PowerShell, with its powerful scripting capabilities, can be both a helpful tool and a potential security risk. To mitigate these risks, it’s crucial to follow best practices for security when using PowerShell. In this article, we’ll share tips and guidelines to help you keep your PowerShell usage secure.
Understand and use ExecutionPolicy
PowerShell’s execution policy is a safety feature that controls the conditions under which PowerShell loads configuration files and runs scripts. Understand the different execution policy levels and set it appropriately for your needs. To view the current execution policy, you can use the Get-ExecutionPolicy cmdlet:
Get-ExecutionPolicyHowever, don’t rely solely on execution policy for security, as it can be bypassed.
Utilize secure strings for sensitive data
When you need to store sensitive data in your scripts, such as passwords, use the secure string cmdlet ConvertTo-SecureString. Secure strings are encrypted with the Windows Data Protection API, providing a layer of security for your sensitive data:
$SecurePassword = ConvertTo-SecureString -String "PlainTextPassword" -AsPlainText -ForceLeverage Just Enough Administration (JEA)
Just Enough Administration (JEA) is a PowerShell toolkit that provides a way to delegate administration tasks using constrained sessions. These sessions limit what a user can do based on a predefined set of capabilities. JEA helps to implement the principle of least privilege and reduces the risks associated with administrative rights.
Validate input
Scripts that accept input are vulnerable to injection attacks. Always validate input to ensure it’s in the expected format and contains expected values. This can prevent malicious code from being run through your scripts.
Limit the use of plain text credentials
Where possible, avoid using plain text credentials in your scripts. Instead, use Windows integrated authentication or certificate-based authentication. If you must use credentials, consider using the Get-Credential cmdlet to prompt for credentials during runtime:
$credential = Get-CredentialEnable and monitor PowerShell logging
PowerShell provides several logging options, including script block logging, module logging, and transcription. Enabling these can provide a trail of activity and can be invaluable in identifying malicious activity. The logs can be viewed in the Event Viewer under “Windows Logs” > “Application and Services Logs” > “Microsoft” > “Windows” > “PowerShell”.
Regularly update PowerShell
As with any software, keep your PowerShell environment up-to-date. Updates often include security enhancements and patches for known vulnerabilities. Check for updates regularly and apply them in a timely manner.
Conclusion
PowerShell is a powerful tool in the hands of IT professionals, but like any powerful tool, it can be a double-edged sword. Following best practices for security can help you use PowerShell effectively and safely.
More resources
- about_Execution_Policies | learn.microsoft.com
- Microsoft.PowerShell.Security | learn.microsoft.com
- Just Enough Administration (JEA) | learn.microsoft.com
- How to validate parameter input | learn.microsoft.com
- about_Logging_Windows | learn.microsoft.com
- about_Logging_Non-Windows | learn.microsoft.com