Course 30 - Practical Malware Development - Beginner Level | Episode 2: Mastering C# System Control: Navigating, Enumerating, and Executing

In this lesson, you’ll learn about: Detecting and defending against system control techniques1. Directory Navigation & Enumeration (Detection)

What attackers typically do:
- List files and directories
- Change working directories to explore the system
Why it matters:
- Helps locate sensitive files (credentials, configs, backups)
Defensive strategies:
- Monitor processes accessing large numbers of files
- Detect unusual access to:
  - System directories
  - User profile folders
- Use file integrity monitoring (FIM) tools

2. System Information Retrieval (Reconnaissance Detection)

Common data collected:
- Hostname, username, OS version
- Running processes and privileges
Why it matters:
- Enables privilege escalation and tailored attacks
Defensive strategies:
- Use EDR solutions to detect:
  - Scripts or processes querying system info repeatedly
- Monitor abnormal use of:
  - Environment variables
  - Process enumeration APIs

3. Command Execution via Shell (High-Risk Behavior)

Typical attacker behavior:
- Launching cmd.exe or PowerShell silently
- Redirecting output for remote use
Red flags:
- Hidden or background shell execution
- Non-interactive processes spawning command shells
Defensive strategies:
- Enable logging:
  - Process creation events (e.g., Event ID 4688)
- Detect:
  - Parent-child anomalies (e.g., Office → cmd.exe)
- Use:
  - Application allowlisting
  - PowerShell constrained language mode

4. Command Parsing & Remote Control Patterns

Behavior pattern:
- Program receives commands → parses them → executes locally
Indicators of compromise (IOCs):
- Repeated outbound connections to a single endpoint
- Commands executed without user interaction
- Consistent “beaconing” intervals
Defensive strategies:
- Monitor network traffic patterns (C2 detection)
- Apply egress filtering (block unknown outbound traffic)
- Use behavioral analytics to detect automation patterns

Key Takeaways

These techniques represent core attacker tradecraft:
- File system exploration
- System reconnaissance
- Command execution
Strong defense relies on:
- Visibility (logs, EDR, network monitoring)
- Control (least privilege, allowlisting)
- Detection (behavior-based alerts, anomaly detection)

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