[New Rules] PAM Module Creation & Unusual PAM Grantor (#3743)

* [New Rules] PAM Module Creation & Unusual PAM Grantor

* Update persistence_unusual_pam_grantor.toml

* Update persistence_pluggable_authentication_module_creation.toml

* Update rules/linux/persistence_pluggable_authentication_module_creation.toml

* Update persistence_pluggable_authentication_module_creation.toml

* Update persistence_unusual_pam_grantor.toml

* Update rules/linux/persistence_pluggable_authentication_module_creation.toml

(cherry picked from commit c87c4c9)

rules/linux/persistence_pluggable_authentication_module_creation.toml

@@ -0,0 +1,97 @@
+[metadata]
+creation_date = "2024/03/06"
+integration = ["endpoint"]
+maturity = "production"
+updated_date = "2024/03/06"
+
+[rule]
+author = ["Elastic"]
+description = """
+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.
+"""
+false_positives = [
+    "Trusted system module updates or allowed Pluggable Authentication Module (PAM) daemon configuration changes.",
+]
+from = "now-9m"
+index = ["logs-endpoint.events.file*"]
+language = "eql"
+license = "Elastic License v2"
+name = "Creation or Modification of Pluggable Authentication Module or Configuration"
+references = [
+    "https://github.com/zephrax/linux-pam-backdoor",
+    "https://github.com/eurialo/pambd",
+    "http://0x90909090.blogspot.com/2016/06/creating-backdoor-in-pam-in-5-line-of.html",
+    "https://www.trendmicro.com/en_us/research/19/i/skidmap-linux-malware-uses-rootkit-capabilities-to-hide-cryptocurrency-mining-payload.html",
+]
+risk_score = 47
+rule_id = "f48ecc44-7d02-437d-9562-b838d2c41987"
+severity = "medium"
+tags = [
+    "Domain: Endpoint",
+    "OS: Linux",
+    "Use Case: Threat Detection",
+    "Tactic: Credential Access",
+    "Tactic: Persistence",
+    "Data Source: Elastic Defend",
+]
+timestamp_override = "event.ingested"
+type = "eql"
+query = '''
+file where host.os.type == "linux" and event.action in ("rename", "creation") and 
+process.executable != null and (
+  (file.path : ("/lib/security/*", "/lib64/security/*", "/usr/lib/security/*", "/usr/lib64/security/*",
+  "/usr/lib/x86_64-linux-gnu/security/*") and file.extension == "so") or
+  (file.path : "/etc/pam.d/*" and file.extension == null) or 
+  (file.path : "/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"
+  ) or
+  file.path : (
+    "/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 : (
+    "/nix/store/*", "/var/lib/dpkg/*", "/snap/*", "/dev/fd/*", "/usr/lib/virtualbox/*"
+  ) or
+  (process.name == "sed" and file.name : "sed*") or
+  (process.name == "perl" and file.name : "e2scrub_all.tmp*") 
+)
+'''
+
+[[rule.threat]]
+framework = "MITRE ATT&CK"
+
+[[rule.threat.technique]]
+id = "T1543"
+name = "Create or Modify System Process"
+reference = "https://attack.mitre.org/techniques/T1543/"
+
+[rule.threat.tactic]
+id = "TA0003"
+name = "Persistence"
+reference = "https://attack.mitre.org/tactics/TA0003/"
+
+[[rule.threat]]
+framework = "MITRE ATT&CK"
+
+[[rule.threat.technique]]
+id = "T1556"
+name = "Modify Authentication Process"
+reference = "https://attack.mitre.org/techniques/T1556/"
+
+[rule.threat.tactic]
+id = "TA0006"
+name = "Credential Access"
+reference = "https://attack.mitre.org/tactics/TA0006/"

rules/linux/persistence_unusual_pam_grantor.toml

@@ -0,0 +1,83 @@
+[metadata]
+creation_date = "2024/03/06"
+integration = ["auditd_manager"]
+maturity = "production"
+min_stack_comments = "Multiple field support in the New Terms rule type was added in Elastic 8.6"
+min_stack_version = "8.6.0"
+updated_date = "2024/03/06"
+
+[rule]
+author = ["Elastic"]
+description = """
+This rule detects successful authentications via PAM grantors that are not commonly used. This could indicate an
+attacker is attempting to escalate privileges or maintain persistence on the system by modifying the default PAM
+configuration.
+"""
+from = "now-9m"
+index = ["auditbeat-*", "logs-auditd_manager.auditd-*"]
+language = "kuery"
+license = "Elastic License v2"
+name = "Authentication via Unusual PAM Grantor"
+risk_score = 47
+rule_id = "a8aaa49d-9834-462d-bf8f-b1255cebc004"
+setup = """## Setup
+This rule requires the use of the `auditd_manager` integration. `Auditd_manager` is a tool designed to simplify and enhance the management of the audit subsystem in Linux systems. It provides a user-friendly interface and automation capabilities for configuring and monitoring system auditing through the auditd daemon. With `auditd_manager`, administrators can easily define audit rules, track system events, and generate comprehensive audit reports, improving overall security and compliance in the system. The following steps should be executed in order to install and deploy `auditd_manager` on a Linux system.
+```
+Kibana -->
+Management -->
+Integrations -->
+Auditd Manager -->
+Add Auditd Manager
+```
+`Auditd_manager` subscribes to the kernel and receives events as they occur without any additional configuration. However, if more advanced configuration is required to detect specific behavior, audit rules can be added to the integration in either the "audit rules" configuration box or the "auditd rule files" box by specifying a file to read the audit rules from.
+For this detection rule to trigger, no additional configuration is required.
+"""
+severity = "medium"
+tags = [
+    "Domain: Endpoint",
+    "OS: Linux",
+    "Use Case: Threat Detection",
+    "Tactic: Credential Access",
+    "Tactic: Persistence",
+    "Data Source: Auditd Manager",
+]
+timestamp_override = "event.ingested"
+type = "new_terms"
+query = '''
+event.category:authentication and host.os.type:linux and event.action:authenticated and event.outcome:success and
+auditd.data.grantors:(* and not (pam_rootok or *pam_cap* or *pam_permit*))
+'''
+
+[[rule.threat]]
+framework = "MITRE ATT&CK"
+
+[[rule.threat.technique]]
+id = "T1543"
+name = "Create or Modify System Process"
+reference = "https://attack.mitre.org/techniques/T1543/"
+
+[rule.threat.tactic]
+id = "TA0003"
+name = "Persistence"
+reference = "https://attack.mitre.org/tactics/TA0003/"
+
+[[rule.threat]]
+framework = "MITRE ATT&CK"
+
+[[rule.threat.technique]]
+id = "T1556"
+name = "Modify Authentication Process"
+reference = "https://attack.mitre.org/techniques/T1556/"
+
+[rule.threat.tactic]
+id = "TA0006"
+name = "Credential Access"
+reference = "https://attack.mitre.org/tactics/TA0006/"
+
+[rule.new_terms]
+field = "new_terms_fields"
+value = ["auditd.data.grantors", "agent.id"]
+
+[[rule.new_terms.history_window_start]]
+field = "history_window_start"
+value = "now-14d"