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ATT&CK Technique

Kernel Modules and Extensions

T1547.006 · persistence, privilege-escalation

Adversaries may modify the kernel to automatically execute programs on system boot. Loadable Kernel Modules (LKMs) are pieces of code that can be loaded and unloaded into the kernel upon demand. They extend the functionality of the kernel without the need to reboot the system.

For example, one type of module is the device driver, which allows the kernel to access hardware connected to the system. When used maliciously, LKMs can be a type of kernel-mode Rootkit that run with the highest operating system privilege (Ring 0). Common features of LKM based rootkits include: hiding itself, selective hiding of files, processes and network activity, as well as log tampering, providing authenticated backdoors, and enabling root access to non-privileged users. Kernel extensions, also called kext, are used in macOS to load functionality onto a system similar to LKMs for Linux. Since the kernel is responsible for enforcing security and the kernel extensions run as apart of the kernel, kexts are not governed by macOS security policies.

Kexts are loaded and unloaded through kextload and kextunload commands. Kexts need to be signed with a developer ID that is granted privileges by Apple allowing it to sign Kernel extensions. Developers without these privileges may still sign kexts but they will not load unless SIP is disabled.

If SIP is enabled, the kext signature is verified before being added to the AuxKC. Since macOS Catalina 10.15, kernel extensions have been deprecated in favor of System Extensions. However, kexts are still allowed as "Legacy System Extensions" since there is no System Extension for Kernel Programming Interfaces.

Adversaries can use LKMs and kexts to conduct Persistence and/or Privilege Escalation on a system. Examples have been found in the wild, and there are some relevant open source projects as well.

macOSLinux
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Actors Using This

1
chinaDaggerfly
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Atomic Tests

4
Executable Atomic Red Team test cases for exercising this technique in a lab. Copy a command, run it on the listed platform, confirm your detections fire.
bashelevatedlinuxLinux - Load Kernel Module via insmod
This test uses the insmod command to load a kernel module for Linux. 
sudo insmod #{module_path}
bashelevatedmacosMacOS - Load Kernel Module via kextload and kmutil
This test uses the kextload and kmutil commands to load and unload a MacOS kernel module. 
set -x
sudo kextload #{module_path}
kextstat 2>/dev/null | grep SoftRAID
sudo kextunload #{module_path}
sudo kmutil load -p #{module_path}
kextstat 2>/dev/null | grep SoftRAID
sudo kmutil unload -p #{module_path}
bashelevatedmacosMacOS - Load Kernel Module via KextManagerLoadKextWithURL()
This test uses the IOKit API to load a kernel module for macOS. Harcoded to use SoftRAID kext 
sudo #{exe_path}
kextstat 2>/dev/null | grep SoftRAID
sudo kextunload /Library/Extensions/SoftRAID.kext
powershellelevatedwindowsSnake Malware Kernel Driver Comadmin
The following Atomic Test will write an file, comadmin.dat, to disk. From the report, Snake's installer drops the kernel driver and a custom DLL which is used to load the driver into a single AES encrypted file on disk. Typically, this file is named “comadmin.dat” and is stored in the %windows%\system32\Com directory. This Atomic Test will write a hardcoded named file to disk in the com directory named comadmin.dat. [Snake Malware - CISA](https://media.defense.gov/2023/May/09/2003218554/-1/-1/0/JOINT_CSA_HUNTING_RU_INTEL_SNAKE_MALWARE_20230509.PDF) 
$examplePath = Join-Path $env:windir "system32\Com"; if (-not (Test-Path $examplePath)) { New-Item -ItemType Directory -Path $examplePath | Out-Null }; $exampleName = "comadmin.dat"; $exampleFullPath = Join-Path $examplePath $exampleName; $randomBytes = New-Object Byte[] 0x1000; (New-Object Random).NextBytes($randomBytes); [System.IO.File]::WriteAllBytes($exampleFullPath, $randomBytes)
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Mitigations

4
MITRE ATT&CK mitigations - vendor-agnostic guidance for reducing exposure to this technique.
M1018User Account Management

User Account Management involves implementing and enforcing policies for the lifecycle of user accounts, including creation, modification, and deactivation. Proper account management reduces the attack surface by limiting unauthorized access, managing account privileges, and ensuring accounts are used according to organizational policies.

Enforcing the Principle of Least Privilege
  • Implementation: Assign users only the minimum permissions required to perform their job functions. Regularly audit accounts to ensure no excess permissions are granted.
  • Use Case: Reduces the risk of privilege escalation by ensuring accounts cannot perform unauthorized actions. Implementing Strong Password Policies.
  • Implementation: Enforce password complexity requirements (e.g., length, character types). Require password expiration every 90 days and disallow password reuse.
  • Use Case: Prevents adversaries from gaining unauthorized access through password guessing or brute force attacks. Managing Dormant and Orphaned Accounts.
  • Implementation: Implement automated workflows to disable accounts after a set period of inactivity (e.g., 30 days). Remove orphaned accounts (e.g., accounts without an assigned owner) during regular account audits.
  • Use Case: Eliminates dormant accounts that could be exploited by attackers. Account Lockout Policies.
  • Implementation: Configure account lockout thresholds (e.g., lock accounts after five failed login attempts). Set lockout durations to a minimum of 15 minutes.
  • Use Case: Mitigates automated attack techniques that rely on repeated login attempts. Multi-Factor Authentication (MFA) for High-Risk Accounts.
  • Implementation: Require MFA for all administrative accounts and high-risk users. Use MFA mechanisms like hardware tokens, authenticator apps, or biometrics.
  • Use Case: Prevents unauthorized access, even if credentials are stolen. Restricting Interactive Logins.
  • Implementation: Restrict interactive logins for privileged accounts to specific secure systems or management consoles. Use group policies to enforce logon restrictions.
  • Use Case: Protects sensitive accounts from misuse or exploitation.
Tools for Implementation Built-in Tools
  • Microsoft Active Directory (AD): Centralized account management and RBAC enforcement.
  • Group Policy Object (GPO): Enforce password policies, logon restrictions, and account lockout policies.
Identity and Access Management (IAM) Tools
  • Okta: Centralized user provisioning, MFA, and SSO integration.
  • Microsoft Azure Active Directory: Provides advanced account lifecycle management, role-based access, and conditional access policies.
Privileged Account Management (PAM)
  • CyberArk, BeyondTrust, Thycotic: Manage and monitor privileged account usage, enforce session recording, and JIT access.
M1026Privileged 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.

