(credit: Fortinet)

An unknown threat actor abused a critical vulnerability in Fortinet’s FortiOS SSL-VPN to infect government and government-related organizations with advanced custom-made malware, the company said in an autopsy report on Wednesday.

Tracked as ​​CVE-2022-42475, the vulnerability is a heap-based buffer overflow that allows hackers to remotely execute malicious code. It carries a severity rating of 9.8 out of a possible 10. A maker of network security software, Fortinet fixed the vulnerability in version 7.2.3 released on November 28 but failed to make any mention of the threat in the release notes it published at the time.

Mum’s the word

Fortinet didn’t disclose the vulnerability until December 12, when it warned that the vulnerability was under active exploit against at least one of its customers. The company urged customers to ensure they were running the patched version of the software and to search their networks for signs the vulnerability had been exploited on their networks. FortiOS SSL-VPNs are used mainly in border firewalls, which cordon off sensitive internal networks from the public Internet.