Monday, February 9, 2015

The behavior of the Root login account on Juniper devices

Due to the number of hacks we've been seeing the past few years, I've decided to concentrate a lot of my future blog posts on Security.

It's imperative to secure any device that has an internet connection, whether it's a router, switch, tablet, smartphone, etc.

This was tested on Juniper routers and MXes and I have not tested this on the SRX.

When you first configure your brand new Juniper Device, you are logged into the unit as the user root with no password. Before you can commit your initial config on the device, it will tell you to set the root password for the system.

You do it like this:

[edit system]root@# set root-authentication plain-text-password New Password: type password hereRetype new password: retype password here
The thing you have to worry about is if you decide to enable ssh on the device, the root account is also allowed to ssh into the device.

services {

$ ssh -l root
root@'s password:
--- JUNOS 11.4R7.5 built 2013-03-01 10:14:08 UTC

root@mx80:RE:0% cli

This is dangerous if this device is on the internet. Hackers will always try to brute-force ssh the root login account. I've asked some of my friends/coworkers who know juniper and they did not even know this behavior.

You have to explicitely disable ssh for the root account.

services {
    ssh {
        root-login deny;

Juniper should have built this the opposite way and had root-login defaulted to deny.  So the admin knows that they're actually explicitly allowing users to ssh into the device using the root account.

BTW there is a parameter that says root-login allow.

You might wonder why Juniper did this? Well the reason is probably some engineer early in the software development phase did this for convenience.  Then as the code evolved over the years, you couldn't change the "default" behavior as some customer would complain about this change. So now you're stuck with it.

Small snippet of an attacker trying to gain access via ssh.

Jan 23 05:15:25 localhost sshd[8513]: Invalid user ftp from
Jan 23 05:15:26 localhost sshd[8517]: Invalid user guest from
Jan 23 05:25:17 localhost sshd[8522]: Invalid user root from
Jan 23 05:35:17 localhost sshd[8524]: Invalid user info from
Jan 23 05:45:14 localhost sshd[8526]: Invalid user jack from
Jan 23 05:55:18 localhost sshd[8528]: Invalid user karaf from
Jan 23 06:05:15 localhost sshd[8530]: Invalid user log from
Jan 23 06:25:03 localhost sshd[8786]: Invalid user nagios from
Jan 23 06:34:58 localhost sshd[9071]: Invalid user oracle from
Jan 23 06:44:52 localhost sshd[9307]: Invalid user pi from
Jan 23 06:54:43 localhost sshd[9483]: Invalid user postgres from

Best practice is to deny root-login and setup connection limits and rate limits.

ssh {
root-login deny;
protocol-version v2;
connection-limit 10;
rate-limit 2;

Any device on the internet should also have black-lists and white-lists for SSH to prevent malicious attackers from gaining access to your device.

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