This Week In Security: Zeroconf Strikes Again, Lastpass Leaks Your Last Password, And All Your Data Is Belong To Us

VoIP cameras, DVRs, and other devices running the Web Services Dynamic Discovery (WSDD) protocol are being used in a new type of DDoS attack. This isn’t the first time a zeroconf service has been hijacked as part of a DDoS, as UPnP has also been abused in similar ways.

Feel like alphabet soup yet? A Denial of Service attack is one where the target is simply made unavailable, rather than actually compromised. The classic example of this is the SYN flood, where an attacker would open hundreds of connections to a web server at once, exhausting the server’s resources and interrupting legitimate use of that server. As mitigations for these attacks were developed (SYN Cookies, for example), DoS attacks were replaced by Distributed Denial of Service (DDOS) attacks. Rather than attack a weakness on the target machine, like available RAM or CPU cycles, a DDoS generally targets available network bandwidth by hitting the target website from many, many locations at once. No clever software tricks can help when your Internet connection is fully saturated with junk traffic.

And one way to get many, many computers to send traffic to the same IP is to run a botnet. Your five megabit upload bandwidth might not seem like much, but if a thousand computers are each saturating their 5 megabits, the resulting 5 gigabit attack is nothing to sneeze at. DDoS amplification is when a third party service is used as a part of an attack. Imagine sending a DNS request with a spoofed source IP address. A UDP connection doesn’t have the initial handshake of a TCP packet, so detecting a spoof of this sort is much more difficult. You send a relatively small DNS request, and a DNS server responds by sending a larger reply — not to your IP, but to the target IP that you spoofed. This sort of amplification is usually done as part of a botnet DDoS attack, resulting in even more attack bandwidth. The largest confirmed DDoS attack on record is a staggering 1.3 Terabytes per second, was aimed at Github, and used Memcached as the amplification vector.

Now back to Zeroconf. Zero-configuration networking is the idea that things should “just work” when plugged into a network together. When you have the option to send video to your Chromecast, or Windows shows you the list of all the other devices on your network, you’re seeing zeroconf in action. Zeroconf protocols like UPnP and WSDD are intended to run only over the local network, but vendors are notorious for mis-implementing standards, and here is no exception. WSDD as defined should only respond to multicast requests on UDP port 3702. Many vendors have built their WSDD support in such a way that devices will respond to WSDD requests from any IP address, multicast or not. The last key to this amplification technique is the actual amplification. How small of a packet can an attacker send, vs how big of a packet can this trigger in response. Researchers at Akamai identified an eighteen byte message that triggers a much larger response. They managed a 153x amplification factor, which is terrifying. Thankfully, active attacks are running something more like 10x amplification factors.

Lastpass Reveals Your Last Pass

Sometimes software names and the bugs that affect them are downright uncanny. The Lastpass plugin had an issue where a website could run some clever Javascript and retrieve the last password that Lastpass auto-filled. This worked because the Lastpass plugin uses Javascript on the web pages you visit, watching for password prompts to fill. It was discovered that the JS code of a malicious website could interact with the plugin’s code in unintended ways. Because the Lastpass pop-up could be referenced without calling an initialization function, data was still present from the last time that pop-up was shown. Lastpass fixed the problem in release 4.33.0.

More Data Breaches

This week there were two separate stories about very large data breaches. Though technically, neither is a breach so much as passwordless databases carelessly exposed to the internet. First is the more than 100 medical databases being served on the internet without proper security. So far there seems to be plenty of finger-pointing, but with that many security fails, there is plenty of blame to go around. It’s worth noting that each of those exposed databases is a HIPAA violation, and each carries the potential for a sizable fine.

The second is the records of essentially every citizen of Ecuador. An Elasticsearch instance was misconfigured and publicly accessible. While at first glance, this seemed to be yet another government database exposed to the Internet, there was something strange about this database. There was data from multiple sources. About half of the database was consistent with the idea of a government database, but the rest seemed to come from private entities. The researchers working on this story determined an Ecuadorian company named Novaestrat was hosting the vulnerable database.

The database was secured, and Novaestrat’s website has disappeared. There are still more questions than answers concerning this story. Was this database the combined storage for other data breaches? Regardless, the personal data of millions of Ecuadorians was exposed. Interestingly, Julian Assange was among the people with entries in this Database, as a result of his Ecuadorian asylum.

Both of these databases contained personal information, which is of course unchangeable. Millions of people have been doxxed by carelessness, and short of witness-protection-plan level measures, there is no undo button.

Windows Defender

Using Windows Defender? You might be in for a surprise next time you manually run a scan. Since the update this Tuesday, Windows Defender only scans a handful of files when manually running a quick or full scan. As is often the case, this bug was introduced when another problem was being fixed. If you use Windows Defender and want to run a manual scan, the custom scan does still work correctly.

