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Archive for March 31st, 2018

Urgent security advisory – MikroTik – upgrade to 6.41.3 if you can change your bridge implementation, ensure SMB and WWW are not WAN accessible

Posted by jpluimers on 2018/03/31

I both understand the [WayBack] Urgent security advisory – MikroTik and the users reluctant to upgrade: Mikrotik has a history of updates breaking existing behaviour and underdocumenting features and release notes.

The attack is over the www or www-ssl services which by default run on port 80 and 443. You can see on which networks they are bound using this example from the terminal:

> ip service print where name=www
Flags: X - disabled, I - invalid 
 #   NAME       PORT ADDRESS                                        CERTIFICATE   
 0   www          80                               
> ip service print where name=www-ssl
Flags: X - disabled, I - invalid 
 #   NAME       PORT ADDRESS                                        CERTIFICATE   
 0   www-ssl     443                               

Note that if your device was infected, not all upgrades will remove the infection on all machines (even though it is mentioned in the FAQ below!). This is one of the “underdocumenting” aspects I mentioned.

There is no way to officially check if your device is infected. If you suspect it is and cannot upgrade to 6.41.3 or more recent, then you need to use [WayBack] Manual:Netinstall – MikroTik Wiki to wipe clean your router and re-install.

Be careful which version you upgrade to:

Somewhere in the middle of page 2 of the above post [WayBack], this is slightly addressed:

1) Upgrade to 6.38.5 fixes the botnet scanner and removes it.
2) Upgrade to 6.41.3 fixes SMB vulnerability.

Later this morning further below on page 2 of the above post [WayBack] it was elaborated more:

I recommend that you re-read all the posts from “normis”. Seems that we are going into circles.

1) Winbox port is used only to find out that this is RouterOS powered device (Winbox is not affected by vulnerabilities that we know of);
2) WWW service (“/ip service”) is used in order to “hack” your router if Firewall did not drop connections to this port (affected service was Webfig which by default is running on port 80, but you can change port under “/ip service” menu and then this other port must be protected). For example, “/ip firewall filter add chain=input action=drop in-interface=WAN connection-state=new”;
3) Issue with SMB is completely another thing but the same rules apply. If device (in this case SMB port) is protected by firewall, then no one can use this issue in order to mess up with your router. Usually attacks come to your router from public Internet (not from LAN) and in normal situation SMB access is not open for public Internet;
4) There is not and will not be an official way to gain access to routers shell.

You will be safe from both of these issues if you upgrade your routers (6.38.5 for WWW issue and 6.41.3 for SMB). In order to upgrade many devices at the same time – you can use MikroTik tool called The Dude or use scripts.

From the above post, at least read the FAQ:


What is affected?

– Webfig with standard port 80 and no firewall rules
– Winbox has nothing to do with the vulnerability, Winbox port is only used by the scanners to identify MikroTik brand devices. Then it proceeds to exploit WEBFIG through port 80.

Am I safe? 

– If you upgraded your router in the last ~12 months, you are safe
– If you had “ip service” “www” disabled: you are safe
– If you had firewall configured for port “80”: you are safe
– If you only had Hotspot in your LAN, but Webfig was not available: you are safe.
– If you only had User Manager in your LAN, but Webfig was not available: you are safe.
– If you had other Winbox port before this: you are safe from the scan, but not from the infection.
– If you had “winbox” disabled, you are safe from the scan, not from the infection.

– If you had “ip service” “allowed-from” set to specific network: you are safe if that network was not infected.
– If you had “Webfig” visible to LAN network, you could be infected by an infected device in your LAN.

How to detect and cure?

– Upgrading to v6.38.5 or newer will remove the bad files, stop the infection and prevent anything similar in the future.
– If you upgrade device and you still see attempts to access Telnet from your network – run Tool/Torch and find out a source of the traffic. It will not be router itself, but another device in local network which also is affected and requires an upgrade.


Posted in Internet, MikroTik, Power User, routers, Security | Leave a Comment »

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