SEC Consult Vulnerability Lab Security Advisory < 20191125-0 >
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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
homepage: https://www.fortinet.com
found: 2018-05-16
by: Stefan Viehböck (Office Vienna)
SEC Consult Vulnerability Lab
An integrated part of SEC Consult
Europe | Asia | North America
https://www.sec-consult.com
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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."
Source: https://www.fortinet.com/corporate/about-us/about-us.html
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: guard.fortinet.com) on
- UDP ports 53, 8888 and
- TCP port 80 (HTTP POST /fgdsvc)
This cloud communication is used for the FortiGuard Web Filter feature (https://fortiguard.com/webfilter),
FortiGuard AntiSpam feature (https://fortiguard.com/updates/antispam)
and FortiGuard AntiVirus feature (https://fortiguard.com/updates/antivirus).
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).
```python
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
r1=bytes.fromhex('6968766f606e776c2d2d21262138475c5b5a475b545e475c6b6a776b646e776c6b6a772b646e776c6b6a776b646e776c6b6a776bbadf04036b6a776c616a846f')
print(repr(forti_xor(r1)))
```
In this case the encrypted message contents are:
'\x02\x02\x01\x04\x04\x00\x00\x00FGVMEV0000000000\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00@\x00\x00\x00\x00\x00\x00...'
Another example:
'\x02\x01\x02\x04úI\x03\x00FG100D3G00000000\x00\x00\...x00\x00+https://v10.vortex-win.data.microsoft.com/\x00'
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:
https://fortiguard.com/psirt/FG-IR-18-100
Vendor contact timeline:
------------------------
2018-05-17: Contacting vendor through psirt@xxxxxxxxxxxx, 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
Solution:
---------
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: https://fortiguard.com/psirt/FG-IR-18-100
Workaround:
-----------
None
Advisory URL:
-------------
https://www.sec-consult.com/en/vulnerability-lab/advisories/index.html
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
SEC Consult Vulnerability Lab
SEC Consult
Europe | Asia | North America
About SEC Consult Vulnerability Lab
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EOF Stefan Viehböck / @2019
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