Adversaries may hijack a legitimate user's SSH session to move laterally within an environment. Secure Shell (SSH) is a standard means of remote access on Linux and macOS systems. It allows a user to connect to another system via an encrypted tunnel, commonly authenticating through a password, certificate or the use of an asymmetric encryption key pair.

In order to move laterally from a compromised host, adversaries may take advantage of trust relationships established with other systems via public key authentication in active SSH sessions by hijacking an existing connection to another system. This may occur through compromising the SSH agent itself or by having access to the agent's socket. If an adversary is able to obtain root access, then hijacking SSH sessions is likely trivial.(Citation: Slideshare Abusing SSH)(Citation: SSHjack Blackhat)(Citation: Clockwork SSH Agent Hijacking)(Citation: Breach Post-mortem SSH Hijack)

[SSH Hijacking](https://attack.mitre.org/techniques/T1563/001) differs from use of [SSH](https://attack.mitre.org/techniques/T1021/004) because it hijacks an existing SSH session rather than creating a new session using [Valid Accounts](https://attack.mitre.org/techniques/T1078).
SSH Hijacking
source_name: mitre-attack  url: https://attack.mitre.org/techniques/T1563/001  external_id: T1563.001     source_name: Slideshare Abusing SSH  description: Duarte, H., Morrison, B. (2012). (Mis)trusting and (ab)using ssh. Retrieved January 8, 2018.  url: https://www.slideshare.net/morisson/mistrusting-and-abusing-ssh-13526219     source_name: SSHjack Blackhat  description: Adam Boileau. (2005, August 5). Trust Transience:  Post Intrusion SSH Hijacking. Retrieved December 19, 2017.  url: https://www.blackhat.com/presentations/bh-usa-05/bh-us-05-boileau.pdf     source_name: Clockwork SSH Agent Hijacking  description: Beuchler, B. (2012, September 28). SSH Agent Hijacking. Retrieved December 20, 2017.  url: https://www.clockwork.com/news/2012/09/28/602/ssh_agent_hijacking     source_name: Breach Post-mortem SSH Hijack  description: Hodgson, M. (2019, May 8). Post-mortem and remediations for Apr 11 security incident. Retrieved February 17, 2020.  url: https://matrix.org/blog/2019/05/08/post-mortem-and-remediations-for-apr-11-security-incident     