Creation or Modification of Pluggable Authentication Module or Configuration

Last updated 7 months ago on 2025-01-15
Created a year ago on 2024-03-06

About

This rule monitors for the creation or modification of Pluggable Authentication Module (PAM) shared object files or configuration files. Attackers may create or modify these files to maintain persistence on a compromised system, or harvest account credentials.
Tags
Domain: EndpointOS: LinuxUse Case: Threat DetectionTactic: Credential AccessTactic: PersistenceData Source: Elastic DefendLanguage: eql
Severity
medium
Risk Score
47
MITRE ATT&CK™

Persistence (TA0003)(opens in a new tab or window)

Credential Access (TA0006)(opens in a new tab or window)

False Positive Examples
Trusted system module updates or allowed Pluggable Authentication Module (PAM) daemon configuration changes.
License
Elastic License v2(opens in a new tab or window)

Definition

Rule Type
Event Correlation Rule
Integration Pack
Prebuilt Security Detection Rules
Index Patterns
logs-endpoint.events.file*
Related Integrations

endpoint(opens in a new tab or window)

Query
file where host.os.type == "linux" and event.action in ("rename", "creation") and
process.executable != null and (
  (file.path like~ (
    "/lib/security/*", "/lib64/security/*", "/usr/lib/security/*", "/usr/lib64/security/*",
    "/lib/x86_64-linux-gnu/security/*", "/usr/lib/x86_64-linux-gnu/security/*"
  ) and file.extension == "so") or
  (file.path like~ "/etc/pam.d/*" and file.extension == null) or
  (file.path like~ "/etc/security/pam_*" or file.path == "/etc/pam.conf")
) and not (
  process.executable in (
    "/bin/dpkg", "/usr/bin/dpkg", "/bin/dockerd", "/usr/bin/dockerd", "/usr/sbin/dockerd", "/bin/microdnf",
    "/usr/bin/microdnf", "/bin/rpm", "/usr/bin/rpm", "/bin/snapd", "/usr/bin/snapd", "/bin/yum", "/usr/bin/yum",
    "/bin/dnf", "/usr/bin/dnf", "/bin/podman", "/usr/bin/podman", "/bin/dnf-automatic", "/usr/bin/dnf-automatic",
    "/bin/pacman", "/usr/bin/pacman", "/usr/bin/dpkg-divert", "/bin/dpkg-divert", "/sbin/apk", "/usr/sbin/apk",
    "/usr/local/sbin/apk", "/usr/bin/apt", "/usr/sbin/pacman", "/bin/podman", "/usr/bin/podman", "/usr/bin/puppet",
    "/bin/puppet", "/opt/puppetlabs/puppet/bin/puppet", "/usr/bin/chef-client", "/bin/chef-client",
    "/bin/autossl_check", "/usr/bin/autossl_check", "/proc/self/exe", "/dev/fd/*",  "/usr/bin/pamac-daemon",
    "/bin/pamac-daemon", "/usr/lib/snapd/snapd", "/usr/local/bin/dockerd", "/usr/sbin/pam-auth-update",
    "/usr/lib/systemd/systemd", "/usr/libexec/packagekitd", "/usr/bin/bsdtar", "/sbin/pam-auth-update"
  ) or
  file.path like (
    "/tmp/snap.rootfs_*/pam_*.so", "/tmp/newroot/lib/*/pam_*.so", "/tmp/newroot/usr/lib64/security/pam_*.so"
  ) or
  file.extension in ("swp", "swpx", "swx", "dpkg-remove") or
  file.Ext.original.extension == "dpkg-new" or
  process.executable like (
    "/nix/store/*", "/var/lib/dpkg/*", "/snap/*", "/dev/fd/*", "/usr/lib/virtualbox/*"
  ) or
  (process.name == "sed" and file.name like~ "sed*") or
  (process.name == "perl" and file.name like~ "e2scrub_all.tmp*")
)

Install detection rules in Elastic Security

Detect Creation or Modification of Pluggable Authentication Module or Configuration in the Elastic Security detection engine by installing this rule into your Elastic Stack.

To setup this rule, check out the installation guide for Prebuilt Security Detection Rules(opens in a new tab or window).