Memcached Servers Abused For DDoS Attacks

Cloudflare announced recently that they are seeing an increase in amplification attacks using memcached servers, and that this exploit has the potential to be a big problem because memcached is capable of amplifying an attack significantly. This takes DDoS attacks to a new level, but the good news is that the problem is confined to a few thousand misconfigured servers, and the solution is to put the servers behind a tighter firewall and to disable UDP. What’s interesting is how the fundamental workings of the Internet are exploited to create and direct a massive amount of traffic.

We start with a botnet. This is when a bunch of Internet-connected devices are compromised and controlled by a malicious user. This could be a set of specific brand of web camera or printer or computer with unsecured firmware. Once the device is compromised, the malicious user can control the botnet and have it execute code. This code could mine cryptocurrency, upload sensitive data, or create a lot of web traffic directed at a particular server, flooding it with requests and creating a distributed denial of service (DDoS) attack that takes down the server. Since the server can’t distinguish regular traffic from malicious traffic, it can’t filter it out and becomes unresponsive.

This DDoS attack is limited to the size of the botnet’s bandwidth, though. If all the web cameras in the botnet are pounding a server as fast as they can, the botnet has reached its max. The next trick is called an amplification attack, and it exploits UDP. UDP (as opposed to TCP) is like the early post office; you send mail and hope it gets there, and if it doesn’t then oh well. There’s no handshaking between communicating computers. When a device sends a UDP packet to a server, it includes the return address so that the server can send the response back. If the device sends a carefully crafted fake request with a different return address, then the server will send the response to that spoofed return address.

So if the web camera sends a request to Server A and the response is sent to Server B, then Server A is unintentionally attacking Server B. If the request is the same size as the response, then there’s no benefit to this attack. If the request is smaller than the response, and Server A sends Server B a bunch of unrequested data for every request from the camera, then you have a successful amplification attack. In the case of memcached, traffic can be amplified by more than 50,000 times, meaning that a small botnet can have a huge effect.

Memcached is a memory caching system whose primary use is to help large websites by caching data that would otherwise be stored in a database or API, so it really shouldn’t be publicly accessible anyway.  And the solution is to turn off public-facing memcached over UDP, but the larger solution is to think about what things you are making available to the Internet, and how they can be used maliciously.

Printer Vulnerabilites Almost As Bad As IoT

Recently ZDNet and Gizmodo published articles outlining a critical flaw in a large array of personal printers. While the number of printers with this flaw is staggering, the ramifications are even more impressive. Ultimately, any of these printers could have documents sent to them stolen even if the document was only intended to be printed as a hard copy.

Luckily the people responsible for this discovery are white-hat in nature, and the release of this information has been made public so the responsible parties can fix the security flaws. Whether or not the “responsible party” is the manufacturer of the printer, though, is still somewhat unclear because part of the exploit takes advantage of a standard that is part of almost all consumer-grade printers. The standard itself may need to be patched.

Right now, however, it doesn’t seem clear exactly how deep the rabbit hole goes. We all remember the DDoS attack that was caused by Internet of Things devices that were poorly secured, and it seems feasible that networked printers could take some part in a similar botnet if a dedicated user really needed them. At the very least, however, your printed documents might not be secure at all, and you may be seeing a patch for your printer’s firmware in the near future.

 

You Might Not Be Able To Read This

Early today, some party unleashed a massive DDoS attack against Dyn, a major DNS host. This led to a number of websites being completely inaccessible. DNS is the backbone of the Internet. It is the phone book that turns URLs into IP addresses. Without it, the Internet still works, but you won’t be able to find anything.

Over the past few months, security professionals have suggested — in as responsible terms as possible — that something big could happen. In early September [Bruce Schneier] wrote, Someone Is Learning How To Take Down The Internet. The implication of this very general warning is that someone — possibly a state actor, but don’t be too sure about that — was figuring out how to attack one of the core services of the web. The easiest way to effectively ‘turn off the Internet’ for everyone is a Distributed Denial of Service attack against root servers, DNS servers, or some other service that plays a key role in the web.

Dyn is responding well to the attack this morning, and the Internet is safe from attack for the time being. As for who is responsible for the attack, what the goal is, and if this will happen again, no one knows. An attack on this scale is most certainly someone with a very large pocketbook or a state actor (Russia, China, the US, UK, Germany, Israel, or the like) but that’s not a given. It’s also not given the DDoS attacks have stopped. You might not be able to read this, but if you can, it might be a good idea to find a shortwave radio.

How To Become Part Of An IoT Botnet

We should all be familiar with the so-called Internet Of Things, a proliferation of Internet-connected embedded electronics. The opportunities offered to hardware hackers by these technologies have been immense, but we should also be aware of some of the security issues surrounding them.

