Posts Tagged ‘worm’

Digital Armageddon

Tuesday, March 31st, 2009

April 1, 2009. The major media outlets are all over this one. Digital Armageddon. The end of computing as we know it. Again. But is it? Should we all just “Chill Out?”

So what happens April 1, 2009? Well, Conficker activates. Well, sort of. It activates the latest revision of its auto-update algorithm, switching the number of domains it can find updates on from 250 per day to 50,000 per day. Conficker, in its current form, isn’t really malicious beyond techniques to prevent detection. In order to become malicious, it will need to download an update to the base code.

There are two methods by which Conficker will update its base code. The first method is to download the code via a connection to one of the 50,000 domains it generates. However, it does not scan all 50,000 domains at once. Instead, it creates a random list of 500 of the 50,000 generated domains and scans them for an update. If no update is found, Conficker sleeps for 24 hours and starts over by generating a new list of 50,000 domains, randomly picking 500, and contacting them for an update. The overall result of this is that it becomes nearly impossible to block all of the generated domains, increasing the likelyhood that an update will get through. On the flip side, this process appears that it would result in a very slow spread of updates. It can easily take days, weeks, or months for a single machine to finally stumble upon a live domain.

The second method is to download the code via a peer-to-peer connection between infected hosts. As I understand it, the peer-to-peer mechanism has been active since revision C of Conficker has been in the wild. This mechanism allows an update to spread from system to system in a very rapid manner. Additionally, based on how the peer-to-peer mechanism works, it appears that blocking it is difficult, at best.

So what is the risk here? Seriously, is my computer destined to become a molten heap of slag, a spam factory, or possibly a zombie soldier in a botnet attack against foreign governments? Is all hope lost? Oh my , are we all going to die!

For the love of all things digital, pull it together! It’s not as bad as it looks! First off all, if you consistently update your machines and keep your anti-virus up to date, chances of you being infected are very low. If you don’t keep up to date, then perhaps you should start. At any rate, fire up a web browser and search for a Conficker scanner. Most of the major anti-virus vendors have one. Make sure you’re familiar with the company you’re downloading the scanner from, though, a large number of scam sites have popped up since Conficker hit the mainstream media.

If you’re a network admin, you have a bigger job. First, I’d recommend any windows machines you are responsible for are patched. Yes, that includes those machines on that private network that is oh-so impossible to get to. Conficker can spread via samba shares and USB keys as well. Next, try scanning your network for infections. There are a number of Conficker scanners out there now thanks to the Honeynet Project and Dan Kaminsky. I have personally used both the proof-of-concept python scanner, as well as the latest version of nmap.

If you’re using nmap, the following command line works quite well and is incredibly fast :

nmap -sC –script=smb-check-vulns –script-args=safe=1 -p139,445 \
-d -PN -n -T4 –min-hostgroup 256 –min-parallelism 64 \
-oA conficker_scan

Finally, as a network admin, you should probably have some sort of Intrusion Detection System (IDS) in place. Snort is an open source IDS that works quite well and has a large community following. IDS signatures exist to detect all known variants of Conficker.

So calm down, take a deep breath, and don’t worry. I find it extremely unlikely that April 1 will result in anything more than a blip in network activity. Instead, concentrate on detection and patching. Conficker isn’t Skynet…. Yet.

 

Microsoft wants to infect your computer?!?

Friday, February 15th, 2008

There’s an article over at New Scientist about a “new” technique Microsoft is looking at for delivering patches.  Researchers are looking into distributing patches through a network similar to that of a worm.  These ‘friendly’ worms would use advanced strategies to identify and ‘infect’ computers on a network, and then install the appropriate patches into that system.

On one hand, this looks like it may be a good idea.  In theory, it reduces load on update servers, and it may help to patch computers that would otherwise go un-patched.  Microsoft claims that this technique would spread patches faster and reduce overall network load.

Back in 2003, the now infamous Blaster worm was released.  Blaster took advantage of a buffer overflow in Microsoft’s implementation of RPC.  Once infected, the computer was set to perform a SYN flood attack against Microsoft’s update site, windowsupdate.com.

Shortly after the release of Blaster, a different sort of worm was released, Welchia.  Welchia, like Blaster, took advantage of the RPC bug.  Unlike blaster, however, Welchia attempted to patch the host computer with a series of Microsoft patches.  It would also attempt to remove the Blaster work, if it existed.  Finally, the worm removed itself after 120 days, or January 1, 2004.

Unfortunately, the overall effect of Welchia was negative.  It created a large amount of network traffic by spreading to other machines, and downloading the patches from Microsoft.

The Welchia worm is a good example of what can happen, even when the creator has good intentions.  So, will Microsoft’s attempts be more successful?  Can Microsoft build a bullet-proof worm-like mechanism for spreading patches?  And what about the legality aspect?

In order to spread patches this way, there needs to be some entry point into the remote computer system.  This means a server of some sort must be running on the remote computer.  Is this something we want every Windows machine on the planet running?  A single exploit puts us back into the same boat we’ve been in for a long time.  And Microsoft doesn’t have the best security track record.

Assuming for a moment, however, that Microsoft can develop some sort of secure server, how are the patches delivered?  Obviously a patch-worm is released, likely from Microsoft’s own servers, and spreads to other machines on the Internet.  But, many users have firewalls or NAT devices between themselves and the Internet.  Unless those devices are specifically configured to allow the traffic, the patch-worm will be stopped in it’s tracks.  Corporate firewalls would block this as well.  And what about the bandwidth required to download these patches?  Especially when we’re talking about big patches like service packs.

If the patch-worm somehow makes it to a remote computer, what validation is done to ensure it’s authenticity?  Certificates are useful, but they have been taken advantage of in the past.  If someone with malicious intent can hijack a valid session, there’s no telling what kind of damage can be done.

How will the user be notified about the patch?  Are we talking about auto-install?  Will warning boxes pop up?  What happens when the system needs to be rebooted?

And finally, what about the legal aspects of this?  Releasing worms on the Internet is illegal, and punishable with jail time.  But if that worm is “helpful”, then do the same rules apply?  Network traffic still increases, computer resources are used, and interruptions in service may occur as a result.

 

All I can say is this: This is *my* computer, keep your grubby mitts off it.