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Introduction
Red teaming engagements often require stealthy file operations to avoid detection by security tools. Traditional network APIs like socket, connect, and `recv` are heavily monitored, making them risky for malware deployment. This article explores an advanced technique using `NtCreateFile` and `NtDeviceIoControlFile` to interact directly with the AFD driver, reducing detection risks.
Learning Objectives
- Understand how traditional network APIs are monitored by security tools.
- Learn how to leverage Windows system calls (
NtCreateFile,NtDeviceIoControlFile) for stealthy file operations. - Implement a Rust-based proof-of-concept (PoC) to bypass network activity monitoring.
You Should Know
- Bypassing Network Monitoring with Direct AFD Driver Interaction
Command (Rust Implementation):
use winapi::um::winternl::{NtCreateFile, NtDeviceIoControlFile};
use std::ptr;
// Example syscall implementation (simplified)
unsafe {
let status = NtCreateFile(
&mut file_handle,
FILE_READ_DATA,
&object_attributes,
&mut io_status_block,
null_mut(),
0,
FILE_SHARE_READ,
FILE_OPEN,
FILE_SYNCHRONOUS_IO_NONALERT,
null_mut(),
0
);
}
Step-by-Step Guide:
- Objective: Avoid hooks on standard network APIs by using low-level Windows syscalls.
2. Implementation:
- Use `NtCreateFile` to open a handle to the AFD driver (Windows Ancillary Function Driver).
- Use `NtDeviceIoControlFile` to send/receive data directly, bypassing user-mode API monitoring.
- Verification: Debug logs confirm the absence of standard network API calls in process monitoring tools.
2. Rust-Based PoC for Red Teaming
GitHub PoC Link: https://lnkd.in/gHpAy5gu
Key Features:
- Pure Rust implementation for low-level syscall access.
- No dependency on `libc` or Win32 APIs, reducing detection vectors.
- Debug outputs to verify evasion success.
3. Why AFD Driver?
- The AFD driver handles socket operations at the kernel level.
- Direct interaction avoids user-mode hooks placed by EDR/AV solutions.
- Example:
Syscall -> AFD Driver -> TCP/IP Stack
4. Detection Mitigation Techniques
- Obfuscation: Encrypt payloads in transit.
- Timing Delays: Avoid rapid, suspicious network activity.
- Legitimate Traffic Mimicry: Blend exfiltration with normal HTTP/HTTPS traffic.
5. Syscall vs. API: Trade-offs
| Method | Pros | Cons |
|-|–|–|
| Standard APIs | Easy to implement | Highly monitored |
| Direct Syscall| Bypasses user-mode hooks | Complex, requires deep OS knowledge |
6. EDR Evasion Checklist
1. Audit all network-related syscalls in your tool.
2. Test against commercial EDRs (CrowdStrike, SentinelOne).
3. Validate with Sysmon/Procmon for artifacts.
7. Future-Proofing: Kernel-Level Detection
- Threat: EDRs are moving kernel-side (e.g., Falcon Overwatch).
- Solution: Combine syscall evasion with rootkit techniques (e.g., DKOM).
What Undercode Say
- Key Takeaway 1: Direct syscall usage is a powerful but risky evasion method—misuse can crash systems.
- Key Takeaway 2: Red teams must balance stealth with reliability; over-engineering can introduce flaws.
Analysis:
The shift toward kernel-level detection (e.g., Microsoft Kernel-Mode Threat Emulation) means red teams must adapt. While AFD driver interaction works today, long-term success requires continuous research into Windows internals and hardware-assisted virtualization (HVCI) bypasses.
Prediction
As EDRs improve kernel visibility, red teams will increasingly turn to:
– Hardware-based attacks (e.g., Intel CET bypasses).
– Legitimate protocol abuse (e.g., DNS-over-HTTPS for C2).
– AI-assisted evasion (e.g., generative adversarial networks to mimic benign traffic).
For the full Rust PoC, visit Kavin E’s GitHub.
IT/Security Reporter URL:
Reported By: Kavinarasue Redteaming – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
