Full Report
In part 1 of this series, we set up the NanoPi R1S as a USB attack tool, covering OS installation, installation of P4wnP1, and even keylogging a “passed through” keyboard. In this part, I am going to focus on operations as an Ethernet attack tool, using two scenarios. Firstly, as a box which can be connected to an unused Ethernet port, and provide remote access to the target’s network, and secondly, as an Ethernet Person in the Middle (PitM), where it can be placed in between a legitimate device and its upstream switch, and mask its own traffic using the legitimate device’s IP address and MAC address. In the second scenario, we can also defeat Network Access Control measures, because the legitimate device will handle all of that.
Analysis Summary
# Tool/Technique: P4wnP1 (Contextual Mention)
## Overview
P4wnP1 is a framework/tool mentioned in the context of setting up the NanoPi R1S device for attack operations. In Part 1 of the series, it was installed to enable USB attack capabilities (like keylogging). In Part 2, the focus shifts to Ethernet operations, implying P4wnP1 serves as the underlying operating environment or primary attack framework on the R1S hosting the Ethernet attack scenarios.
## Technical Details
- Type: Tool / Framework (Implied)
- Platform: NanoPi R1S (Implied Linux distribution, running services like `systemd-network` and `NetworkManager`)
- Capabilities: Facilitates initial setup for USB attack tools (keylogging documented in Part 1) and provides the base for subsequent Ethernet attack scenarios (Remote Access/PitM).
- First Seen: Not specified in the text, but linked to the context of the hardware/framework setup.
## MITRE ATT&CK Mapping
The direct use of P4wnP1 is not detailed in the Ethernet scenarios, but its purpose as an initial access/command and control tool suggests:
- TA0001 - Initial Access / TA0011 - Command and Control
- T1595.002 - Client & Server (If used for C2 establishment)
- T1190 - Exploit Public-Facing Application (If used to stage initial access mechanisms)
## Functionality
### Core Capabilities
- Provides a functional environment on the NanoPi R1S for executing security testing payloads.
- Configuration management for network interfaces (via scripts interacting with `systemd-network` and `NetworkManager`).
### Advanced Features
- Integration with USB attack vectors (keylogging mentioned).
- Facilitates setup for sophisticated network maneuvers (Ethernet PitM).
## Indicators of Compromise
- **File Hashes**: N/A (Specific hashes for P4wnP1 installation/usage are not provided.)
- **File Names**: N/A
- **Registry Keys**: N/A
- **Network Indicators**: N/A
- **Behavioral Indicators**: N/A
## Associated Threat Actors
- Red Teams / Penetration Testers (Context indicated by "Red Team Dropbox").
## Detection Methods
- Detection would likely focus on the presence of the P4wnP1 framework on the device, or unusual network activity generated by the R1S setup itself.
## Mitigation Strategies
- Strict physical security controls to prevent unauthorized hardware introduction (like the NanoPi R1S).
- Monitoring for unknown devices connected to unused Ethernet ports or attempting unauthorized network activity.
## Related Tools/Techniques
- Hardware related setups (NanoPi R1S - repurposed IoT/SBC).
- Network configuration tools (`nmtui`, `nmcli`, `systemd-network`).
---
# Tool/Technique: Ethernet Person in the Middle (PitM) via NanoPi R1S
## Overview
A technique executed using the modified NanoPi R1S device where it is physically placed between a legitimate target device and its upstream switch. The primary goal is to intercept, monitor, and potentially manipulate network traffic while blending in by using the legitimate device's verified MAC and IP addresses, and actively defeating Network Access Control (NAC) systems.
## Technical Details
- Type: Technique
- Platform: Target Ethernet Network (Implied IPv4/Ethernet)
- Capabilities: Traffic interception, MAC/IP address masking, NAC bypass, network monitoring (Wireshark/tcpdump), remote management via SSH tunneling over virtual interfaces.
- First Seen: N/A (General technique, implementation dated July 2020 based on publication).
## MITRE ATT&CK Mapping
- TA0008 - Lateral Movement / TA0006 - Credential Access / TA0007 - Discovery
- T1090 - Proxy
- T1090.003 - Multi-hop Proxy (Implied by using the device to pivot)
- T1557.001 - Man-in-the-Middle: ARP Spoofing (Implied method of achieving PitM on the local segment, though not explicitly named)
- T1049 - Network Sniffing (For traffic capture via `tcpdump`/Wireshark)
## Functionality
### Core Capabilities
- **Traffic Masking**: The R1S masks its own traffic using the legitimate device's IP address and MAC address.
- **NAC Defeat**: Relies on the legitimate device handling all required authentication processes for the connection to the switch.
- **Network Exploration**: Allows the operator to explore the network segment stealthily.
### Advanced Features
- **Network Namespaces**: Utilized to isolate Ethernet interfaces, enhancing configuration control.
- **Virtual Interface Bridging**: Creates virtual interfaces (e.g., `169.254.20.1` and `169.254.20.2`) to route traffic between the isolated namespace and the host system/control channel.
- **Remote Monitoring**: Facilitates piping `tcpdump` traffic over an SSH tunnel directly to a local Wireshark instance (`ssh pitm tcpdump -nli pitm -w - | wireshark -k -i -`).
- **MACsec Resilience**: MACsec traffic passing across the `pitm` bridge does not break functionality, although a reference to `SilentBridge` suggests an alternative is needed if explicit MACsec evasion is required.
## Indicators of Compromise
- **File Hashes**: N/A
- **File Names**: `iptraf` (Used for monitoring), `tcpdump`, `Wireshark`
- **Registry Keys**: N/A
- **Network Indicators**: Normal network traffic associated with the legitimate device whose MAC/IP is being spoofed/masked. Unusual DHCP parameters unique to Linux clients on a non-Linux network might serve as potential indicators.
- **Behavioral Indicators**: Traffic generation suspicious of the **victim/masked device** (e.g., DNS lookups for `armbian.org` when the victim is known to be Windows).
## Associated Threat Actors
- Red Teams / Penetration Testers.
## Detection Methods
- **Traffic Analysis**: Look for anomalous traffic patterns or duplicate MAC/IP advertisements that might indicate a bridging or spoofing mechanism if not perfectly masked.
- **Device Profiling**: Detection of unexpected DHCP identification parameters coming from a device profile (e.g., a Windows machine suddenly presenting Linux-centric DHCP options).
- **Monitoring Disabled Ports**: Auditing ports showing link status but zero legitimate activity from the associated endpoint.
## Mitigation Strategies
- **Network Access Control (NAC)**: Robust NAC solutions that rigidly enforce dynamic binding of MAC/IP addresses upon connection, combined with continuous monitoring.
- **MACsec Configuration**: If 802.1x with MACsec is used, standard ARP-based PitM methods may fail (though the article implies the bridge layer traffic may still pass).
- **Physical Security**: Controlling physical access points to network jacks.
- **Traffic Baseline Analysis**: Establishing baselines for network communication patterns (e.g., known DNS lookups, NTP synchronization) for individual devices to spot anomalies generated by the proxy.
## Related Tools/Techniques
- SilentBridge (Suggested alternative for MACsec environments).
- SSH Port Forwarding (Used for remote management and monitoring).
- Gabriel Ryan’s work on `SilentBridge`.