Event Triggered Execution: PowerShell Profile

Adversaries may gain persistence and elevate privileges by executing malicious content triggered by PowerShell profiles. A PowerShell profile (profile.ps1) is a script that runs when PowerShell starts and can be used as a logon script to customize user environments.

PowerShell supports several profiles depending on the user or host program. For example, there can be different profiles for PowerShell host programs such as the PowerShell console, PowerShell ISE or Visual Studio Code. An administrator can also configure a profile that applies to all users and host programs on the local computer. [1]

Adversaries may modify these profiles to include arbitrary commands, functions, modules, and/or PowerShell drives to gain persistence. Every time a user opens a PowerShell session the modified script will be executed unless the -NoProfile flag is used when it is launched. [2]

An adversary may also be able to escalate privileges if a script in a PowerShell profile is loaded and executed by an account with higher privileges, such as a domain administrator. [3]

ID: T1546.013
Sub-technique of:  T1546
Platforms: Windows
Permissions Required: Administrator, User
Contributors: Allen DeRyke, ICE
Version: 1.0
Created: 24 January 2020
Last Modified: 24 March 2020
Provided by LAYER 8

Procedure Examples

ID Name Description
G0010 Turla

Turla has used PowerShell profiles to maintain persistence on an infected machine.[2]

Mitigations

ID Mitigation Description
M1045 Code Signing

Enforce execution of only signed PowerShell scripts. Sign profiles to avoid them from being modified.

M1022 Restrict File and Directory Permissions

Making PowerShell profiles immutable and only changeable by certain administrators will limit the ability for adversaries to easily create user level persistence.

M1054 Software Configuration

Avoid PowerShell profiles if not needed. Use the -No Profile flag with when executing PowerShell scripts remotely to prevent local profiles and scripts from being executed.

Detection

ID Data Source Data Component
DS0017 Command Command Execution
DS0022 File File Creation
File Modification
DS0009 Process Process Creation

Locations where profile.ps1 can be stored should be monitored for new profiles or modifications. [4] Example profile locations include:

  • $PsHome\Profile.ps1
  • $PsHome\Microsoft.{{HostProgram}}_profile.ps1
  • $Home\My Documents\PowerShell\Profile.ps1
  • $Home\My Documents\PowerShell\Microsoft.{{HostProgram}}_profile.ps1

Monitor abnormal PowerShell commands, unusual loading of PowerShell drives or modules, and/or execution of unknown programs.

References