CVE-2022-44804 is a critical buffer overflow vulnerability discovered in the D-Link DIR-882 router firmware versions 1.10B02 and 1.20B06. The root of the issue lies in the websRedirect function of the router's web management interface. Left unpatched, this can let an attacker execute arbitrary code and potentially take over the device.

In this article, you’ll get a simple breakdown of what the vulnerability is, how the exploit works, along with references and code snippets to help better understand the situation.

What is a Buffer Overflow?

A buffer overflow happens when a program writes more data to a buffer than it can handle, which can overwrite nearby memory. On an embedded device like a router, that often means attackers could run their own code (remote code execution, or RCE).

Where’s the Problem? websRedirect

Inside the web interface firmware of the D-Link DIR-882 router, there’s a C function called websRedirect. It takes user input (like a parameter from the URL) and does not properly check the length before copying it into a fixed-size buffer.

When crafted input is sent to this function, it can overflow the buffer, overwriting memory—including critical variables and possibly the return address of the function.

Here’s a simplified pseudocode of what’s going wrong

void websRedirect(webs_t wp, char *url)
{
    char redirUrl[256];
    strcpy(redirUrl, url);  // <-- no length check!
    sendHttpRedirect(wp, redirUrl);
}

If url is longer than 255 characters, the data you send spills outside of redirUrl. Since strcpy does not check how long your input is, it overwrites whatever comes right after that buffer in memory.

Attacker identifies the exposed web management interface.

- Default port: 80/tcp (HTTP).

Router processes the request via the websRedirect function.

4. Malicious input overflows the buffer, overwriting the return address (and possibly other values).

Here’s what a raw exploit attempt might look like with curl

curl "http://192.168..1/cgi-bin/webproc?get.do?url=$(python -c \"print('A'*300)\")"

Replace 192.168..1 with your router’s IP. The "A"*300 generates a string of 300 A's—plenty to overflow a 256-character buffer.

Inside a real-world exploit, those A's might get replaced with shellcode or a payload carefully crafted to control the program’s execution.

Official CVE Record:

CVE-2022-44804

https://supportannouncement.us.dlink.com/announcement/publication.aspx?name=SAP10372

Exploit Proof-of-Concept (Exploit-DB 51554):

https://www.exploit-db.com/exploits/51554

Disclosure write-up:

https://ssd-disclosure.com/ssd-advisory-d-link-dir882-websredirect-buffer-overflow/

Conclusion

CVE-2022-44804 is a textbook example of why bounds-checking matters, especially on devices connected directly to the Internet. A buffer overflow in the D-Link DIR-882’s websRedirect could let an attacker take control of your home or office router. Always keep your firmware up to date and limit remote management where possible.

Timeline

Published on: 11/22/2022 15:15:00 UTC
Last modified on: 11/23/2022 19:53:00 UTC