Adversaries may simulate keystrokes on a victim’s computer by various means to perform any type of action on behalf of the user, such as launching the command interpreter using keyboard shortcuts, typing an inline script to be executed, or interacting directly with a GUI-based application. These actions can be preprogrammed into adversary tooling or executed through physical devices such as Human Interface Devices (HIDs). For example, adversaries have used tooling that monitors the Windows message loop to detect when a user visits bank-specific URLs. If detected, the tool then simulates keystrokes to open the developer console or select the address bar, pastes malicious JavaScript from the clipboard, and executes it - enabling manipulation of content within the browser, such as replacing bank account numbers during transactions.(Citation: BleepingComputer BackSwap)(Citation: welivesecurity BackSwap) Adversaries have also used malicious USB devices to emulate keystrokes that launch PowerShell, leading to the download and execution of malware from adversary-controlled servers.(Citation: BleepingComputer USB)
Detects suspicious USB HID device enumeration and keystroke injection patterns, such as rapid sequences of input with no user context, scripts executed through simulated keystrokes, or rogue devices presenting themselves as keyboards.
Detects abnormal HID device enumeration via I/O Registry (ioreg -p IOUSB) and keystroke injection targeting AppleScript, osascript, or PowerShell equivalents. Defender correlates new USB device connections with rapid script execution.
Detects USB HID device enumeration under `/sys/bus/usb/devices/` and rapid keystroke injection resulting in command execution such as bash or Python scripts launched without interactive user activity.
Limit Hardware Installation
Prevent unauthorized users or groups from installing or using hardware, such as external drives, peripheral devices, or unapproved internal hardware components, by enforcing hardware usage policies and technical controls. This includes disabling USB ports, restricting driver installation, and implementing endpoint security tools to monitor and block unapproved devices. This mitigation can be implemented through the following measures: Disable USB Ports and Hardware Installation Policies: - Use Group Policy Objects (GPO) to disable USB mass storage devices: - Navigate to Computer Configuration > Administrative Templates > System > Removable Storage Access. - Deny write and read access to USB devices. - Whitelist approved devices using unique serial numbers via Windows Device Installation Policies. Deploy Endpoint Protection and Device Control Solutions: - Use tools like Microsoft Defender for Endpoint, Symantec Endpoint Protection, or Tanium to monitor and block unauthorized hardware. - Implement device control policies to allow specific hardware types (e.g., keyboards, mice) and block others. Harden BIOS/UEFI and System Firmware: - Set strong passwords for BIOS/UEFI access. - Enable Secure Boot to prevent rogue hardware components from loading unauthorized firmware. Restrict Peripheral Devices and Drivers: - Use Windows Device Manager Policies to block installation of unapproved drivers. - Monitor hardware installation attempts through endpoint monitoring tools. Disable Bluetooth and Wireless Hardware: - Use GPO or MDM tools to disable Bluetooth and Wi-Fi interfaces across systems. - Restrict hardware pairing to approved devices only. Logging and Monitoring: - Enable logging for hardware installation events in Windows Event Logs (Event ID 20001 for Device Setup Manager). - Use SIEM solutions (e.g., Splunk, Elastic Stack) to detect unauthorized hardware installation activities. *Tools for Implementation* USB and Device Control: - Microsoft Group Policy Objects (GPO) - Microsoft Defender for Endpoint - Symantec Endpoint Protection - McAfee Device Control Endpoint Monitoring: - EDRs - OSSEC (open-source host-based IDS) Hardware Whitelisting: - BitLocker for external drives (Windows) - Windows Device Installation Policies - Device Control BIOS/UEFI Security: - Secure Boot (Windows/Linux) Firmware management tools like Dell Command Update or HP Sure Start
Execution 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. This mitigation can be implemented through the following measures: 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.