Email addresses could also be enumerated via more active means (i.e. [Active Scanning](https://attack.mitre.org/techniques/T1595)), such as probing and analyzing responses from authentication services that may reveal valid usernames in a system.(Citation: GrimBlog UsernameEnum)
Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request. ### Instruction: List the MITRE techniques contained in the text. ### Input: Email addresses could also be enumerated via more active means (i.e. [Active Scanning](https://attack.mitre.org/techniques/T1595)), such as probing and analyzing responses from authentication services that may reveal valid usernames in a system.(Citation: GrimBlog UsernameEnum) ### Response: T1589.002.