Alert - Compromise and persistent access of Fortinet FortiOS products (CVE-2022-42475, CVE-2023-27997, CVE-2024-21762)

Alert

Number: AL25-005
Date: April 14, 2025

Audience

This Alert is intended for IT professionals and managers of notified organizations.

Purpose

An Alert is used to raise awareness of a recently identified cyber threat Cyber threatA threat actor, using the internet, who takes advantage of a known vulnerability in a product for the purposes of exploiting a network and the information the network carries. that may impact cyber information assets, and to provide additional detection DetectionThe monitoring and analyzing of system events in order to identify unauthorized attempts to access system resources. and mitigation advice to recipients. The Canadian Centre for Cyber Security Cyber securityThe protection of digital information, as well as the integrity of the infrastructure housing and transmitting digital information. More specifically, cyber security includes the body of technologies, processes, practices and response and mitigation measures designed to protect networks, computers, programs and data from attack, damage or unauthorized access so as to ensure confidentiality, integrity and availability. ("Cyber Centre") is also available to provide additional assistance regarding the content of this Alert to recipients as requested.

Details

On April 10, 2025, Fortinet released a PSIRT blog^{Footnote 1} describing widespread exploitation of vulnerabilities in Fortinet FortiOS products going back to 2023. Threat actors have compromised vulnerable devices and maintained persistence even after patches were applied, potentially accessing sensitive files including credentials and key material.

CVE-2022-42475^{Footnote 2}, CVE-2023-27997^{Footnote 3} and CVE-2024-21762^{Footnote 4} are all previous CVEs that have been exploited through this malicious activity. CCCS had published respective advisories for each one of them.

The following Fortinet products are affected by this vulnerability VulnerabilityA flaw or weakness in the design or implementation of an information system or its environment that could be exploited to adversely affect an organization's assets or operations. :

• FortiOS – versions 7.4, 7.2, 7.0 and 6.4

Note that customers who have not enabled SSL-VPN VPNSee virtual private network. are not impacted by this vulnerability.

Suggested Actions

The Cyber Centre strongly recommends that organizations patch their FortiOS to the following versions:

• FortiOS – versions 7.6.2, 7.4.7, 7.2.11 & 7.0.17 or 6.4.16

It is imperative for organizations to identify and prioritize the patching of vulnerable systems promptly, using the following links:

• Fortinet PSIRT Advisory (FG-IR-22-398)
• Fortinet PSIRT Advisory (FG-IR-23-097)
• Fortinet PSIRT Advisory (FG-IR-24-015)

Recommendations:

• Reset credentials: Assume compromise^{Footnote 5} and reset all credentials associated with SSL-VPN functionality, affected devices, user accounts, LDAP bind credentials, and pre-shared keys.
• Apply updates: Apply the latest updates to remove the malicious file and enable automatic updates for OS and AV/IPS.
• Review and monitor: Review the vendor advisory ^{Footnote 1}. Review logging for unauthorized SSL VPN access, including configurations for any unauthorized changes, and review network logging for known indicators of compromise.
• Disable or limit access: Disable SSL-VPN functionality if not required, limit access to trusted IP ranges, and disable administrative access to any external (Internet-facing) interface.

The Cyber Centre recommends that organizations:

• Assess the installations of the affected Fortinet products and monitor for signs of exploitation.
• Apply software patches to affected Fortinet products as soon as they become available.

In addition, the Cyber Centre strongly recommends that organizations review and implement the Cyber Centre's Top 10 IT Security Actions ^{Footnote 6} with an emphasis on the following strategies:

• Consolidate, monitor, and defend Internet gateways.
• Patch operating systems and applications.
• Isolate web-facing applications.

If activity matching the content of this alert is discovered, recipients are encouraged to report via the My Cyber Portal, or email contact@cyber.gc.ca.

Partner Reporting

• NCSC NZ – CVEs affecting Fortinet FortiOS products
• CERT NZ – Malicious activity due to previously exploited vulnerabilities in Fortinet FortiOS products
• CISA – Fortinet releases advisory on new post-exploitation technique for known vulnerabilities

About The Cyber Centre

The Canadian Centre for Cyber Security (Cyber Centre) operates as part of the Communications Security Establishment. We are Canada's national authority on cyber security, and we lead the government's response to cyber security events. As Canada's national computer security incident response team, the Cyber Centre works in close collaboration with government departments, critical infrastructure Critical infrastructureProcesses, systems, facilities, technologies, networks, assets, and services essential to the health, safety, security, or economic well-being of Canadians and the effective functioning of government. Critical infrastructure can be stand-alone or interconnected and interdependent within and across provinces, territories, and national borders. Disruptions of critical infrastructure could result in catastrophic loss of life, adverse economic effects, and significant harm to public confidence. , Canadian businesses, and international partners to prepare for, respond to, mitigate, and recover from cyber events. We do this by providing authoritative advice and support and coordinating information sharing and incident response. The Cyber Centre is outward-facing, welcoming partnerships that help build a stronger, more resilient cyber space in Canada.

References