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Introduction:
A critical vulnerability, designated CVE-2025-9709, has been disclosed in the widely used Nordic Semiconductor nRF52810 system-on-chip (SoC). This flaw allows attackers to bypass the chip’s hardware-based read-back protection (APPROTECT) via electromagnetic fault injection (EMFI), potentially granting them full access to the device’s firmware and stored secrets. This vulnerability threatens the security of countless IoT devices, from smart home gadgets to medical wearables, underscoring a fundamental hardware security challenge.
Learning Objectives:
- Understand the mechanism of the APPROTECT bypass via Electromagnetic Fault Injection (EMFI).
- Learn how to identify and inventory vulnerable devices within an enterprise network.
- Implement mitigation strategies to protect vulnerable hardware until patches are available.
You Should Know:
1. Identifying Vulnerable Hardware in Your Network
The first step in managing this threat is asset identification. Many devices use Nordic chipsets without explicitly advertising it. Scanning for Bluetooth Low Energy (BLE) services can be a strong indicator.
Command:
`sudo hcitool lescan`
Step‑by‑step guide:
- Ensure Bluetooth is enabled on your Linux scanning machine.
- Open a terminal and run the command
sudo hcitool lescan. This will initiate a scan for nearby BLE devices. - The output will list MAC addresses and device names. Many Nordic-based devices will have names or MAC address OUIs associated with Nordic Semiconductor. Correlate these findings with your asset inventory.
2. Interrogating BLE Services for Chipset Identification
Once a potential target is identified, you can interrogate it to list its available services, which can further fingerprint the chipset.
Command (using `gatttool`):
`gatttool -b –primary`
Step‑by‑step guide:
1. Install `bluez` utils: `sudo apt-get install bluez`
- Run `sudo hcitool lescan` to get the target device’s MAC address.
- Use the command `gatttool -b XX:XX:XX:XX:XX:XX –primary` (replace with the actual MAC).
- Review the list of Universal Unique Identifiers (UUIDs). Nordic-specific services often use a base UUID of
6E40XXXX-B5A3-F393-E0A9-E50E24DCCA9E.
3. Dumping Firmware from a Vulnerable Chip (Post-Exploitation)
This command demonstrates how an attacker would use the `nrfjprog` utility to read out firmware once the APPROTECT bit has been glitched. Understanding this process is crucial for defense.
Command:
`nrfjprog –readcode –family NRF52 -f J-Link firmware_dump.hex`
Step‑by‑step guide:
- An attacker would physically connect a J-Link debugger to the chip’s Serial Wire Debug (SWD) pins.
- After successfully executing the EMFI glitch to disable APPROTECT, the chip’s memory becomes readable.
- Using the Nordic Command Line Tools, the attacker runs the command above. The `–readcode` flag instructs the tool to read the entire code memory, `–family NRF52` specifies the chip family, and `-f J-Link` defines the debugger type. The output is saved to
firmware_dump.hex. - This dumped firmware can then be reverse-engineered to extract cryptographic keys, proprietary algorithms, or other sensitive data.
4. Verifying APPROTECT Status for Forensic Analysis
If you have physical access to a device for security testing, you can check the status of the APPROTECT register to see if it’s already been compromised or is improperly configured.
Command:
`nrfjprog –readuicr –family NRF52`
Step‑by‑step guide:
- Connect a J-Link debugger to the device’s SWD port.
2. Run the command `nrfjprog –readuicr –family NRF52`.
- The output will display the User Information Configuration Registers (UICR). Look for the APPROTECT register value. A value of `0xFFFFFF00` typically indicates it is enabled (secure), while `0xFFFFFFFE` means it is disabled (bypassed). Finding it disabled on a new device could indicate a prior compromise.
5. Windows PowerShell: Network Discovery for IoT Segments
Isolating IoT devices is a key mitigation. This PowerShell script helps discover active hosts on a specific subnet, aiding in network segmentation efforts.
Command (PowerShell):
`1..254 | ForEach-Object {Test-Connection -ComputerName “192.168.1.$_” -Count 1 -Quiet -TimeoutSeconds 1}`
Step‑by‑step guide:
1. Open Windows PowerShell with administrative privileges.
- Modify the IP range (
192.168.1.) to match your network’s subnet. - Execute the command. It will ping each IP from 1 to 254 in the subnet.
- The command returns `True` for responsive hosts. Combine this with ARP table checks (
arp -a) to build a list of all devices on the network segment for further analysis and segmentation.
6. Mitigating with Network Segmentation via Windows Firewall
Once identified, vulnerable devices should be placed in a tightly controlled network segment. This command creates a new firewall rule to block all traffic to a specific subnet.
Command (Windows Command Prompt as Admin):
`netsh advfirewall firewall add rule name=”Block IoT Segment” dir=in action=block remoteip=192.168.50.0/24`
Step‑by‑step guide:
- Identify the subnet you wish to isolate (e.g.,
192.168.50.0/24).
2. Open Command Prompt as Administrator.
- Run the `netsh` command provided. `name` defines the rule name, `dir=in` blocks incoming traffic from that subnet, `action=block` defines the action, and `remoteip` specifies the target subnet.
- Verify the rule is active with
netsh advfirewall firewall show rule name="Block IoT Segment".
7. Linux iptables Rule for IoT Device Quarantine
On a Linux-based gateway or firewall, use iptables to drop all traffic to and from the VLAN containing the vulnerable devices.
Command:
`iptables -A FORWARD -s 192.168.50.0/24 -j DROP && iptables -A FORWARD -d 192.168.50.0/24 -j DROP`
Step‑by‑step guide:
1. Access your Linux firewall/router.
- Determine the IP range of the vulnerable IoT devices (e.g.,
192.168.50.0/24). - The first command appends (
-A) a rule to the `FORWARD` chain to drop all packets originating (-s) from the IoT subnet. The second command drops all packets destined (-d) for that subnet. - Make the rules persistent based on your Linux distribution’s method (e.g., `iptables-save` for some systems).
What Undercode Say:
- Hardware is the New Software: The attack surface has moved down the stack. Software patching is useless against a hardware-level glitch, forcing a radical rethink of IoT security lifecycles.
- The Supply Chain is the Weakest Link: Most companies deploying these chips are not hardware manufacturers. They rely on vendors, creating a complex and opaque supply chain where vulnerability information is slow to propagate and mitigate.
- This vulnerability is not a one-off. It is a class of vulnerability affecting hardware-level security mechanisms in microcontrollers from various vendors. EMFI and other physical attack techniques are becoming more accessible, moving from state-sponsored actors to the broader offensive security community. Defenders must assume physical access is a valid threat model for critical IoT infrastructure and implement cryptographic protections that remain secure even if the hardware is fully extracted and read out.
Prediction:
The successful exploitation of CVE-2025-9709 will catalyze a wave of reverse engineering focused on other microcontroller units (MCUs). Security researchers and threat actors will aggressively apply EMFI and similar techniques (e.g., laser fault injection) to chips from other major vendors, leading to the discovery of similar APPROTECT and secure boot bypasses throughout 2025 and 2026. This will create a sustained period of vulnerability for the embedded and IoT industry, forcing a rapid evolution towards more robust, glitch-resistant hardware security designs and a greater reliance on software-based cryptographic protections that do not trust the underlying hardware.
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IT/Security Reporter URL:
Reported By: Robbe Van – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
