DD-WRT, I Know Where You Live

I’ve always envied CSI’s amazing IP address geolocation capabilities. Not only can they get your exact physical address based solely off your IP (right down to your hotel room number!), it even works on IP addresses that don’t exist!

While that level of IP address tracking is beyond the grasp of us mere mortals, MAC address geolocation provided by Google Location Services and Skyhook is pretty close. Just feed them the MAC address of your wireless router and they will tell you, with scary precision, where you are.

But what if you wanted to find the wireless MAC address of someone else’s router – remotely? Thanks to an information disclosure vulnerability in DD-WRT, you can.

If you are running DD-WRT and have set the ‘info page’ configuration to either ‘enabled’ (the default) or ‘disabled’, an unauthenticated remote attacker can get your:

  • Router’s LAN/WAN/WLAN MAC addresses
  • Router’s internal IP address
  • Internal client’s IP addresses and host names

All they have to do is make a GET request for the ‘/Info.live.htm’ page.

Now, I know what you’re thinking: “Surely this only affects DD-WRT routers that have remote administration enabled!” No, it doesn’t. And don’t call me Shirley.

This is exploitable even with remote administration disabled because DD-WRT is also vulnerable to a public IP DNS rebinding attack. That means that when a user inside your network browses to any Web site, that site can proxy requests through the user’s browser and pull this information from the router’s internal Web interface – no authentication or remote administration required. And, thanks to Rebind, pulling off this type of rebinding attack is pretty simple.

You can read a more detailed write-up on the vulnerability here, or watch the below video demonstrating the use of Rebind and Google Location Services to obtain the location of a DD-WRT router.

Breaking SSL on Embedded Devices

No, this is not some new SSL vulnerability. In fact, it’s a really old vulnerability, as old as cryptography itself: keep your secret keys secret.

A lot of embedded devices provide HTTPS support so that administrators can administer the devices securely over untrusted networks. Some devices, such as SSL VPNs, center their entire functionality around SSL encryption. OK, well SSL isn’t perfect, but it’s still the de facto standard for Web-based encryption. So far, so good.

Here’s where it gets fun: many of these devices use hard-coded SSL keys that are baked into the firmware. That means that if Alice and Bob are both using the same router with the same firmware version, then both of their routers have the same SSL keys. All Eve needs to do in order to decrypt their traffic is to download the firmware from the vendor’s Web site and extract the SSL private key from the firmware image.

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Multiple D-Link Router Vulnerabilities

We have discovered* an authentication bypass vulnerability that affects multiple D-Link routers, specifically those that use PHP based Web interfaces. So far we have confirmed that the following devices are affected:

  • DIR-300
  • DIR-320
  • DIR-615 revD

It appears that the same PHP code was re-used among these routers, so it is likely that other routers are affected as well.

It should be noted that this vulnerability does not only affect those devices that have remote administration enabled. Even with remote administration disabled, this vulnerability can be exploited using a simple hidden image tag in a malicious Web page; as soon as someone behind one of these routers browses to the  malicious page, their browser can be used to re-configure the device.

See our vulnerability report for more detailed information.

* It looks like Karol Celin from Safe Computing found this bug in some of the same routers we did and beat us to the punch! Good to see that others are looking at these devices too! See his BugTraq disclosure here. Our disclosure report further confirms that the DIR-320 and DIR-615 revD devices are also vulnerable.