security hole on local ISP

[Cilia Pretel Gallo <cpretelgallo () yahoo com>]

I've recently discovered a security hole on the modems (which double as routers) used by a Colombian ISP - ETB.

It so happens that all incoming connections to an IP address on said ISP on port 23 or port 80 land on the modem 
instead of the computer(s) connected to it. Even if one tries to redirect those ports to a local machine, the modem 
still gets all the connections on those ports.
Also, connections on ports 23 and 80, from any IP address, will access the modem configuration options. Last year that 
could be done only from private IP addresses (i.e. 192.168.0/24), but now it can be done, as I said, from anywhere. 
I've been told that a few lucky users were able to forward port 80, but in that case, it's port 8080 that is 
intercepted by the modem.
The end result is that anyone, from anywhere, can access the modem of anyone on ETB to mess up their configuration 
(e.g. obtaining and changing the client's username and password, permanently disconnecting them from the internet, and 
so on) - that is, if they have the administration password. Unfortunately, ETB uses the same login/password on all of 
their modems since 2006, which are publicly available on the web.
Login: Administrator
Password: soporteETB2006

The whole IP range 190.24/14 corresponds to ETB clients. Any IP on that range where ports 80 and 23 are open is most 
likely a wide open ETB modem.

Apparently, this issue has been repeatedly reported to ETB, but it always falls on deaf ears. They seem to think this 
is no big deal since nobody knows the username and password for the modems - which is not the case, and even if it 
were, they would be easily crackable by brute force.

Peace,

-Cilia



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