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'I'm Admin. You're Admin. Everyone is Admin.' Remote Access Bug Turns Western Digital My Cloud Into Everyone's Cloud (theregister.co.uk)
Researchers at infosec shop Securify revealed this week a vulnerability, designated CVE-2018-17153, which allows an unauthenticated attacker with network access to the device to bypass password checks and login with admin privileges. From a report:This would, in turn, give the attacker full control over the NAS device, including the ability to view and copy all stored data as well as overwrite and erase contents. If the box is accessible from the public internet, it could be remotely pwned, it appears. Alternatively, malware on a PC on the local network could search for and find a vulnerable My Cloud machine, and compromise it. According to Securify, the flaw itself lies in the way My Cloud creates admin sessions that are attached to an IP address. When an attacker sends a command to the device's web interface, as an HTTP CGI request, they can also include the cookie username=admin -- which unlocks admin access. Thus if properly constructed, the request would establish an admin login session to the device without ever asking for a password. In other words, just tell it you're the admin user in the cookie, and you're in. The researcher told TechCrunch that he reported the vulnerability to Western Digital last year, but the company "stopped responding."
First up--
There are at least 3 kinds of MyCloud out there, not counting the multi-bay devices, which are probably likewise vunerable-- stay with me.
First are the two generations of mycloud "personal cloud" devices. The last is the "Mycloud Home" device, which is more of a personal media server than an actual NAS. Of the first two, the generation 1 is possibly fixable by the end user easily. It uses a REAL root file system on persistent storage, meaning you can go in and make changes to the web UI and pals if you want to. The second generation, however, is a real bitch. I will wax philosophical on this latter model, as the multi-bay devices (EX2, EX2 ultra, and pals) are likewise afflicted, and based on the same codebase. In fact, you can poke at a system identification value, and enable features on the single bay units that are selling points on the more expensive dual bay versions, because they run the exact same software.
The gen 2 MyCloud uses an initial ramdisk backed root file system, into which a cramfs container is mounted by the init script. The web UI and pals are hosted by this cramfs container, so unless you want to bake a brand new container to fix the CVE, you are boned.
Also, the single bay mycloud units are now End of Life, as WD is no longer making them. They have switched whole hog to the MyCloud Home device, which is not a NAS appliance at all.
Now, why I really dont give a flying rat's ass about the CVE:
The MyCloud units DO NOT perform any signature checking against the kernel and ramdisk that the bootloader starts.
SO-- You can TOTALLY replace that epic clusterfuck WD put on it, and replace it with a completely sane and sanitary minimalist debian installation, which lacks a web GUI to attack in the first place.
Gen2 (and similar units) use uBoot. There are lots of good tools for making uBoot images and ramdisks. This system is easily made full-custom.
Hey. Your friendly neighbour hacker here. I've noticed that you have terrible taste when it comes to porn so I've uploaded a few gig of some good stuff to your drive. You're welcome.
... large scale n00bie-style f*ckups by professional companies in the data-security field absolutely bedazzling. Isn't something of this type gross neglect or something and can't they be sued into next wednesday for it?
This is un-fucking-believable.
We suffer more in our imagination than in reality. - Seneca
If your computer can access it then it is "on the network", so unless you plan on disconnecting your computer NIC, connecting the cable to the NAS, accessing your data, unplugging the NAS, clearing your cache and rebooting your system, then reconnecting your NIC every time, you are not following your own advice. Nice try at sounding like you are a security expert, but you made it pretty clear that you don't understand how networks work.
Guns don't kill people; Physics kills people! - John Lithgow as Dick Solomon on Third Rock From The Sun
When will computers be subject to mandatory recalls when they have bugs that effectively prevent them from being used "as designed" or "as marketed?"
Manufacturers would have a choice: Fix the problem or refund the purchase price.
Knowledge is how to play a game, intelligence is how to win, wisdom is knowing what game to play.
Indeed. This CVE has been known about, and known by WD for at least 2 firmware updates.
WD seems staunchly unwilling to fix it. For whatever reason.
Personally I find the software that runs on the MyCloud units to be... Sub-par on a wide assortment of levels, and have gone full custom debian some time ago. The device is MUCH more responsive without running ufraw-batch all the fucking time, and without a huge chunk of memory getting gobbled up by the ramdisk or WD's proprietary indexing daemon.
I also get the benefits of a much more modern kernel (really, these things run a 3.x kernel! Blech!) with zram support (so the disk can actually go to fucking sleep, and not wake up when there is a paging operation).
Sure, it requires you to know how to manage a linux server--- but the benefits! :P
The Gen2's hardware is really not that bad for something the size of a small book, and which uses very little electricity. It can do a surprising number of tasks.
(~1ghz dual core ARMv7 processor, 512mb RAM, gigabit wired ethernet, USB2 port-- for those interested)
Though the manufacturing companies are pandering to the lazy users. The proper way to access a device on your LAN from the Internet is to set up your router with a VPN server. When you're away from home, you connect to your home router via the VPN. That'll give you access to your NAS, your security cameras, your media library, etc. while you're away from home.
But users are too lazy to bother to set up a VPN server (even though many routers now come with one built-in) and manage a dynamic DNS domain name. So manufacturers pander to them by setting up each individual device to be accessible from the cloud. Usually by having the device contact a server via the manufacturer's website, which acts as a go-between for the handshaking between the cloud device when you try to access it from the Internet. That is, the device handles the VPN-like encryption and their server handles tracking your LAN's public IP address (equivalent to dynamic DNS).
By itself this isn't any worse than using a VPN. But multiply it by a half dozen cloud devices, and the chances that every single one of those devices is secure is substantially lower than the chance that your VPN server is secure.
If I didn't know better, I might come to the conclusion that storing sensitive data on someone else's hard drive, at random, was a risk and a bad idea.