Most Home Routers Vulnerable to Flash UPnP Attack

An Anonymous reader noted that some folks at GNU Citizen have been researching UPNP Vulnerabilities in home routers, and have produced a flash swf file capable of opening open ports into your network simply by visiting an unfortunate URL. Looks like Firefox & Safari users are safe for now.

Re:Nothing new, really

[someone1234]

Yes. You may not be sure if a site is malicious or not, without visiting it.
And some sites may become malicious suddenly because of all those syndicated ads around.

Re:Nothing new, really

[Anonymous Coward]

Well yes. If you never visit a site with adverts. Or the Internet as it's otherwise known. Sure, you can block them (and I do) but sometimes sites switch to new providers and you are vulnerable for the time it takes to update the block file.

I'm not really surprised to be honest - I always thought UPnP looked fishy to me so I disabled it on my router. I don't like the idea that anyone coming to visit can plug in their malware-ridden Windows laptop and reconfigure my router. Sure, having it turned off means X-Box Live is less happy but that only decreases the number of people who can call me "fag" on a daily basis. I wonder if Microsoft will update the X-Box Live support page where they say that UPnP doesn't make your network insecure...

I also have Flash disabled by default because it is well known to be insecure and buggy and a delivery system for malware. Most proper web-browsers either let you enable flash on a per-site basis or will allow you to do so with a plug-in and this is really the way to go.

Let me be the first...

[sticks_us]

...in this thread anyway, to recommend the flashblock plugin [mozdev.org].

I installed it a couple of weeks ago, and really enjoy it. Banner ads have all but disappeared, and I don't even really notice (except for faster page loads and cleaner page layouts). If I want to see a YouTube video, that's easily accomplished--just click on the "F" icon in the blocked section of the page.

As an added bonus, I'm protected from all of these recent security breaches we've seen for Flash...aren't I?

Browsers

[JackSpratts]

as usual opera is resistant.

Re:Turn off UPNP

[Z-MaxX]

I thought the recommended steps for setting up a router were:
... D. Turn off UPNP

I guess that is the wise choice. But UPnP is very handy for me because my home machines always get different IPs from my router, so if I want to port-forward BitTorrent ports to me laptop, desktop, etc., I have to go in and change the port-forwarding config on the router every time I get assigned a new IP. Big PITA. But then I discovered how Azureus can use UPnP to automagically forward the ports for me on the fly. It seems to work fine. Too bad it's a security risk.

Re:Turn off UPNP

[yuna49]

BitTorrent users often use uPNP to punch a hole through the router for torrents. Many torrenting "how-tos" specify using uPNP for this purpose, and it's commonly enabled in many BT clients like Azureus and uTorrent. For most of these people, uPNP is a godsend since it eliminates the need to mess around with portforwarding in the router configuration.

Re:Turn off UPNP

[FlashBIOS]

See if your router supports port triggering [wikipedia.org] or look for that feature in your next router. It is a way to automate port forwarding, and would help you in your setup without being the security risk UPnP is.

Re:Nothing new, really

[lordofwhee]

Let's not forget XSS attacks, this is the kind of thing they're perfect for.

Re:DD-WRT?

[jrumney]

If the firmware has UPnP IGD enabled, then your machine is vulnerable to this attack.

The vulnerability is really Flash not restricting what untrusted scripts can do. The router's UPnP IGD profile is working as designed - an application on a machine within the firewall requests that an incoming port be forwarded, so the router does that. This is useful for VoIP, IM, P2P and other applications that need to be contactable from the outside world. Malicious programs that are running on your machine can always initiate outgoing connections, so generally the UPnP IGD is not allowing anything that cannot already be done. In the case of Flash, it is probably blocking most outgoing connections, so UPnP does expand the possibilities for a malicious Flash app to initiate connections with your machine. But unless Flash also allows you to open server sockets, the attacker would also need to find an exploitable service running on your machine.

All this should be detectable by a decent firewall program running on your local machine.

Re:Turn off UPNP

[pipatron]

Configure your DHCP server (your router in this case) to always give the same IP to the machines that you run server software on. It's trivial, really.

Re:My Home router is a Linux NAT Box.

[Anonymous Coward]

The WRT54g can have a serial port hacked into it [rwhitby.net] for configuration. It's a fairly simple job if you have a soldering pencil around. They can also mount a SMB file system on boot [dd-wrt.com] so you can run whatever you want on the device. This filesystem can contain a shell script to be executed, allowing you to set up whatever you'd like to run at boot on the router.

Re:Open WiFi + this = trouble?

