SSH

Behavioral Detection of Remote SSH Logins Followed by Post-Login Execution

Disable or Remove Feature or Program: Disable or remove unnecessary and potentially vulnerable software, features, or services to reduce the attack surface and prevent abuse by adversaries. This involves identifying software or features that are no longer needed or that could be exploited and ensuring they are either removed or properly disabled. This mitigation can be implemented through the following measures:

Remove Legacy Software:

• Use Case: Disable or remove older versions of software that no longer receive updates or security patches (e.g., legacy Java, Adobe Flash).
• Implementation: A company removes Flash Player from all employee systems after it has reached its end-of-life date.

Disable Unused Features:

• Use Case: Turn off unnecessary operating system features like SMBv1, Telnet, or RDP if they are not required.
• Implementation: Disable SMBv1 in a Windows environment to mitigate vulnerabilities like EternalBlue.

Control Applications Installed by Users:

• Use Case: Prevent users from installing unauthorized software via group policies or other management tools.
• Implementation: Block user installations of unauthorized file-sharing applications (e.g., BitTorrent clients) in an enterprise environment.

Remove Unnecessary Services:

• Use Case: Identify and disable unnecessary default services running on endpoints, servers, or network devices.
• Implementation: Disable unused administrative shares (e.g., C$, ADMIN$) on workstations.

Restrict Add-ons and Plugins:

• Use Case: Remove or disable browser plugins and add-ons that are not needed for business purposes.
• Implementation: Disable Java and ActiveX plugins in web browsers to prevent drive-by attacks.

Multi-factor Authentication: Multi-Factor Authentication (MFA) enhances security by requiring users to provide at least two forms of verification to prove their identity before granting access. These factors typically include:

• Something you know: Passwords, PINs.
• Something you have: Physical tokens, smartphone authenticator apps.
• Something you are: Biometric data such as fingerprints, facial recognition, or retinal scans.

Implementing MFA across all critical systems and services ensures robust protection against account takeover and unauthorized access. This mitigation can be implemented through the following measures:

Identity and Access Management (IAM):

• Use IAM solutions like Azure Active Directory, Okta, or AWS IAM to enforce MFA policies for all user logins, especially for privileged roles.
• Enable conditional access policies to enforce MFA for risky sign-ins (e.g., unfamiliar devices, geolocations).
• Enable Conditional Access policies to only allow logins from trusted devices, such as those enrolled in Intune or joined via Hybrid/Entra.

Authentication Tools and Methods:

• Use authenticator applications such as Google Authenticator, Microsoft Authenticator, or Authy for time-based one-time passwords (TOTP).
• Deploy hardware-based tokens like YubiKey, RSA SecurID, or smart cards for additional security.
• Enforce biometric authentication for compatible devices and applications.

Secure Legacy Systems:

• Integrate MFA solutions with older systems using third-party tools like Duo Security or Thales SafeNet.
• Enable RADIUS/NPS servers to facilitate MFA for VPNs, RDP, and other network logins.

Monitoring and Alerting:

• Use SIEM tools to monitor failed MFA attempts, login anomalies, or brute-force attempts against MFA systems.
• Implement alerts for suspicious MFA activities, such as repeated failed codes or new device registrations.

Training and Policy Enforcement:

• Educate employees on the importance of MFA and secure authenticator usage.
• Enforce policies that require MFA on all critical systems, especially for remote access, privileged accounts, and cloud applications.

User Account Management: User Account Management involves implementing and enforcing policies for the lifecycle of user accounts, including creation, modification, and deactivation. Proper account management reduces the attack surface by limiting unauthorized access, managing account privileges, and ensuring accounts are used according to organizational policies. This mitigation can be implemented through the following measures:

Enforcing the Principle of Least Privilege

• Implementation: Assign users only the minimum permissions required to perform their job functions. Regularly audit accounts to ensure no excess permissions are granted.
• Use Case: Reduces the risk of privilege escalation by ensuring accounts cannot perform unauthorized actions.

Implementing Strong Password Policies

• Implementation: Enforce password complexity requirements (e.g., length, character types). Require password expiration every 90 days and disallow password reuse.
• Use Case: Prevents adversaries from gaining unauthorized access through password guessing or brute force attacks.

Managing Dormant and Orphaned Accounts

• Implementation: Implement automated workflows to disable accounts after a set period of inactivity (e.g., 30 days). Remove orphaned accounts (e.g., accounts without an assigned owner) during regular account audits.
• Use Case: Eliminates dormant accounts that could be exploited by attackers.

Account Lockout Policies

• Implementation: Configure account lockout thresholds (e.g., lock accounts after five failed login attempts). Set lockout durations to a minimum of 15 minutes.
• Use Case: Mitigates automated attack techniques that rely on repeated login attempts.

Multi-Factor Authentication (MFA) for High-Risk Accounts

• Implementation: Require MFA for all administrative accounts and high-risk users. Use MFA mechanisms like hardware tokens, authenticator apps, or biometrics.
• Use Case: Prevents unauthorized access, even if credentials are stolen.

Restricting Interactive Logins

• Implementation: Restrict interactive logins for privileged accounts to specific secure systems or management consoles. Use group policies to enforce logon restrictions.
• Use Case: Protects sensitive accounts from misuse or exploitation.

Tools for Implementation

Built-in Tools:

• Microsoft Active Directory (AD): Centralized account management and RBAC enforcement.
• Group Policy Object (GPO): Enforce password policies, logon restrictions, and account lockout policies.

Identity and Access Management (IAM) Tools:

• Okta: Centralized user provisioning, MFA, and SSO integration.
• Microsoft Azure Active Directory: Provides advanced account lifecycle management, role-based access, and conditional access policies.

Privileged Account Management (PAM):

• CyberArk, BeyondTrust, Thycotic: Manage and monitor privileged account usage, enforce session recording, and JIT access.