Vulnerability Note VU#366544
Adtrustmedia PrivDog fails to validate SSL certificates
Original Release date: 23 Feb 2015 | Last revised: 26 Feb 2015

Overview
Adtrustmedia PrivDog fails to validate SSL certificates, making systems broadly vulnerable to HTTPS spoofing.

Description
Adtrustmedia PrivDog is a Windows application that advertises "… safer, faster and more private web browsing." Privdog installs a Man-in-the-Middle (MITM) proxy as well as a new trusted root CA certificate. The MITM capabilities are provided by NetFilterSDK.com. Although the root CA certificate is generated at install time, resulting in a different certificate for each installation, Privdog does not use the SSL certificate validation capabilities that the NetFilter SDK provides. This means that web browsers will not display any warnings when a spoofed or MITM-proxied HTTPS website is visited. We have confirmed that PrivDog version 3.0.96.0 is affected.
Adtrustmedia PrivDog is promoted by the Comodo Group, which is an organization that offers SSL certificates and authentication solutions.

Users can test whether they are vulnerable to the PrivDog vulnerability and other similar vulnerabilities by visiting Filippo Valsorda’s SSL test page.

Impact
An attacker can spoof HTTPS sites and intercept HTTPS traffic without triggering browser certificate warnings in affected systems.

Solution
Apply an update

This issue is addressed in PrivDog 3.0.105.0. This version of PrivDog appears to disable SSL interception for connections where the upstream certificate is not valid. Alternatively, consider the following workaround:
Uninstall PrivDog

Uninstalling PrivDog will remove the MITM proxy and the root CA certificate, thus restoring SSL validation to affected systems.

Vendor Information (Learn More)

VendorStatusDate NotifiedDate UpdatedAdTrustMediaAffected-23 Feb 2015
COMODO Security Solutions, Inc.Not Affected23 Feb 201526 Feb 2015
NetFilterSDK.comUnknown-23 Feb 2015If you are a vendor and your product is affected, let
us know.

CVSS Metrics (Learn More)

Group
Score
Vector

Base
8.5
AV:N/AC:L/Au:N/C:C/I:P/A:N

Temporal
8.1
E:H/RL:W/RC:C

Environmental
8.0
CDP:ND/TD:ND/CR:ND/IR:ND/AR:ND

References

https://blog.hboeck.de/archives/865-Software-Privdog-worse-than-Superfish.html
https://blog.hboeck.de/archives/866-PrivDog-wants-to-protect-your-privacy-by-sending-data-home-in-clear-text.html
http://netfiltersdk.com/help/ProtocolFilters/FT_SSL.htm
http://www.privdog.com/advisory.html
http://www.privdog.com/
https://help.comodo.com/topic-72-1-451-6840-.html
https://help.comodo.com/topic-120-1-279-6108-.html
https://filippo.io/Badfish/
https://www.eff.org/deeplinks/2015/02/dear-software-vendors-please-stop-trying-intercept-your-customers-encrypted

Credit

This vulnerability was publicly reported by Hanno Böck.
This document was written by Will Dormann.

Other Information

CVE IDs:
Unknown

Date Public:
22 Feb 2015

Date First Published:
23 Feb 2015

Date Last Updated:
26 Feb 2015

Document Revision:
70

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