IPS Engine evasion using custom TCP flags Fortinet PSIRT Advisories Fortinet PSIRT Contact: Website: https://fortiguard.fortinet.com/faq/psirt-contact FG-IR-23-090 Final 1 1 2023-10-10T00:00:00 Current version 2023-10-10T00:00:00 2023-10-10T00:00:00 An interpretation conflict vulnerability [CWE-436] in FortiOS IPS Engine may allow an unauthenticated remote attacker to evade NGFW policies or IPS Engine protection via crafted TCP packets. None Improper access control FortiOS 7.4 all versions are not affectedFortiOS version 7.2.0 through 7.2.4FortiOS version 7.0.2 through 7.0.11FortiOS version 6.4.0 through 6.4.12At leastIPS Engine version 7.321IPS Engine version 7.166IPS Engine version 6.158 IPS Engine manual download is not needed unless device is offline and cannot download IPS Engine update automatically.Fixed in IPS Engine version 6.0159 and later.FortiOS 6.4.13 and later contains IPS engine 6.0160 as the default IPS Engine.IPS Engine 6.0162 is downloadable from FortiGuard by FortiGate units with a valid subscription running FortiOS 6.4.x.Fixed in IPS Engine version 7.0166 and later.FortiOS 7.0.12 and later contains IPS engine 7.0167 as the default IPS Engine.Fixed in IPS Engine version 7.0313 and later.FortiOS 7.2.5 and later contains IPS engine 7.0314 as the default IPS Engine.IPS Engine 7.0322 is downloadable from FortiGuard by FortiGate units with a valid subscription running FortiOS 7.2.x.FortiOS 7.4.0 and later contains IPS engine 7.0493 as the default IPS Engine. Fortinet is pleased to thank DISO and Cybersecurity Lab of the University of Udine to report this vulnerability. FortiOS 7.2.4 FortiOS 7.2.3 FortiOS 7.2.2 FortiOS 7.2.1 FortiOS 7.2.0 FortiOS 7.0.11 FortiOS 7.0.10 FortiOS 7.0.9 FortiOS 7.0.8 FortiOS 7.0.7 FortiOS 7.0.6 FortiOS 7.0.5 FortiOS 7.0.4 FortiOS 7.0.3 FortiOS 7.0.2 FortiOS 6.4.12 FortiOS 6.4.11 FortiOS 6.4.10 FortiOS 6.4.9 FortiOS 6.4.8 FortiOS 6.4.7 FortiOS 6.4.6 FortiOS 6.4.5 FortiOS 6.4.4 FortiOS 6.4.3 FortiOS 6.4.2 FortiOS 6.4.1 FortiOS 6.4.0 IPS Engine 7.321 IPS Engine 7.166 IPS Engine 6.158 CVE-2023-40718 FortiOS-7.2.4 FortiOS-7.2.3 FortiOS-7.2.2 FortiOS-7.2.1 FortiOS-7.2.0 FortiOS-7.0.11 FortiOS-7.0.10 FortiOS-7.0.9 FortiOS-7.0.8 FortiOS-7.0.7 FortiOS-7.0.6 FortiOS-7.0.5 FortiOS-7.0.4 FortiOS-7.0.3 FortiOS-7.0.2 FortiOS-6.4.12 FortiOS-6.4.11 FortiOS-6.4.10 FortiOS-6.4.9 FortiOS-6.4.8 FortiOS-6.4.7 FortiOS-6.4.6 FortiOS-6.4.5 FortiOS-6.4.4 FortiOS-6.4.3 FortiOS-6.4.2 FortiOS-6.4.1 FortiOS-6.4.0 IPS Engine-7.321 IPS Engine-7.166 IPS Engine-6.158 6.7 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N/E:F/RL:O/RC:R https://fortiguard.fortinet.com/psirt/FG-IR-23-090 IPS Engine evasion using custom TCP flags Reference>