

Date First Published:
28 Apr 2015

Date Last Updated:
28 Apr 2015

Document Revision:
27

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