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.
M1038Execution Prevention

Prevent the execution of unauthorized or malicious code on systems by implementing application control, script blocking, and other execution prevention mechanisms. This ensures that only trusted and authorized code is executed, reducing the risk of malware and unauthorized actions.

Application Control
  • Use Case: Use tools like AppLocker or Windows Defender Application Control (WDAC) to create whitelists of authorized applications and block unauthorized ones. On Linux, use tools like SELinux or AppArmor to define mandatory access control policies for application execution.
  • Implementation: Allow only digitally signed or pre-approved applications to execute on servers and endpoints. (e.g., `New-AppLockerPolicy -PolicyType Enforced -FilePath "C:\Policies\AppLocker.
xml"`) Script Blocking
  • Use Case: Use script control mechanisms to block unauthorized execution of scripts, such as PowerShell or JavaScript. Web Browsers: Use browser extensions or settings to block JavaScript execution from untrusted sources.
  • Implementation: Configure PowerShell to enforce Constrained Language Mode for non-administrator users. (e.g.
, Set-ExecutionPolicy AllSigned) Executable Blocking
  • Use Case: Prevent execution of binaries from suspicious locations, such as %TEMP% or %APPDATA% directories.
  • Implementation: Block execution of .exe, .bat, or .ps1 files from user-writable directories.
Dynamic Analysis Prevention
  • Use Case: Use behavior-based execution prevention tools to identify and block malicious activity in real time.
  • Implemenation: Employ EDR solutions that analyze runtime behavior and block suspicious code execution.
M1049Antivirus/Antimalware

Antivirus/Antimalware solutions utilize signatures, heuristics, and behavioral analysis to detect, block, and remediate malicious software, including viruses, trojans, ransomware, and spyware. These solutions continuously monitor endpoints and systems for known malicious patterns and suspicious behaviors that indicate compromise. Antivirus/Antimalware software should be deployed across all devices, with automated updates to ensure protection against the latest threats.

Signature-Based Detection
  • Implementation: Use predefined signatures to identify known malware based on unique patterns such as file hashes, byte sequences, or command-line arguments. This method is effective against known threats.
  • Use Case: When malware like "Emotet" is detected, its signature (such as a specific file hash) matches a known database of malicious software, triggering an alert and allowing immediate quarantine of the infected file.
Heuristic-Based Detection
  • Implementation: Deploy heuristic algorithms that analyze behavior and characteristics of files and processes to identify potential malware, even if it doesn’t match a known signature.
  • Use Case: If a program attempts to modify multiple critical system files or initiate suspicious network communications, heuristic analysis may flag it as potentially malicious, even if no specific malware signature is available.
Behavioral Detection (Behavior Prevention)
  • Implementation: Use behavioral analysis to detect patterns of abnormal activities, such as unusual system calls, unauthorized file encryption, or attempts to escalate privileges.
  • Use Case: Behavioral analysis can detect ransomware attacks early by identifying behavior like mass file encryption, even before a specific ransomware signature has been identified.
Real-Time Scanning
  • Implementation: Enable real-time scanning to automatically inspect files and network traffic for signs of malware as they are accessed, downloaded, or executed.
  • Use Case: When a user downloads an email attachment, the antivirus solution scans the file in real-time, checking it against both signatures and heuristics to detect any malicious content before it can be opened.
Cloud-Assisted Threat Intelligence
  • Implementation: Use cloud-based threat intelligence to ensure the antivirus solution can access the latest malware definitions and real-time threat feeds from a global database of emerging threats.
  • Use Case: Cloud-assisted antivirus solutions quickly identify newly discovered malware by cross-referencing against global threat databases, providing real-time protection against zero-day attacks.
Tools for Implementation
  • Endpoint Security Platforms: Use solutions such as EDR for comprehensive antivirus/antimalware protection across all systems.
  • Centralized Management: Implement centralized antivirus management consoles that provide visibility into threat activity, enable policy enforcement, and automate updates.
  • Behavioral Analysis Tools: Leverage solutions with advanced behavioral analysis capabilities to detect malicious activity patterns that don’t rely on known signatures.
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Detection Coverage

1/6 layers
Coverage across standard detection surfaces. Rows marked none have no rule of that type mapped. Some are real blind spots worth closing; others are simply not applicable to this technique (e.g. YARA matches malware files, not network behaviour).
Behavioral / log (Sigma) 1
Analytics (MITRE CAR) none
Runtime / container (Falco) none
File / malware (YARA) none
Network (Suricata/Snort) none
Vuln scan (Nuclei) none
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