Query: SIEM correlation: persistence activity consistent with SSH Authorized Keys
Matching passage: T1098.004 SSH Authorized Keys. Tactics: persistence, privilege escalation. Description: Adversaries may modify the SSH <code>authorized_keys</code> file to maintain persistence on a victim host. Linux distributions, macOS, and ESXi hypervisors commonly use key-based authentication to secure the authentication process of SSH sessions for remote management. The <code>authorized_keys</code> file in SSH specifies the SSH keys that can be used for logging into the user account for which the file is configured. This file is usually found in the user's home directory under <code>&lt;user-home&gt;/.ssh/authorized_keys</code> (or, on ESXi, `/etc/ssh/keys-<username>/authorized_keys`).(Citation: SSH Authorized Keys) Users may edit the system’s SSH config file to modify the directives `PubkeyAuthentication` and `RSAAuthentication` to the value `yes` to ensure public key and RSA authentication are enabled, as well as modify the directive `PermitRootLogin` to the value `yes` to enable root authentication via SSH.(Citation: Broadcom ESXi SSH) The SSH config file is usually located under <code>/etc/ssh/sshd_config</code>. Adversaries may modify SSH <code>authorized_keys</code> files directly with scripts or shell commands to add their own adversary-supplied public keys. In cloud environments, adversaries may be able to modify the SSH authorized_keys file of a particular virtual machine via the command line interface or rest API. For example, by using the Google Cloud CLI’s “add-metadata” command an adversary may add SSH keys to a user account.(Citation: Google Cloud Add Metadata)(Citation: Google Cloud Privilege Escalation) Similarly, in Azure, an adversary may update the authorized_keys file of a virtual machine via a PATCH request to the API.(Citation: Azure Update Virtual Machines) This ensures that an adversary possessing the corresponding private key may log in as an existing user via SSH.(Citation: Venafi SSH Key Abuse)(Citation: Cybereason Linux Exim Worm) It may also lead to privilege escalation where the virtual machine or instance has distinct permissions fr
Near-miss passage: T1098.003 Additional Cloud Roles. Tactics: persistence, privilege escalation. Description: An adversary may add additional roles or permissions to an adversary-controlled cloud account to maintain persistent access to a tenant. For example, adversaries may update IAM policies in cloud-based environments or add a new global administrator in Office 365 environments.(Citation: AWS IAM Policies and Permissions)(Citation: Google Cloud IAM Policies)(Citation: Microsoft Support O365 Add Another Admin, October 2019)(Citation: Microsoft O365 Admin Roles) With sufficient permissions, a compromised account can gain almost unlimited access to data and settings (including the ability to reset the passwords of other admins).(Citation: Expel AWS Attacker) (Citation: Microsoft O365 Admin Roles) This account modification may immediately follow [Create Account](https://attack.mitre.org/techniques/T1136) or other malicious account activity. Adversaries may also modify existing [Valid Accounts](https://attack.mitre.org/techniques/T1078) that they have compromised. This could lead to privilege escalation, particularly if the roles added allow for lateral movement to additional accounts. For example, in AWS environments, an adversary with appropriate permissions may be able to use the <code>CreatePolicyVersion</code> API to define a new version of an IAM policy or the <code>AttachUserPolicy</code> API to attach an IAM policy with additional or distinct permissions to a compromised user account.(Citation: Rhino Security Labs AWS Privilege Escalation) In some cases, adversaries may add roles to adversary-controlled accounts outside the victim cloud tenant. This allows these external accounts to perform actions inside the victim tenant without requiring the adversary to [Create Account](https://attack.mitre.org/techniques/T1136) or modify a victim-owned account.(Citation: Invictus IR DangerDev 2024)