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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  
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  
  
=======================================================================  
  
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@fortinet.com, 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