CVE-2022-42475: Fortinet Patches Zero Day in FortiOS SSL VPNs
Fortinet has patched a zero day buffer overflow in FortiOS that could lead to remote code execution. There has been a report of active exploitation and organizations should patch urgently.
Update January 12: The Analysis section has been updated based on a technical write up from Fortinet PSIRT.
On December 9 Olympe Cyberdefense published a brief summary of a vulnerability affecting several versions of Fortinet FortiOS used in its FortiGate secure socket layer virtual private network (SSL VPN) and firewall products.
Fortinet followed up on December 12 with an advisory which elaborated that the vulnerability has been observed under exploitation. Fortinet’s language implies this exploitation was limited in scope, specifying “an instance.” It is unclear whether Fortinet observed this exploitation directly or if it was reported to them by the researchers.
CVE-2022-42475 is a heap-based buffer overflow in several versions of ForiOS that received a CVSSv3 score of 9.3. A remote, unauthenticated attacker could exploit this vulnerability with a specially crafted request and gain code execution. The blog from Olympe Cyberdefense goes further, stating attackers could gain “full control.”
On January 11, Fortinet’s product security incident response team published additional information about the attacks targeting CVE-2022-42475, including indicators of compromise. According to its investigation, the attacks were complex and highly targeted at “governmental or government-related targets.”
Threat actors have been leveraging vulnerabilities in Fortinet SSL VPNs in attacks for several years to the extent that the Federal Bureau of Investigation and Cybersecurity and Infrastructure Security Agency issued a dedicated advisory to these flaws and their exploitation in 2021. Given that this vulnerability has already been exploited, organizations should patch CVE-2022-42475 immediately.
According to Fortinet’s advisory, the following are the affected versions of FortiOS and the relevant fixed versions:
|Affected Version||Fixed Version|
|FortiOS version 7.2.0 through 7.2.2||FortiOS version 7.23 or above|
|FortiOS version 7.0.0 through 7.0.8||FortiOS version 7.0.9 or above|
|FortiOS version 6.4.0 through 6.4.10||FortiOS version 6.4.11 or above|
|FortiOS version 6.2.0 through 6.2.11||FortiOS version 6.2.12 or above|
|FortiOS version 6.0.0 through 6.0.15||FortiOS version 6.0.16 or above (Added 12/13/2022)|
|FortiOS version 5.6.0 through 5.6.14||None listed (Added 12/13/2022)|
|FortiOS version 5.4.0 through 5.4.13||None listed (Added 12/13/2022)|
|FortiOS version 5.2.0 through 5.2.15||None listed (Added 12/13/2022)|
|FortiOS version 5.0.0 through 5.0.14||None listed (Added 12/13/2022)|
|FortiOS-6K7K version 7.0.0 through 7.0.7||FortiOS-6K7K version 7.0.8 or above|
|FortiOS-6K7K version 6.4.0 through 6.4.9||FortiOS-6K7K version 6.4.10 or above|
|FortiOS-6K7K version 6.2.0 through 6.2.11||FortiOS-6K7K version 6.2.12 or above|
|FortiOS-6K7K version 6.0.0 through 6.0.14||FortiOS-6K7K version 6.0.15 or above|
|FortiProxy version 7.2.0 through 7.2.1||FortiProxy version 7.2.2 or above (Added 12/22/2022)|
|FortiProxy version 7.0.0 through 7.0.7||FortiProxy version 7.0.8 or above (Added 12/22/2022)|
|FortiProxy version 2.0.0 through 2.0.11||None listed (Added 12/22/2022)|
|FortiProxy version 1.2.0 through 1.2.13||None listed (Added 12/22/2022)|
|FortiProxy version 1.1.0 through 1.1.6||None listed (Added 12/22/2022)|
|FortiProxy version 1.0.0 through 1.0.7||None listed (Added 12/22/2022)|
Fortinet’s advisory also includes indicators of compromise (IoC) for the observed exploitation of this flaw. The advisory from Fortinet recommends reviewing systems for these IoCs as does the blog from Olympe Cyberdefense.
Identifying affected systems
A list of Tenable plugins to identify this vulnerability can be found here. This link uses a search filter to ensure that all matching plugin coverage will appear as it is released. In addition, plugin ID 73522 can be used to identify Fortinet devices in your network. A Tenable audit with best practices for Fortigate FortiOS is also available here which can help with security hardening.
Get more information
Update December 22: Fortinet has added several versions of FortiProxy to the list of products affected by this vulnerability. The table in the Solution section has been updated accordingly.
Update December 13: Fortinet has disclosed more versions of FortiOS affected by this vulnerability. The table in the Solution section has been updated accordingly.
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