New Zlob Trojan Alters Your Router Settings

Keep on Guard!


Another new development in the malware arena, this new version of Zlob will actually log onto your router and change the DNS settings to hijack your traffic.

Pretty interesting approach and it will work because 99% of people won’t change the default password on their routers. Let’s face it, have you changed it?

A new Trojan horse masquerading as a video “codec” required to view content on certain Web sites tries to change key settings on the victim’s Internet router so that all of the victim’s Web traffic is routed through servers controlled by the attackers.

According to researchers contacted by Security Fix, recent versions of the ubiquitous “Zlob” Trojan (also known as DNSChanger) will check to see if the victim uses a wireless or wired hardware router. If so, it tries to guess the password needed to administer the router by consulting a built-in list of default router username/password combinations. If successful, the malware alters the victim’s domain name system (DNS) records so that all future traffic passes through the attacker’s network first.

It’s a pretty nifty piece of logic and coding, pretty simple too once you’ve thought of the idea. Just grep the gateway address from the machine (using the correct interface) then try and connect to it with a pre-compiled list of default user names and passwords.

Then bingo you’re in a little insertion of new DNS servers and you’re set!

Relatively few people ever change the default username and password on their wireless routers. I see this often, even among people who have locked down their wireless routers with encryption and all kinds of other security settings: When I confront them about why they haven’t changed the default credentials used to administer the router settings, their rationale is that, ‘Well, why should I change it? An attacker would need to already have a valid connection on my network in order to reach the router administration page, so what’s the difference?’

Obviously, an attack like this illustrates the folly of that reasoning.

Indeed flawed reasoning, you should never leave anything with default passwords if possible as it’s just another weakness waiting to be exploited.

Not to say you will get infected with this malware, because that is unlikely, but someone on your network might…and if you haven’t changed the password the hijack could effect you too (it wouldn’t effect me because my DNS servers are static in my network interface settings as set by me).

Source: Washington Post

Posted in: Hardware Hacking, Malware

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7 Responses to New Zlob Trojan Alters Your Router Settings

  1. the BMX guy June 12, 2008 at 12:06 pm #

    default setups – always fun to see mass production work ;)

  2. moons June 12, 2008 at 4:25 pm #

    Ye, default settings always.

    Just a brief random scan of ips for the router http config page port in where I live in will show loads of results, and sad to say maybe 80% of them are still at default.

    Even recently a neighbour back at hometown who just moved in and got the streamxxx package had the same thing. ISPs maybe should teach their tech staff who does the setup for customers to tell the users to change those passwords.

  3. Navin June 12, 2008 at 7:05 pm #

    point noted moons.that’ll perhaps work in a country like the UK. but where I come from, you consider yourself lucky if you even find a tech personnel who knows how to set up a router!! forget about changing passwords!!

  4. Sleepy June 14, 2008 at 2:23 am #

    After reading this I immediatly went and changed my router password. You were spot on when you said that most of us should know better but still don’t do it. Great article.

  5. Johnny B. June 15, 2008 at 4:32 pm #

    I really appreciate lazy people (or stupid) thanks to them I’ve got free internet :)

    Maybe this will teach them to secure their perimeter (or probably not).

  6. Simon June 16, 2008 at 2:01 am #

    Ive always used a custom router password and login port since I bought my very first router a few years ago. I also use a very long WPA2-PSK security string and MAC address filtering on the wireless connection so I think im pretty secure.

    I can

  7. Sleepy June 23, 2008 at 11:04 pm #

    @Simon
    While it is great that you are security conscious, I’d like to make a few comments here:

    First, WPA2-PSK with a long (over 21 characters) key is great, but the only security I know of for wireless with no known exploit is WPA2 (RADIUS). The “MAC address filtering” is worthless, MAC’s are easily spoofed.

    Your (illegal) intrusion into your neighbors router and your comments about it do confuse me a bit, while there are exploits that can be run and an open router is certainly a big hole to crawl in; your comments don’t really make a lot of sense. I suspect you’re trying to sound as though you know more then you do.

    Either way, I’ll be keeping my router secure, including the password, so hopefully the script kiddies will play somewhere else.