Hi, where did you download the Windows installer from? Odoo installers should always be downloaded from the official odoo website on odoo.com/download.

Further, what makes you think you were attacked by a ransomware that was related to this?

It's definitely not "common" nor expected, the official Odoo installers do not contain any malware. There is however a false positive detection currently active where Microsoft Defender/Smartscreen will report the official Odoo installers as containing malware (Trojan:Win32/Wacatac.H!ml or Trojan:Win32/AgentTesla!ml, and perhaps others). You can find more information about it on this other post, including the recommendation to upload your installer on VirusTotal in order to have it tested for malware by dozens of anti-malware scanners.