Home and small office routers play a critical role in daily digital life, but many of them ship with serious vulnerabilities. One such issue is CVE-2022-44193, a Buffer Overflow vulnerability discovered in the popular Netgear R700P router (_firmware version V1.3.1.64_). This flaw allows remote attackers to potentially run malicious code on the router by abusing specific HTTP parameters. In this long read, we’ll walk you through the discovery, exploitation, and the risks associated with this vulnerability.

What is CVE-2022-44193?

CVE-2022-44193 is a Buffer Overflow vulnerability in Netgear’s Nighthawk R700P router, specifically in the firmware version V1.3.1.64. The bug resides in the embedded web server—handled by /usr/sbin/httpd—in how it processes certain time-related query parameters. When attackers send specially crafted HTTP requests to the router’s management interface, they can overflow buffers related to the starthour, startminute, endhour, and endminute parameters.

Buffer overflows can have serious consequences: attackers can crash the web interface, or, in the worst cases, execute arbitrary code and gain control over the device.

Technical Analysis

The Netgear R700P offers a web-based admin interface for settings and device management. This service is provided by an httpd process running on the router.

The vulnerability is found in CGI functions that process time frame configuration—such as parental controls or access schedules. Here, user input from 'starthour', 'startminute', 'endhour', and 'endminute' is read into fixed-size buffers without proper length checks.

Let’s look at a simplified version of what happens in the vulnerable code

// Vulnerable logic in /usr/sbin/httpd
char time_frame[8];

// This copies user-supplied data into a buffer without size check!
strcpy(time_frame, get_query_param("starthour"));

The problem? If the attacker sends a value longer than 8 bytes for starthour, it overflows time_frame, potentially corrupting memory.

endminute

Whenever you set up time limits, these fields are processed. The router expects things like starthour=03 or startminute=28, but there’s nothing stopping an attacker from sending longer, malicious strings.

Proof of Concept: Buffer Overflow Exploit

To demonstrate the vulnerability, let’s say you run the following curl command. It sends an overlong string for starthour in a POST request to a schedule configuration endpoint.

curl -v -X POST "http://<router-ip>/cgi-bin/Schedule.cgi"; \
    -d "starthour=AAAAAAAAAAAAAAAAAAAAAAAAAAAAA&startminute=00&endhour=23&endminute=59"

If the router is running the vulnerable firmware, it may crash, reboot, or exhibit erratic behavior depending on how the overflow is handled.

A More Malicious Attempt

An actual attacker might use a payload crafted to overwrite control data in memory, aiming to hijack the router’s execution flow. For example:

curl -X POST "http://<router-ip>/cgi-bin/Schedule.cgi"; \
    -d "starthour=$(python -c 'print("A"*32 + "\xde\xad\xbe\xef")')&startminute=00&endhour=23&endminute=59"


Here, the starthour includes a pattern (\xde\xad\xbe\xef) to cause predictable behavior or, in an advanced scenario, redirect the processor to run malicious shellcode.

Impact

A successful attack provides control over the router’s httpd process. If the process runs with elevated privileges (common on embedded Linux), attackers could:

Use the router as a bot in larger attacks.

All this can be achieved without any authentication if remote administration is enabled or if attackers have local network access—a very real risk for exposed routers.

If you’re using a Netgear R700P or similar model

1. Update Firmware: Always use the latest firmware from Netgear’s official support page. Since this issue is public, newer firmware releases should include a fix.
2. Disable Remote Management: Unless absolutely necessary, turn off remote management to prevent attackers from reaching the web interface from outside your local network.

Use Strong Passwords: Protect the admin interface with a non-default, strong password.

4. Network Segmentation: Isolate untrusted devices and consider moving IoT items to a guest network.

References and Further Reading

- CVE-2022-44193 on NVD
- Original Disclosure (Packet Storm)
- Netgear Security Advisory page
- Firmware downloads for R700P

Conclusion

CVE-2022-44193 highlights the importance of secure coding—especially in devices critical to network safety. A simple missing length check can open the door to devastating attacks. Users and businesses must remain vigilant, apply patches, and configure their routers for maximum security.

If you’re running Netgear R700P on V1.3.1.64, act now—update and protect your network.


Stay secure! If you have further questions about securing your home router, let us know below.

Timeline

Published on: 11/22/2022 14:15:00 UTC
Last modified on: 11/23/2022 18:51:00 UTC