Critical FortiOS and FortiProxy Vulnerability Likely Exploited

Jun 13, 2023Ravie LakshmananNetwork Security / Vulnerability

Fortinet on Monday disclosed that a newly patched critical flaw impacting FortiOS and FortiProxy may have been “exploited in a limited number of cases” in attacks targeting government, manufacturing, and critical infrastructure sectors.

The vulnerability, tracked as CVE-2023-27997 (CVSS score: 9.2), concerns a heap-based buffer overflow vulnerability in FortiOS and FortiProxy SSL-VPN that could allow a remote attacker to execute arbitrary code or commands via specifically crafted requests.

LEXFO security researchers Charles Fol and Dany Bach have been credited with discovering and reporting the flaw. It was addressed by Fortinet on June 9, 2023 in the following versions –

• FortiOS-6K7K version 7.0.12 or above
• FortiOS-6K7K version 6.4.13 or above
• FortiOS-6K7K version 6.2.15 or above
• FortiOS-6K7K version 6.0.17 or above
• FortiProxy version 7.2.4 or above
• FortiProxy version 7.0.10 or above
• FortiProxy version 2.0.13 or above
• FortiOS version 7.4.0 or above
• FortiOS version 7.2.5 or above
• FortiOS version 7.0.12 or above
• FortiOS version 6.4.13 or above
• FortiOS version 6.2.14 or above, and
• FortiOS version 6.0.17 or above

The company, in an independent disclosure, said the issue was simultaneously discovered during a code audit that was prudently initiated following the active exploitation of a similar flaw in the SSL-VPN product (CVE-2022-42475, CVSS score: 9.3) in December 2022.

Fortinet further said it is not attributing the exploitation events at this stage to a Chinese state-sponsored actor codenamed Volt Typhoon, which was disclosed by Microsoft last month as leveraging an unknown zero-day flaw in internet-facing Fortinet FortiGuard devices to gain initial access to target environments.

It, however, noted it “expects all threat actors, including those behind the Volt Typhoon campaign, to continue to exploit unpatched vulnerabilities in widely used software and devices.”

In light of active in-the-wild abuse, the company is recommending that customers take immediate action to update to the latest firmware version to avert potential risks.

“Fortinet continues to monitor the situation and has been proactively communicating to customers, strongly urging them to immediately follow the guidance provided to mitigate the vulnerability using either the provided workarounds or by upgrading,” the company told The Hacker News.