[wbren]

Open WiFi access points are a security nightmare regardless of exploits like this, so the same basic advice still holds: open WiFi access points should be isolated from your "trusted" network. Security vulnerabilities aside, open access points are a legal nightmare waiting to happen (child pornography, phishers, DDoS attacks, intrusion, etc.) In other words, avoid them. Regarding your specific question about this UPnP exploit and open APs, the open AP could be potentially used as a phishing goldmine, especially in high-traffic areas. Since the exploit is not limited to port forwarding (in fact almost anything could be done to the router's configuration), users could potentially be tricked into doing all sorts of things (via DNS spoofs, packet manipulation, etc.) The only difference in the case of an open AP is the scope of the damage, as more users will likely connect to an open vs. closed network. Obviously that attack really only makes sense for non-encrypted sites, since this is exactly the type of thing SSL is designed to prevent.

Re:Turn off UPNP

[ookabooka]

Agreed. I'm sure there are even games that support uPnP so when you host a game, the appropriate port is automatically forwarded. IMO, if you keep a tidy computer network with virus scanners on your computers and scan for malware, then it's not much of an issue. It's still better than hooking up your computer directly to the internet and having window's services exposed. You have to compromise the computer before you can use UPnP to allow the attacker in anyways. What's so bad about having a lock thats easy to disable from the inside? It basically comes down to ease of use versus security. I happen to think the benefits of having programs being able to quickly do port forwarding themselves so I don't have to outweigh the possibility that someone can use the same ability to make a trojan work because I feel I am relatively safe (I'm not an idiot and acknowledge nothing is 100% foolproof) against such security breaches.

Re:Turn off UPNP

[morgan_greywolf]

You're right, but many routers do NOT support this feature out-of-the-box, the most notable of these being the WRT54G.

Personally, I just run a standard ISC DHCP daemon on one of my boxes and then configure it to dole out addresses to machines that need 'static' IPs for server functionality. I also have a dynamic port range for other boxes and devices that can change without any adverse effects.

On a Linux machine (currently there are packages for Ubuntu, Debian and Fedora, plus some others), this can be made easy by the use of the gadmintools' ghdpcd [85.214.17.244].

Re:Questions about Wireless Router Security

[Tony Hoyle]

If a flash plugin can make outgoing XML requests it can persuade a upnp server to make your machine wide open, thus completely disabling your firewall. Making those kind of requests sounds like the kind of thing you want Flash to do, so I'd imagine all versions are vulnerable.

There are some ports.. 137,139,445,etc. that you really don't want on the open internet. If the plugin does something like a port forward of 0-65535 to your machine suddenly *every* service on there is wide open to any attack. It'll bypass protections from eg. the default XP firewall as the packets will appear to be coming from the local LAN (the router) rather than the original source.

It's not just flash (although a malicious advert on a page is the most obvious vector for this). Anything that runs on your machine can do it.. I reckon you could craft such an attack in javascript even (XMLHttpRequest with the right code).

Once the ports are open anything that manages to run on your machine can leave itself wide open without having to make telltale outgoing port connections (although it's often said that outgoing connections are the reason upnp is 'not worse' than existing protections, no working trojan would work in that manner, since the target of the outgoing connection would quickly be found and shut down.. OTOH leaving a trojan on your machine listening on your machine waiting for the command to send spam/infect others/distribute child porn/whatever is much more real a thread).

Re:Turn off UPNP

[_.- thimk! -._]

There are a couple of principles you seem to be missing, starting with the idea of relative security. It is possible to make a wireless network 'more secure' than it is, as configured by default out of the box. It does help, in the same way that improving the security on the average home helps. Will it stop someone determined to get in? Very probably not. Can you make it easier for someone to go to the house next door, that has not implemented any of the steps to secure themselves? Yes. As a rule, people are usually lazier than they are determined to get into one specific network. If folks are serious about wanting a secure network, there are all sorts of things they can do. Most of them involve not having a wireless connection, or spending a *lot* more time, money, and effort on it than folks do on the average home network. Having noted that, let's look at your list.

Hidden SSID: One commonly expressed theory behind hiding a SSID is similar to why you lock your car. If your car is locked, it's a less attractive target than one which isn't. Hiding your SSID does make a network a less obvious target than one which is visible. It doesn't impede any serious search for networks by someone knowledgeable, but it will remain hidden to casual view. Is this vaguely inconvenient? Possibly, but then, really, so are locks. Really, I've never been so fond of that analogy.

If you like, I think a better analogy might actually be that hiding your SSID is like planting a bush in your front yard that obscures a direct view of your front door. It doesn't really make your door any more secure, in and of itself, but it might make it less obvious that there's a door there to begin with. Someone simply walking by might not notice it, but someone sitting in their car, watching folks come and go is sure to notice it. It just makes it more likely that a casual passerby might try one of the obvious doors nearby to see if they can get in, rather than trying yours.

MAC Filtering: Similarly, MAC filtering is better than not MAC filtering. The observer can't get on the network unless they spend enough time analyzing active traffic to sift for MAC info. Yes, with the right tools 'enough time' is relative, and not all that long. But, if you're not around using your wireless network when they're doing the analysis, it's difficult to obtain that info, since your MAC isn't being broadcast to begin with. Is it perfect security? Not by any means, but, again, it's a lot easier to get onto a network that's not using it than one which is. Not everyone is running Kismet with a wireless network card configured in promiscuous mode, and even with the number of folks who are, most are more likely to roll a half block down to the completely open network that's almost invariably there than spend time trying to get onto the more secure network, simply for the challenge of it.

