Defensive Strategies: TA0001

Defensive Strategies for TA0001 - Initial Access

The Initial Access (TA0001) phase involves attackers gaining entry into a target environment, often through phishing, exploiting vulnerabilities, abusing remote services, or using stolen credentials. In Azure environments, it’s critical to block unauthorized access early through secure configurations, identity protection, and attack detection. Below are defensive strategies mapped to the techniques and sub-techniques of TA0001.

1. Secure Public-Facing Applications and Services

Mitigates: T1190 - Exploit Public-Facing Application

• Action: Identify and patch vulnerabilities in public-facing Azure services and web apps.

• Azure Solution:

  • Use Azure Web Application Firewall (WAF) to block attacks targeting Azure-hosted applications.

  • Enable Azure Defender for App Service to detect vulnerabilities and monitor for suspicious activity.

  • Implement Azure Security Center recommendations to harden configurations.

2. Enforce Multi-Factor Authentication (MFA)

Mitigates: T1078 - Valid Accounts (Cloud Accounts)

• Action: Ensure MFA is enforced for all accounts, especially privileged ones.

• Azure Solution:

  • Use Conditional Access Policies to require MFA for user logins.

  • Apply Azure AD Identity Protection to detect and block risky sign-ins.

  • Monitor token re-use to prevent attackers from abusing compromised tokens for initial access.

3. Harden Remote Services

Mitigates: T1133 - External Remote Services

• Action: Restrict access to RDP, SSH, and Azure Bastion services.

• Azure Solution:

  • Use Just-in-Time (JIT) VM access to limit remote access windows.

  • Monitor Azure Bastion logs to detect suspicious activity.

  • Apply NSG (Network Security Group) rules to restrict access from unauthorized IPs.

4. Detect and Mitigate Phishing Attempts

Mitigates: T1566 - Phishing (Spearphishing Link, Spearphishing Attachment)

• Action: Block phishing emails and prevent OAuth consent phishing.

• Azure Solution:

  • Use Microsoft Defender for Office 365 to block malicious emails and attachments.

  • Monitor for unusual OAuth consent requests with Azure AD Identity Protection.

  • Train users to recognize phishing attempts and report suspicious emails.

5. Monitor OAuth and Consent Grants to Applications

Mitigates: T1199 - Trusted Relationship

• Action: Prevent attackers from abusing application consents to gain access.

• Azure Solution:

  • Use Azure AD Conditional Access Policies to limit which apps can access sensitive resources.

  • Enable alerts in Azure Sentinel for new OAuth permissions being granted.

  • Regularly review third-party app permissions to detect unauthorized grants.

6. Regularly Rotate and Monitor Credentials

Mitigates: T1078 - Valid Accounts (Default Accounts)

• Action: Rotate service principal keys and API tokens regularly to limit abuse.

• Azure Solution:

  • Use Azure Key Vault to store and rotate secrets.

  • Monitor for new keys being added to service principals with Azure Security Center.

  • Disable default or unused accounts in VMs and services to reduce attack surface.

7. Apply Conditional Access Policies for Trusted Devices and Networks

Mitigates: T1199 - Trusted Relationship

• Action: Limit access to Azure resources from only trusted devices and IP addresses.

• Azure Solution:

  • Configure Conditional Access Policies to restrict access based on device compliance.

  • Use Azure Identity Protection to detect and block suspicious sign-ins from unknown devices.

  • Monitor for tenant-to-tenant attacks, especially in multi-tenant environments.

8. Secure DevOps Pipelines from Supply Chain Attacks

Mitigates: T1195 - Supply Chain Compromise (Software Dependencies and Tools)

• Action: Harden DevOps tools and scan for vulnerabilities in pipelines.

• Azure Solution:

  • Use Azure DevOps Security Scanning to detect vulnerable libraries in CI/CD pipelines.

  • Monitor Azure pipelines for unauthorized changes to configurations and jobs.

  • Store build secrets securely in Azure Key Vault.

9. Block Legacy Authentication Protocols

Mitigates: T1078.002 - Domain Accounts

• Action: Disable legacy authentication protocols that don’t support MFA (e.g., POP, IMAP).

• Azure Solution:

  • Use Azure Security Center to detect and disable legacy protocols.

  • Enforce modern authentication via Conditional Access Policies.

  • Monitor for logins using basic authentication protocols and block them.

10. Automate Detection and Response with Azure Sentinel

Mitigates: T1133 - External Remote Services, T1078 - Valid Accounts

• Action: Use Azure Sentinel to detect and respond to initial access attempts.

• Azure Solution:

  • Configure Azure Sentinel playbooks to disable accounts or revoke access tokens upon suspicious logins.

  • Monitor activity logs for signs of brute force or unauthorized access attempts.

  • Integrate Defender for Cloud with Sentinel to enhance visibility and response capabilities.

11. Ensure Tenant Access Has Least Privilege Access

Mitigates: Technique: T1199 - Trusted Relationship

• Action: Review Tenant Access Policies

• Azure Solution:

  • Configure access policies with least privilege.

  • Monitor Sign-In logs for signs of brute force or unauthorized access attempts

  • Integrate Defender for Identity to detect suspicious behavior.

  • Review Activity logs for any suspicious behavior by '#EXT' users

Summary of Defensive Measures for TA0001

Defensive Strategy	Mitigates	Azure Solution
Secure Public-Facing Applications	T1190 - Exploit Public-Facing Application	Use WAF and Defender for App Services
Enforce Multi-Factor Authentication	T1078 - Valid Accounts	Use Conditional Access and Identity Protection
Harden Remote Services	T1133 - External Remote Services	Apply JIT access and restrict Bastion access
Detect and Block Phishing	T1566 - Phishing	Use Defender for O365 to block phishing emails
Monitor OAuth Grants and Permissions	T1199 - Trusted Relationship	Use Azure Activity logs to detect OAuth consent phishing
Rotate and Monitor Credentials	T1078 - Valid Accounts	Use Key Vault for secret management and rotation
Apply Conditional Access Policies	T1199 - Trusted Relationship	Block access from untrusted devices and networks
Secure DevOps Pipelines	T1195 - Supply Chain Compromise	Use Azure DevOps to scan images and Key Vault for secrets management.
Block Legacy Authentication Protocols	T1078.002 - Domain Accounts	Disable basic authentication protocols
Automate Detection and Response	T1133 - External Remote Services	Use Sentinel playbooks for automated incident response
Tenant Access Policies	T1199 - Trusted Relationship	Use Least Privilege and MFA