I want to discuss the following scenario: 

I use a cloud provider like Amazon where every instance of the OS is a VM. The hypervisor launches the VMs as needed. So let's assume there are two VMs running, mine and attacker's on the same box at the same time.

**Scenario 1**: The attacker has root access to his VM. But does not have physical access to the box. What attack vectors do I worry about? 
       
- Obviously any vulnerabilities in my VM (OS and services it provides).  
      Let's assume this is out of scope for this discussion

- Vulnerabilities in the hypervisor that lets the attacker intercept all data to and from my VM. 
      Are there known vulnerabilities like this? 

- Any other scenarios like DMA attacks? 

**Scenario 2**: The attacker has physical access to the box. He manages the box and is able to install custom hardware or use the peripherals like USB, HDMI etc? 

 - I know that one can introspect the VM he wants to attack directly as software-based attacks are easier. Let's assume it's out of scope.