has used Dropbear SSH with a hardcoded backdoor password to maintain persistence within the target network.  has also used VPN tunnels established in legitimate software company infrastructure to gain access to internal networks of that software company's users.(Citation: ESET BlackEnergy Jan 2016)(Citation: ESET Telebots June 2017)
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: has used Dropbear SSH with a hardcoded backdoor password to maintain persistence within the target network.  has also used VPN tunnels established in legitimate software company infrastructure to gain access to internal networks of that software company's users.(Citation: ESET BlackEnergy Jan 2016)(Citation: ESET Telebots June 2017) ### Response: T1133.