UltimateMenu is an open-source YimMenu Lua script — anyone can audit the code on GitHub. That said, no mod menu is risk-free: Rockstar can ban accounts that mod GTA Online. Reduce risk by using a secondary account, playing in invite-only sessions, disabling BattlEye for story/invite use per the guide, and never paying anyone for this free script. Use at your own risk — see the footer disclaimer.