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             AUSCERT External Security Bulletin Redistribution

           FortiOS SSL VPN 2FA bypass by changing username case
                               16 July 2020


        AusCERT Security Bulletin Summary

Product:           FortiOS
Publisher:         Fortiguard
Operating System:  Network Appliance
Impact/Access:     Reduced Security -- Existing Account
Resolution:        Patch/Upgrade
CVE Names:         CVE-2020-12812  

Original Bulletin: 

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FortiOS SSL VPN 2FA bypass by changing username case

IR Number : FG-IR-19-283

Date      : Jul 13, 2020

Risk      : 3/5

Impact    : Operational Risk, Improper Authentication

CVE ID    : CVE-2020-12812

CVE ID    : CVE-2020-12812

CVE ID    : CVE-2020-12812


An improper authentication vulnerability in SSL VPN in FortiOS may result in a
user being able to log in successfully without being prompted for the second
factor of authentication (FortiToken) if they changed the case of their

This happens when two-factor authentication is enabled in the "user local"
setting, and that user authentication type is set to a remote authentication
method (eg: ldap).

The issue exists because of inconsistent case sensitive matching among the
local and remote authentication.

A new CLI attribute called "username-case-sensitivity" was added in "user
local" CLI settings, and is now available when remote and two-factor
authentication are both enabled:

config user local
edit [name]
set type ldap /* ldap as remote authentication */
set two-factor fortitoken /* fortitoken as 2FA auth method */
set username-case-sensitivity enable*|disable /* newly added, set to 'enable'
by default */

username-case-sensitivity is enabled by default; this is consistent with the
default behavior on previous versions (local and remote username case must
match). To avoid the second factor of authentication bypass issue,
administrators must manually disable username-case-sensitivity.


Operational Risk, Improper Authentication

Affected Products

FortiOS 6.4.0, 6.2.0 to 6.2.3, 6.0.9 and below


Upgrade to the following FortiOS version:

6.4.1 or later

6.2.4 or later

6.0.10 or later


  o https://kb.fortinet.com/kb/documentLink.do?externalID=FD37033

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