CVE-2023-52369 is a recently disclosed stack overflow vulnerability in the NFC (Near Field Communication) module of several embedded and IoT devices. This security flaw could allow a remote attacker to crash device services or possibly run malicious code, impacting both the availability and integrity of affected systems. In this post, we’ll break down how the vulnerability works, show relevant code snippets, provide links to further resources, and discuss how attackers might exploit this issue.

Severity: High

A stack overflow happens when more data is written to a buffer located on the stack than what it can actually hold. In this case, a specially crafted NFC message can trigger the overflow, corrupting important information in memory and, potentially, letting attackers control the execution flow of the device.

Where’s the Problem?

This bug lies in the way the NFC message parsing code handles incoming data, especially when checking the size of incoming NFC frames.

Here's a simplified, exclusive look at a vulnerable code section (not vendor-specific but representative):

// Vulnerable NFC frame parsing function
void parse_nfc_frame(uint8_t *data, size_t len) {
    char frame_buffer[128];

    // BAD: No proper length validation!
    memcpy(frame_buffer, data, len);

    // ...process frame_buffer...
}

What’s Wrong?

1. No length checks: The code copies len bytes from user-supplied data into a buffer only 128 bytes big, without checking whether len is greater than 128.
2. If someone sends an NFC frame longer than 128 bytes, important stack data (return addresses, variables) is overwritten.

How Does Exploitation Work?

1. Attack vector: Any scenario where an attacker can send raw NFC frames to the affected device (like bumping a rogue NFC tag, over-the-air, etc.).

Example Exploit (Theoretical Pseudocode)

# This code shows the concept, NOT an actual field-ready exploit.
import nfc

# Construct an NFC message >128 bytes
payload = b"A" * 256

# Use an NFC library (like nfcpy) to send to the device
clf = nfc.ContactlessFrontend('usb')
clf.connect(rdwr={'on-connect': lambda tag: tag.send_cmd(payload)})
print("Oversized NFC frame sent.")

Please note: Actual exploitation depends on hardware, operating system, and memory protection features (like stack canaries or ASLR).

Denial of Service: Crash the NFC service, make the device unresponsive to further NFC actions.

- Service Integrity: Potential for more serious attacks like firmware modification or arbitrary code execution (if additional checks are not in place).
- Attack surface: Any use of NFC—smartphones, payment terminals, ticketing machines, IoT devices, access controls, etc.

Proper bounds checking must be restored, for example

void parse_nfc_frame(uint8_t *data, size_t len) {
    char frame_buffer[128];

    if (len > sizeof(frame_buffer)) {
        // Handle error properly, log and maybe disconnect
        return;
    }

    memcpy(frame_buffer, data, len);
    // ...process frame_buffer...
}

Vendors are patching this by adding size checks or switching to safe copy routines.

References & Resources

- Official NVD Record for CVE-2023-52369
- How Stack Overflows Work (GeeksforGeeks)
- nfcpy Library Docs (Python NFC)

Conclusion

CVE-2023-52369 highlights the ongoing risks of unsafe buffer handling in low-level device modules like NFC. While simple, stack overflows can have devastating impacts—from losing service availability to letting hackers take over. Always keep your devices’ firmware updated, disable unnecessary NFC features, and stay alert for vendor advisories.

Have an IoT or NFC project? Double-check any buffer usage and validate input lengths before copying!


*If you want to know whether your own devices are affected, check with the manufacturer or look at their security advisories for 2023 and 2024 referencing NFC vulnerabilities!*

Timeline

Published on: 02/18/2024 04:15:07 UTC
Last modified on: 12/09/2024 17:33:32 UTC