Change the default password: If you seriously don't understand this, then you are completely clueless, regardless what tools you're using. Just because you can guess a few passwords using the short list that unimaginative folks commonly use doesn't mean that you can guess any password. (Of course, script kiddies commonly don't have any idea why what they use works, but that doesn't mean it doesn't.) If you were thinking at all about what you were writing, you'd see you make the point yourself as to exactly why it's important. You commonly 'just look up manufacturers default passwords'. If they set a proper password, it makes things more difficult, and you have to try to guess it. With a good password, you're not going to simply guess it.

Crashing the Router: As for your alternative, no decent router should ever come back up with the factory presets after a simple crash. It should always come up with the custom settings, or, failing that, remain hung until manually reset by hand. Even if they do come up with the factory defaults, for modern routers at least, that should be with the external management interface disabled.

Not

Re:Turn off UPNP

[InvisiBill]

WRT54G (Arguably the most prolific consumer grade router in existence) does support static IP assignments via DHCP.

Certain versions, at least, do not. That was the main reason I switched to DD-WRT. The compact version also did not support it last I knew (a friend has this router).

But yes, even the D-Link DI-704 that I purchased in 2000 for $20 (i.e. it was really cheap a really long time ago) did support reserved DHCP, and I'll never again use a router without it. I personally find it unforgivable that Linksys' instructions for port forwarding essentially tell you to completely disable DHCP and just manually configure every device on your network.

Re:My Home router is a Linux NAT Box.

[AMuse]

If you really want to tinker around with Linux as a home NAT/Firewall device, you would love the Soekris [soekris.com] NET4801 [soekris.com] or NET5501 [soekris.com] boxes.

I have one (I have no financial relationship with them other than customer) and I really love it. Very low power, 4GB flash card (up to 8 now I think), 1GB of RAM, no fans, no noise and if I want to I can put a large USB external drive (or small laptop drive inside) to do NFS/SMB/ETC.

All that and the wonder of Linux IPTables, routing, NATting, OpenVPN, OpenSSH for around $300. I replaced an old P3 box I had been using as a router and my power bill thanks me every month. :)

Also, each unit ships with a free pudding!! (Warning: Pudding may be evil.)

Re:Turn off UPNP

[Corporate Troll]

I linked this [wikipedia.org] already elsewhere. It doesn't mention anything about being used for encryption, so I hope you're wrong. (You're not: WPA-PSK uses it in the hash-function of passwords [wikipedia.org].) Still, the SSID is unhideable, since the first link shows it's transmitted in cleartext.

Re:Turn off UPNP

[adolf]

All of us self-respecting geeks realized, years ago, that it was far cheaper, easier, and better to run OpenWRT/DD-WRT/Alchemy on a WRT54G from Wal-Mart, than to maintain yet-another-fucking-PC at home.

It's a good gig: A Linux box with 5 Ethernet ports and a WiFi radio for ~$50.

Having zero moving parts and negligible power consumption is a big help, too.

Re:Turn off UPNP

[RpiMatty]

Just make a couple of .bat files to change your ip address. (I am assuming windows because you said gaming machine).

netsh interface ip set address name="Local Area Connection" static 192.168.101.2 255.255.255.0 192.168.101.1 1

That will set your ip to 192.168.101.2 with a gateway of 192.168.101.1 - Fill in your own home network values.

Here is a 3 line .bat file to set dhcp, renew your address, and pause to show you the results.

netsh interface ip set address "Local Area Connection" dhcp
ipconfig /renew "Local Area Connection"
pause

I have about 6 different batch files in a folder in my Quick Launch toolbar on my WinXP work laptop. It takes 2 clicks for me to change my ip address. If I go to a new site where I need to create a new static ip, I just copy of one the batch files, rename it and put in the new information.

Re:WHERE $money; PUT $mouth

[Anonymous Coward]

Here's the problem. Home routers normally support only WEP and WPA-PSK. WEP is a joke. I have software on my laptop that performs a linear keyspace attack against WEP - that is to say that a 128 bit key (really 104 bits...) only takes twice as long to break as a 64 bit key.It's called a fragmentation attack. WEP is not only dead, it's stinking up the place and needs to be hauled away for public health reasons. This leaves you with WPA-PSK. There's a well understood method for breaking that as well - you use a broadcast deauthenticate attack to kick the workstations off the network, and force them to reauthenticate - than you snag the authentication challenges, and attack them with using a rainbow table. One rainbow table used for this is about 40BG, but that's still reasonable given the cost of external USB hard drives...

Changing the settings is a bit more difficult - but I wouldn't class it as impossible by any stretch of the imagination.