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DNS Rebinding Attacks, Multi-Pin Variant
Morty writes "DNS rebinding attacks can be used by hostile websites to get browsers to attack behind firewalls, or to attack third parties. Browsers use "pinning" to prevent this, but a paper describes so-called multi-pin vulnerabilities that bypass the existing protections. Note that, from a DNS perspective, this is a "feature" rather than an implementation bug, although it's possible that DNS servers could be modified to prevent external sources from being able to point at internal resources."
Heh, my boy, you just summed up the Web's great affliction in a nutshell.
This particular exploit vector is especially troublesome because turning off the ability to point a name at multiple IPs would break a large part of the Internet. But it wouldn't be an issue for web browsers if we didn't see the need for the Web to be dynamic and interactive. Dynamism and interactivity are really not built into HTTP. It would be more accurate to say that HTTP was designed to be just the opposite.
Website designers and software makers have been trying to turn the Web into a collection of desktop applications since about the time the Web was invented. This runs counter to what Tim Berners Lee intended. HTTP is stateless for a reason. I honestly don't think he made HTTP stateless because he envisioned the havoc that malicious websites could cause, but the principle of agnosticism (i.e. providing content without knowing anything about the requester's capabilities) that's implicit in the protocol is inherently more secure than the desire of many to make websites into remotely-accessed desktop apps.
Unfortunately, this particular horse bolted from the barn in the earliest days of the web, and there's no easy way to get it back in. A wise web developer will nonetheless read and understand the HTTP protocol. Its statelessness and agnosticism can be strengths when considered in the proper light....
...Yeesh, that last sentence makes me feel like Yoda counselling young Luke.... 8^/
Crumb's Corollary: Never bring a knife to a bun fight.
If you haven't read the article, I'll summarize it for you: its another critical vulnerability in java/javascript. The sandboxed script in the web browser alternately makes GET and POST requests the "same" server with each POST containing the contents of the prior GET... Only the IP address associated with the server's hostname keeps alternating between a server inside your firewall and the attacker's real server outside it. Oops.
At times like these, I tell a story about 1988 when I wrote a BBS terminal emulator for the Commodore 64 which cleverly allowed the BBS to send and run new code on the caller's machine. Another gentleman who didn't much like me noticed the feature and arranged for a number of BBS systems to execute the code at location 64738: system reset.
There is no safe way to run complex sandboxed code on a user's PC and no safe way to allow sandboxed code access to the network. Either you trust the source of the program and let it do what it needs to do, or you don't trust it and don't allow it to run on your PC at all. How many of these vulnerabilities are we going to run through before we finally figure that out?
Moderating "-1, Disagree" is simple censorship. Have the guts to post your opinion.
Did you read the abstract?
It's well written, and has lots of examples of exactly how this vulnerability can be exploited. In short, I could probably sit down and in a single afternoon, write a set of scripts for a webserver and DNS server, post it on a $30/month "virtual host" server, and take out an ad for $100, and end up with a powerful DDOS attack on my host of choice.
All done in less than 24 hours.
Screw the "cyber-terrorists" in Russia, this is REALLY BIG, and is one of many REALLY BIG problems that can be exploited! And the fact that we're here, reading and posting here, is demonstration of the fact that the many vulnerabilities of the Internet are NOT being exploited to anything like their real potential...
So think about it: while we here at Slashdork might know as many as a dozen exploitable vulnerabilities like this one that would be nearly impossible to close, how many of us have actually DONE any of these?
And that, folks, is why security will NEVER be 100% technical, and there will always be a social mechanism involved - there really is an amazing amount of security in simply knowing that if you do, really bad stuff could really happen to you.
Not will happen, not even likely to happen. Just could happen is enough.
Besides, there's a funny paradox at work here: those who have the skills to pull off an attack like this also have the skills to earn an income that's legitimate, without all the risks. I'm tempted from time to time to make use of my skills in a bad way when I think about how easy it is for me to wreak havoc - but the risks of doing so have always stopped me far short. I enjoy my day job, since its nature is fundamentally altruistic. So I'm harmless.
As a case in point, I was chatting with my flight instructor and a staff member at the local FBO (an airport for small planes) and the staff member mentioned something about an annoying ex-boyfriend who kept calling her.
Without thinking, I mentioned the possibility of writing a quick script to send him 100,000 text messages that would say "Leave me the freak alone!". I imagined a two-line script that would take all of about 10 seconds to write, and I could use the hotspot at the FBO to do it.
100,000 isn't even a particularly big number for me - I routinely deal with datasets in the millions of records - so it didn't really occur to me right away what a blow that would be. But 100,000 times 5 cents adds up to $5,000 worth of text messages! And I'm sure that his cell company would limit the number of messages to be sent, but it's pretty certain that quite a few WOULD get through.
It was surprising to me what a staggering blow this would be. I was actually a bit embarrassed at having mentioned it.
Don't underestimate the power of social mechanisms to ensure our security!
I have no problem with your religion until you decide it's reason to deprive others of the truth.