Adversaries may modify pluggable authentication modules (PAM) to access user credentials or enable otherwise unwarranted access to accounts. PAM is a modular system of configuration files, libraries, and executable files which guide authentication for many services. The most common authentication module is <code>pam_unix.so</code>, which retrieves, sets, and verifies account authentication information in <code>/etc/passwd</code> and <code>/etc/shadow</code>.(Citation: Apple PAM)(Citation: Man Pam_Unix)(Citation: Red Hat PAM)
Adversaries may modify components of the PAM system to create backdoors. PAM components, such as <code>pam_unix.so</code>, can be patched to accept arbitrary adversary supplied values as legitimate credentials.(Citation: PAM Backdoor)
Malicious modifications to the PAM system may also be abused to steal credentials. Adversaries may infect PAM resources with code to harvest user credentials, since the values exchanged with PAM components may be plain-text since PAM does not store passwords.(Citation: PAM Creds)(Citation: Apple PAM)
Detect Malicious Modification of Pluggable Authentication Modules (PAM)
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:
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):
Authentication Tools and Methods:
Secure Legacy Systems:
Monitoring and Alerting:
Training and Policy Enforcement:
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:
Credential Security:
Multi-Factor Authentication (MFA):
Privileged Access Management (PAM):
Auditing and Monitoring:
Just-In-Time Access:
Tools for Implementation
Privileged Access Management (PAM):
Credential Management:
Multi-Factor Authentication:
Linux Privilege Management:
Just-In-Time Access: