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Date: Mon, 25 Nov 2019 14:43:45 +0100
From: SEC Consult Vulnerability Lab <>
To: <>, <>
Subject: SEC Consult SA-20191125-0 :: FortiGuard XOR Encryption in Multiple
 Fortinet Products

SEC Consult Vulnerability Lab Security Advisory < 20191125-0 >
              title: FortiGuard XOR Encryption
            product: Multiple Fortinet Products (see Vulnerable / tested versions)
 vulnerable version: Multiple (see Vulnerable / tested versions)
      fixed version: Multiple (see Solution)
         CVE number: CVE-2018-9195
             impact: High
              found: 2018-05-16

                 by: Stefan Viehböck (Office Vienna)
                     SEC Consult Vulnerability Lab

                     An integrated part of SEC Consult
                     Europe | Asia | North America



Vendor description:
"From the start, the Fortinet vision has been to deliver broad, truly
integrated, high-performance security across the IT infrastructure.

We provide top-rated network and content security, as well as secure access
products that share intelligence and work together to form a cooperative
fabric. Our unique security fabric combines Security Processors, an intuitive
operating system, and applied threat intelligence to give you proven security,
exceptional performance, and better visibility and control--while providing
easier administration."


Business recommendation:
The vendor provides a patch and users of affected products are urged to
immediately upgrade to the latest version available.

Vulnerability overview/description:
Fortinet products, including FortiGate and Forticlient regularly send
information to Fortinet servers (DNS: on
- UDP ports 53, 8888 and
- TCP port 80 (HTTP POST /fgdsvc)

This cloud communication is used for the FortiGuard Web Filter feature (,
FortiGuard AntiSpam feature (
and FortiGuard AntiVirus feature (

The messages are encrypted using XOR "encryption" with a static key.

The protocol messages contain the following types of information:

**Serial number of the Fortinet product installation** (product type + unique ID).
This information allows an attacker who can **passively monitor** internet traffic to:
- learn which Fortinet products and product types an organization uses
  (this is valuable for information gathering, see EquationGroup Fortigate exploits)
- learn which FortiClient installations are part of an organization
- use the FortiClient serial number as a unique identifier to track an individual as
  he/she travels the world

**Full HTTP URLs of users web surfing activity** (Web Filter feature).
This information allows an attacker who can **passively monitor** internet traffic
to spy on users' web surfing activity. In cases where SSL inspection is enabled,
even the URLs of HTTPS-encrypted communication are sent via this protocol,
effectively breaking the confidentiality of SSL/TLS.

**Unspecified email data** (AntiSpam feature).
We do not have any further information on what kind of information is sent by the
AntiSpam feature.

**Unspecified AntiVirus data** (AntiVirus feature).
We do not have any further information on what kind of information is sent by the
AntiVirus feature.

By **intercepting and manipulating** internet traffic an attacker can:
Manipulate the responses for FortiGuard Web Filter, AntiSpam and AntiVirus features.

Proof of concept:
The following Python 3 script decrypts a FortiGuard message (the static XOR key
has been removed from this advisory).

from itertools import cycle

def forti_xor(s1):
    xor_key = **removed**
    message = ''.join(chr(c ^ k) for c, k in zip(s1, cycle(xor_key)))
    return message



In this case the encrypted message contents are:

Another example:

Vulnerable / tested versions:
The following FortiOS versions are affected according to the vendor:
* FortiOS 6.0.6 and below
* FortiClientWindows 6.0.6 and below
* FortiClientMac 6.2.1 and below

The security advisory of the vendor can be found at:

Vendor contact timeline:
2018-05-17: Contacting vendor through, sending advisory with
            public PGP key
2018-05-17: Auto-Response: "Thank you for contacting us regarding your
            inquiry. We have created a PSIRT ticket for this inquiry"
2018-05-17: Response: "Thank you to report us this vulnerability. I created
            an internal incident and I will communicate further with you while
            I'm investigating the impact of this."
2018-05-28: Requesting update, "If we don't get an appropriate response (see my
            initial email) by the end of next week, we will consider disclosing
            the vulnerability without further coordination."
2018-05-28: Auto-Response: "Thank you for contacting us regarding your inquiry.
            We have created a PSIRT ticket for this inquiry"
2018-06-05: Requesting update again, "This is the final attempt to contact you",
            plus reaching out to Fortinet via Twitter, LinkedIn.
2018-06-05: First response after 3 weeks, developers are working on a fix,
            "Please therefore kindly wait for further updates, while we are
            coordinating various stakeholders (including FortiGuard servers
            maintainers) for a fix."
2018-06-06: Requesting conference call.
2018-06 - 2019-11: Multiple conference calls, discussing technical details, agreeing
            on disclosure time
2019-03-28: Fix released in FortiOS 6.2.0
2019-04-01: Fix issued on FortiGuard server side
2019-11-13: Fix released for FortiOS branch 6.0, version 6.0.7
2019-11-25: Public release of security advisory

The vendor provides updated versions for the affected products:
* FortiOS 6.0.7 or 6.2.0
* FortiClientWindows 6.2.0
* FortiClientMac 6.2.2

The security advisory of the vendor can be found at:


Advisory URL:


SEC Consult Vulnerability Lab

SEC Consult
Europe | Asia | North America

About SEC Consult Vulnerability Lab
The SEC Consult Vulnerability Lab is an integrated part of SEC Consult. It
ensures the continued knowledge gain of SEC Consult in the field of network
and application security to stay ahead of the attacker. The SEC Consult
Vulnerability Lab supports high-quality penetration testing and the evaluation
of new offensive and defensive technologies for our customers. Hence our
customers obtain the most current information about vulnerabilities and valid
recommendation about the risk profile of new technologies.

Interested to work with the experts of SEC Consult?
Send us your application

Interested in improving your cyber security with the experts of SEC Consult?
Contact our local offices

Mail: research at sec-consult dot com

EOF Stefan Viehböck / @2019

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