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)
View in MITRE ATT&CK®| Capability ID | Capability Description | Mapping Type | ATT&CK ID | ATT&CK Name | Notes |
|---|---|---|---|---|---|
| azure_security_center_recommendations | Azure Security Center Recommendations | technique_scores | T1556.003 | Pluggable Authentication Modules |
Comments
This control's "Immutable (read-only) root filesystem should be enforced for containers" recommendation can lead to preventing this sub-technique which often modifies Pluggable Authentication Modules (PAM) components in the file system. Because this is a recommendation, and specific to Kubernetes containers, its score is assessed as Minimal.
References
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| file_integrity_monitoring | File Integrity Monitoring | technique_scores | T1556.003 | Pluggable Authentication Modules |
Comments
The PAM configuration and module paths (/etc/pam.d/) can be monitored for changes using this control. The files in this path should not change often and therefore false positives should be minimal. This control at worst scans for changes on an hourly basis.
References
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