What secures the Omni network?

Could you elaborate on the security measures that underpin the Omni network? I'm particularly interested in understanding how it ensures the integrity and safety of transactions. Does it rely solely on the Bitcoin blockchain, or does it have additional layers of security? Are there any known vulnerabilities or potential risks that investors should be aware of? Your insights would be invaluable in helping me make an informed decision about participating in the Omni ecosystem.