Recently, the website of the well-known security researcher [Brian Krebs] suffered a DDoS attack. What made this attack different from previous ones wasn’t its severity, but that it had been directed not from botnets of malware-laced Windows PCs but from compromised IoT devices.

One might ask how it could be possible to take control of such low-end embedded hardware, seeing as it would normally be safely behind a firewall, preloaded with its own firmware, and without a clueless human at its terminal to open malware-laden email attachments. The answer is quite shocking but not entirely surprising, and lies in some astonishingly poor security on the part of the devices themselves. An exposé of one such mechanism comes courtesy of [Brian Butterly], who took an unremarkable IP webcam and documented its security flaws.

The camera he examined exposes two services, a web interface and a Telnet port. While from a security perspective their lack of encryption is a concern this should not pose a significant danger when the device is safely on a private network and behind a suitable firewall. The problem comes from its ability to send its pictures over the Internet, for the owner to be able to check their camera from their phone some kind of outside access is required. Expensive cameras use a cloud-based web service for this task, but the cheap ones like the camera being examined simply open a port to the outside world.

If you are familiar with basic firewall set-up, you’ll be used to the idea that open ports are something that should be under control of the firewall owner; if a port has not been specifically opened then it should remain closed. How then can the camera open a port? The answer lies with UPnP, a protocol enabled by default on most home routers that allows a device to request an open port. In simple terms, the camera has an inherently insecure service which it asks the router to expose to the world, and in many cases the router meekly complies without its owner being any the wiser. We suspect that many of you who have not done so already will now be taking a look at your home router to curtail its UPnP activities.

We covered the [Brian Krebs] DDoS story  as it unfolded last week, but we’re sure this is likely to be only the first of many stories in this vein. As manufacturers of appliances struggle to learn that they are no longer in the dumb appliance business they need to start taking their software security very seriously indeed.

Webcam image: Asim18 (Own work) [CC BY-SA 3.0], via Wikimedia Commons.

Distributed Censorship Or Extortion? The IoT Vs Brian Krebs

Now it’s official. The particular website that was hit by a record-breaking distributed denial of service (DDOS) attack that we covered a few days ago was that of white-hat security journalist [Brian Krebs]: Krebs on Security.

During the DDOS attack, his site got 600 Gigabits per second of traffic. It didn’t involve amplification or reflection attacks, but rather a distributed network of zombie domestic appliances: routers, IP webcams, and digital video recorders (DVRs). All they did was create HTTP requests for his site, but there were well in excess of 100,000 of these bots.

In the end, [Krebs’] ISP, Akamai, had to drop him. He was getting pro bono service from them to start with, and while they’ve defended him against DDOS attacks in the past, it was costing them too much to continue in this case. An Akamai exec estimates it would have cost them millions to continue defending, and [Brian] doesn’t blame them. But when Akamai dropped the shields, his hosting provider would get slammed. [Krebs] told Akamai to redirect his domain to localhost and then he went dark.

Continue reading “Distributed Censorship Or Extortion? The IoT Vs Brian Krebs”

Extra-Large Denial Of Service Attack Uses DVRs, Webcams

Brace yourselves. The rest of the media is going to be calling this an “IoT DDOS” and the hype will spin out of control. Hype aside, the facts on the ground make it look like an extremely large distributed denial-of-service attack (DDOS) was just carried out using mostly household appliances (145,607 of them!) rather than grandma’s old Win XP system running on Pentiums.

Slide from <a href="http://slideplayer.org/slide/906693/">this talk</a> by Lisa Plesiutschnig
Replace computers with DVRs. Slide from this talk by Lisa Plesiutschnig

We can argue all day about whether a digital video recorder (DVR) or an IP webcam is an “IoT” device and whether this DDOS attack is the biggest to date or merely among them, but the class of devices exploited certainly are not traditional computers, and this is a big hit. Most of these devices run firmware out of flash, and it’s up to the end user (who is not a sysadmin) to keep it up to date or face the wrath of hackers. And it’s certainly the case that as more Internet-facing devices get deployed, the hacker’s attack surface will grow.

Why did the DDOS network use these particular devices? We’re speculating, but we’d guess it’s a combination of difficult-to-update firmware and user “convenience” features like uPnP. To quote the FBI “The UPnP describes the process when a device remotely connects and communicates on a network automatically without authentication.” You can see how this would be good for both the non-tech-savvy and hostile attackers, right? (Turn off UPnP on your router now.)

We alternate between Jekyll and Hyde on the IoT. On one hand, we love having everything in our own home hooked up to our local WiFi network and running on Python scripts. On the other hand, connecting each and every device up to the broader Internet and keeping it secure would be a system administration headache. Average users want the convenience of the latter without having to pay the setup and know-how costs of the former. Right now, they’re left out in the cold. And their toasters are taking down ISPs.