Destroying EDR with Windows Symbolic Links: Advanced Detection, Mitigation and Prevention

Jan 294 min read

Destroying EDR with Windows Symbolic Links

Destroying EDR with Windows Symbolic LinksYour sophisticated Endpoint Detection and Response (EDR) system, designed to protect against advanced threats, rendered ineffective by a deceptively simple technique. Attackers are weaponizing Windows symbolic links to bypass these defenses, leaving systems vulnerable to stealthy attacks.

This isn’t just a theoretical problem—it’s a growing reality. In this comprehensive guide, I’ll unravel the mechanics of symbolic link abuse, showcase their potential impact, and provide step-by-step solutions to detect, mitigate, and prevent these attacks.

Whether you are a

SOC analyst
Security architect
Threat hunter

this guide is tailored to help you master this evolving threat.

What Are Symbolic Links?

Symbolic links are a feature in Windows that act as shortcuts or references to files and directories. They enable seamless redirection of file operations without duplicating data. While this functionality has legitimate uses, attackers have found ways to exploit it to:

Redirect EDR Operations: Misdirect monitoring tools to safe or unmonitored locations.
Bypass Security Mechanisms: Execute malicious activities undetected.
Obfuscate Attacks: Hide traces and make forensic analysis more challenging.

Think of symbolic links as a digital road sign. When manipulated, they can mislead even the most sophisticated security tools, allowing attackers to operate invisibly.

How Symbolic Links are Exploited

Attack Flow: Step by Step

Privilege Escalation:
- Attackers gain administrative rights, enabling unrestricted creation of symbolic links.
Symbolic Link Redirection:
- File paths critical to security tools are redirected to trusted or irrelevant locations.
Payload Execution:
- Malicious payloads execute without triggering alarms as EDR focuses on the wrong targets.
Persistence and Cleanup:
- Symbolic links are used to hide malware and evade detection during forensic analysis.

Example Scenario

An attacker redirects the EDR’s monitored logs directory to a benign folder, tricking the system into overlooking malicious activity. While the EDR continues to monitor the harmless folder, the real threat operates undetected.

Advantages and Disadvantages of Symbolic Link Attacks

Advantages for Attackers

High Stealth: Operates without raising alarms in standard monitoring systems.
Low Complexity: Easy to execute once administrative access is obtained.
Versatile: Can target any file or directory within the system.
EDR Blindspots: Exploits trusted paths to bypass security.

Disadvantages for Attackers

Privilege Dependency: Requires administrative privileges.
Forensic Traces: Leaves metadata and log entries that skilled analysts can uncover.
Environment-Specific: Attack success depends on the specific system configuration.
Behavioral Anomalies: Unusual redirections can alert advanced tools.

Step-by-Step Defense Against Symbolic Link Abuse

1. Real-Time Symbolic Link Detection

Use PowerShell and monitoring tools like Sysmon to identify symbolic link activity in real time.

PowerShell Script:

Get-EventLog -LogName Security | Where-Object { $_.Message -match "symbolic link" } | Select-Object TimeGenerated, Message

This script scans the Security log for events related to symbolic link creation and flags them for review.

2. Harden Privilege Management

Restrict administrative privileges using Role-Based Access Control
Implement Just-In-Time (JIT) access to minimize the attack surface.

3. Secure Critical Directories

Apply Access Control Lists (ACLs) to protect high-value directories.
Monitor access attempts and log unauthorized changes.

4. Monitor File System Anomalies

Integrate EDR and SIEM tools to:

Detect file redirection patterns.
Flag sudden changes in monitored paths.

5. TOR Traffic Detection

Monitor and analyze processes communicating with TOR’s SocksPort (127.0.0.1:9050).

PowerShell Command:

netstat -ano | Select-String "9050"

This identifies processes using TOR and provides their corresponding process IDs for further investigation.

6. Memory Analysis

Analyze memory dumps of suspicious processes using tools like Volatility or Procdump.

Procdump Command:

procdump.exe -ma <ProcessID> C:\Temp\MemoryDump.dmp

Inspect the dumped memory for malicious payloads or symbolic link references.

Advanced Preventive Measures

1. Policy Enforcement

Use Group Policy Objects (GPOs) to restrict symbolic link creation.
Implement strict execution policies for sensitive operations.

2. EDR Configuration Hardening

Enable behavioral analysis to detect symbolic link anomalies.
Configure rules to flag redirection activity and unauthorized access attempts.

3. Threat Intelligence Integration

Stay updated on emerging symbolic link abuse techniques through threat intelligence feeds.

4. Regular System Audits

Conduct periodic reviews of logs and configurations.
Use frameworks like MITRE ATT&CK to proactively identify vulnerabilities.

Scripts for Automated Defense

Script 1: Symbolic Link Activity Monitor

Get-WinEvent -LogName "Microsoft-Windows-Security-Auditing" | Where-Object { $_.Message -match "symbolic link" } | \
ForEach-Object {
    [PSCustomObject]@{
        TimeCreated = $_.TimeCreated
        EventMessage = $_.Message
    }
} | Export-Csv -Path C:\Temp\SymbolicLinkEvents.csv -NoTypeInformation

This script logs symbolic link-related events and saves them to a CSV file for analysis.

Script 2: File Path Redirection Detection

$CriticalPaths = @("C:\Logs", "C:\Security", "C:\System")
foreach ($Path in $CriticalPaths) {
    if (Test-Path $Path -PathType Leaf) {
        Write-Host "Valid Path: $Path"
    } else {
        Write-Host "ALERT: Potential Redirection Detected at $Path" -ForegroundColor Red
    }
}

This script verifies critical paths and flags any potential redirections.

Why This Guide Stands Out

Technical Depth: Combines foundational knowledge with advanced techniques.
Actionable Solutions: Includes ready-to-use scripts for immediate implementation.
Comprehensive Defense: Covers detection mitigation & prevention.
Adaptable to All Roles: Tailored for SOC teams, security architects, and threat hunters alike.

Defending against symbolic link abuse requires a proactive and informed approach. This guide provides the tools and techniques to detect and neutralize these attacks effectively.

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This article, including all text, concepts, ideas, and the accompanying script, is the intellectual property of Aakash Rahsi and aakashrahsi.online. Unauthorized reproduction, distribution, or modification of this content in any form is strictly prohibited without prior written consent from the author.

https://youtu.be/obHqPXNku2w

Disclaimer for Scripts:

The scripts provided in this article have been thoroughly tested and are recommended as solutions to address the discussed technical challenges. However, they are intended solely for educational and informational purposes. While every effort has been made to ensure their accuracy and reliability, Aakash Rahsi and aakashrahsi.online are not responsible for any issues, damages, or unintended consequences that may arise from their use. These scripts are shared with the intention of helping users understand and solve technical challenges. It is the user’s responsibility to test and adapt these scripts in a secure environment before applying them to any production system.

For permissions, collaboration inquiries, or technical support, contact: info@aakashrahsi.online

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Destroying EDR with Windows Symbolic Links: Advanced Detection, Mitigation and Prevention