Sudo and Sudo Caching

Behavioral Detection Strategy for Abuse of Sudo and Sudo Caching

Restrict File and Directory Permissions: Restricting file and directory permissions involves setting access controls at the file system level to limit which users, groups, or processes can read, write, or execute files. By configuring permissions appropriately, organizations can reduce the attack surface for adversaries seeking to access sensitive data, plant malicious code, or tamper with system files.

Enforce Least Privilege Permissions:

• Remove unnecessary write permissions on sensitive files and directories.
• Use file ownership and groups to control access for specific roles.

Example (Windows): Right-click the shared folder → Properties → Security tab → Adjust permissions for NTFS ACLs.

Harden File Shares:

• Disable anonymous access to shared folders.
• Enforce NTFS permissions for shared folders on Windows.

Example: Set permissions to restrict write access to critical files, such as system executables (e.g., /bin or /sbin on Linux). Use tools like chown and chmod to assign file ownership and limit access.

On Linux, apply: chmod 750 /etc/sensitive.conf chown root:admin /etc/sensitive.conf

File Integrity Monitoring (FIM):

• Use tools like Tripwire, Wazuh, or OSSEC to monitor changes to critical file permissions.

Audit File System Access:

• Enable auditing to track permission changes or unauthorized access attempts.
• Use auditd (Linux) or Event Viewer (Windows) to log activities.

Restrict Startup Directories:

• Configure permissions to prevent unauthorized writes to directories like C:\ProgramData\Microsoft\Windows\Start Menu.

Example: Restrict write access to critical directories like /etc/, /usr/local/, and Windows directories such as C:\Windows\System32.

• On Windows, use icacls to modify permissions: icacls "C:\Windows\System32" /inheritance:r /grant:r SYSTEM:(OI)(CI)F
• On Linux, monitor permissions using tools like lsattr or auditd.

Operating System Configuration: Operating System Configuration involves adjusting system settings and hardening the default configurations of an operating system (OS) to mitigate adversary exploitation and prevent abuse of system functionality. Proper OS configurations address security vulnerabilities, limit attack surfaces, and ensure robust defense against a wide range of techniques. This mitigation can be implemented through the following measures:

Disable Unused Features:

• Turn off SMBv1, LLMNR, and NetBIOS where not needed.
• Disable remote registry and unnecessary services.

Enforce OS-level Protections:

• Enable Data Execution Prevention (DEP), Address Space Layout Randomization (ASLR), and Control Flow Guard (CFG) on Windows.
• Use AppArmor or SELinux on Linux for mandatory access controls.

Secure Access Settings:

• Enable User Account Control (UAC) for Windows.
• Restrict root/sudo access on Linux/macOS and enforce strong permissions using sudoers files.

File System Hardening:

• Implement least-privilege access for critical files and system directories.
• Audit permissions regularly using tools like icacls (Windows) or getfacl/chmod (Linux/macOS).

Secure Remote Access:

• Restrict RDP, SSH, and VNC to authorized IPs using firewall rules.
• Enable NLA for RDP and enforce strong password/lockout policies.

Harden Boot Configurations:

• Enable Secure Boot and enforce UEFI/BIOS password protection.
• Use BitLocker or LUKS to encrypt boot drives.

Regular Audits:

• Periodically audit OS configurations using tools like CIS Benchmarks or SCAP tools.

Tools for Implementation

Windows:

• Microsoft Group Policy Objects (GPO): Centrally enforce OS security settings.
• Windows Defender Exploit Guard: Built-in OS protection against exploits.
• CIS-CAT Pro: Audit Windows security configurations based on CIS Benchmarks.

Linux/macOS:

• AppArmor/SELinux: Enforce mandatory access controls.
• Lynis: Perform comprehensive security audits.
• SCAP Security Guide: Automate configuration hardening using Security Content Automation Protocol.

Cross-Platform:

• Ansible or Chef/Puppet: Automate configuration hardening at scale.
• OpenSCAP: Perform compliance and configuration checks.

Privileged Account Management: Privileged Account Management focuses on implementing policies, controls, and tools to securely manage privileged accounts (e.g., SYSTEM, root, or administrative accounts). This includes restricting access, limiting the scope of permissions, monitoring privileged account usage, and ensuring accountability through logging and auditing.This mitigation can be implemented through the following measures:

Account Permissions and Roles:

• Implement RBAC and least privilege principles to allocate permissions securely.
• Use tools like Active Directory Group Policies to enforce access restrictions.

Credential Security:

• Deploy password vaulting tools like CyberArk, HashiCorp Vault, or KeePass for secure storage and rotation of credentials.
• Enforce password policies for complexity, uniqueness, and expiration using tools like Microsoft Group Policy Objects (GPO).

Multi-Factor Authentication (MFA):

• Enforce MFA for all privileged accounts using Duo Security, Okta, or Microsoft Azure AD MFA.

Privileged Access Management (PAM):

• Use PAM solutions like CyberArk, BeyondTrust, or Thycotic to manage, monitor, and audit privileged access.

Auditing and Monitoring:

• Integrate activity monitoring into your SIEM (e.g., Splunk or QRadar) to detect and alert on anomalous privileged account usage.

Just-In-Time Access:

• Deploy JIT solutions like Azure Privileged Identity Management (PIM) or configure ephemeral roles in AWS and GCP to grant time-limited elevated permissions.

Tools for Implementation

Privileged Access Management (PAM):

• CyberArk, BeyondTrust, Thycotic, HashiCorp Vault.

Credential Management:

• Microsoft LAPS (Local Admin Password Solution), Password Safe, HashiCorp Vault, KeePass.

Multi-Factor Authentication:

• Duo Security, Okta, Microsoft Azure MFA, Google Authenticator.

Linux Privilege Management:

• sudo configuration, SELinux, AppArmor.

Just-In-Time Access:

• Azure Privileged Identity Management (PIM), AWS IAM Roles with session constraints, GCP Identity-Aware Proxy.