Adversaries may modify the SSH <code>authorized_keys</code> file to maintain persistence on a victim host. Linux distributions and macOS 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><user-home>/.ssh/authorized_keys</code>.(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. 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. 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)
View in MITRE ATT&CK®| Capability ID | Capability Description | Mapping Type | ATT&CK ID | ATT&CK Name |
|---|---|---|---|---|
| AC-3 | Access Enforcement | Protects | T1098.004 | SSH Authorized Keys |
| CM-2 | Baseline Configuration | Protects | T1098.004 | SSH Authorized Keys |
| CM-6 | Configuration Settings | Protects | T1098.004 | SSH Authorized Keys |
| CM-7 | Least Functionality | Protects | T1098.004 | SSH Authorized Keys |
| CM-8 | System Component Inventory | Protects | T1098.004 | SSH Authorized Keys |
| RA-5 | Vulnerability Monitoring and Scanning | Protects | T1098.004 | SSH Authorized Keys |
| SC-12 | Cryptographic Key Establishment and Management | Protects | T1098.004 | SSH Authorized Keys |
| SI-3 | Malicious Code Protection | Protects | T1098.004 | SSH Authorized Keys |
| SI-4 | System Monitoring | Protects | T1098.004 | SSH Authorized Keys |
| attribute.integrity.variety.Modify privileges | Modified privileges or permissions | related-to | T1098.004 | Account Manipulation: SSH Authorized Keys |
| amazon_guardduty | Amazon GuardDuty | technique_scores | T1098.004 | SSH Authorized Keys |