Explanation
A bastion is a system that is exposed to the public Internet to perform a specific function, but it is highly restricted and secured to just that function. Any nonessential services and access are removed from the bastion so that security countermeasures and monitoring can be focused just on the bastion's specific duties. A honeypot is a system designed to look like a production system to entice attackers, but it does not contain any real data. It is used for learning about types of attacks and enabling countermeasures for them. A firewall is used within a network to limit access between IP addresses and ports. A proxy server provides additional security to and rulesets for network traffic that is allowed to pass through it to a service destination.

Security misconfigurations occur when applications and systems are not properly configured or maintained in a secure manner. This can be due to a shortcoming in security baselines or configurations, unauthorized changes to system configurations, or a failure to patch and upgrade systems as the vendor releases security patches. Insecure direct object references occur when code references aspects of the infrastructure, especially internal or private systems, and an attacker can use that knowledge to glean more information about the infrastructure. Unvalidated redirects and forwards occur when an application has functions to forward users to other sites, and these functions are not properly secured to validate the data and redirect requests, allowing spoofing for malware or phishing attacks. Sensitive data exposure occurs when an application does not use sufficient encryption and other security controls to protect sensitive application data.

Reversibility is the cloud concept involving the ability for a cloud customer to remove all of its data and IT assets from a cloud provider. Also, processes and agreements would be in place with the cloud provider that ensure all removals have been completed fully within the agreed upon timeframe. Portability refers to the ability to easily move between different cloud providers and not be locked into a specific one.
Removability and extraction are both provided as terms similar to reversibility, but neither is the official term or concept.