|By Lori MacVittie||
|May 1, 2014 09:00 AM EDT||
This week's "bad news" with respect to information security centers on Facebook and the exploitation of HTTP caches to affect a DDoS attack. Reported as a 'vulnerability', this exploit takes advantage of the way the application protocol is designed to work. In fact, the same author who reports the Facebook 'vulnerability' has also shown you can use Google to do the same thing. Just about any site that enables you to submit content containing links and then retrieves those links for you (for caching purposes) could be used in this way. It's not unique to Facebook or Google, for that matter, they just have the perfect environment to make such an exploit highly effective.
The exploit works by using a site (in this case Facebook) to load content and takes advantage of the general principle of amplification to effectively DDoS a third-party site. This is a flood-based like attack, meaning it's attempting to overwhelm a server by flooding it with requests that voraciously consume server-side resources and slow everyone down - to the point of forcing it to appear "down" to legitimate users.
The requests brokered by Facebook are themselves 110% legitimate requests. The requests for an image (or PDF or large video file) are well-formed, and nothing about the requests on an individual basis could be detected as being an attack. This is, in part, why the exploit works: because the individual requests are wholly legitimate requests.
How it Works
The trigger for the "attack" is the caching service. Caches are generally excellent at, well, caching static objects with well-defined URIs. A cache doesn't have a problem finding /myimage.png. It's either there, or it's not and the cache has to go to origin to retrieve it. Where things get more difficult is when requests for content are dynamic; that is, they send parameters that the origin server interprets to determine which image to send, e.g. /myimage?id=30. This is much like an old developer trick to force the reload of dynamic content when browser or server caches indicate a match on the URL. By tacking on a random query parameter, you can "trick" the browser and the server into believing it's a brand new object, and it will go to origin to retrieve it - even though the query parameter is never used. That's where the exploit comes in.
HTTP servers accept as part of the definition of a URI any number of variable query parameters. Those parameters can be ignored or used at the discretion of the application. But when the HTTP server is looking to see if that content has been served already, it does look at those parameters. The reference for a given object is its URL, and thus tacking on a query parameter forces (or tricks if you prefer) the HTTP server to believe the object has never been served before and thus can't be retrieved from a cache.
Caches act on the same principles as an HTTP server because when you get down to brass tacks, a cache is a very specialized HTTP server, focused on mirroring content so it's closer to the user.
<img src=http://target.com/file?r=1> <img src=http://target.com/file?r=2> <img src=http://target.com/file?r=3> ... <img src=http://target.com/file?r=1000>
Many, many, many, many (repeat as necessary) web applications are built using such models. Whether to retrieve text-based content or images is irrelevant to the cache. The cache looks at the request and, if it can't match it somehow, it's going to go to origin.
Which is what's possible with Facebook Notes and Google. By taking advantage of (exploiting) this design principle, if a note crafted with multiple image objects retrieved via a dynamic query is viewed by enough users at the same time, the origin can become overwhelmed or its network oversubscribed.
This is what makes it an exploit, not a vulnerability. There's nothing wrong with the behavior of these caches - they are working exactly as they were designed to act with respect to HTTP. The problem is that when the protocol and caching behavior was defined, such abusive behavior was not considered.
In other words, this is a protocol exploit not specific to Facebook (or Google). In fact, similar exploits have been used to launch attacks in the past. For example, consider some noise raised around WordPress in March 2014 that indicated it was being used to attack other sites by bypassing the cache and forcing a full reload from the origin server:
If you notice, all queries had a random value (like “?4137049=643182″) that bypassed their cache and force a full page reload every single time. It was killing their server pretty quickly.
But the most interesting part is that all the requests were coming from valid and legitimate WordPress sites. Yes, other WordPress sites were sending that random requests at a very large scale and bringing the site down.
The WordPress exploit was taking advantage of the way "pingbacks" work. Attackers were using sites to add pingbacks to amplify an attack on a third party site (also, ironically, a WordPress site).
It's not just Facebook, or Google - it's inherent in the way caching is designed to work.
Not Just HTTP
This isn't just an issue with HTTP. We can see similar behavior in a DNS exploit that renders DNS caching ineffective as protection against certain attack types. In the DNS case, querying a cache with a random host name results in a query to the authoritative (origin) DNS service. If you send enough random host names at the cache, eventually the DNS service is going to feel the impact and possibly choke.
In general, these types of exploits are based on protocol and well-defined system behavior. A cache is, by design, required to either return a matching object if found or go to the origin server if it is not. In both the HTTP and DNS case, the caching services are acting properly and as one would expect.
The problem is that this proper behavior can be exploited to affect a DDoS attack - against third-parties in the case of Facebook/Google and against the domain owner in the case of DNS.
These are not vulnerabilities, they are protocol exploits. This same "vulnerability" is probably present in most architectures that include caching. The difference is that Facebook's ginormous base of users allows for what is expected behavior to quickly turn into what looks like an attack.
The general consensus right now is the best way to mitigate this potential "attack" is to identify and either rate limit or disallow requests coming from Facebook's crawlers by IP address. In essence, the suggestion is to blacklist Facebook (and perhaps Google) to keep it from potentially overwhelming your site.
The author noted in his post regarding this exploit that:
Facebook crawler shows itself as facebookexternalhit. Right now it seems there is no other choice than to block it in order to avoid this nuisance.
The post was later updated to note that blocking by agent may not be enough, hence the consensus on IP-based blacklisting.
The problem is that attackers could simply find another site with a large user base (there are quite a few of them out there with the users to support a successful attack) and find the right mix of queries to bypass the cache (cause caches are a pretty standard part of a web-scale infrastructure) and voila! Instant attack.
Blocking Facebook isn't going to stop other potential attacks and it might seriously impede revenue generating strategies that rely on Facebook as a channel. Rate limiting based on inbound query volume for specific content will help mitigate the impact (and ensure legitimate requests continue to be served) but this requires some service to intermediate and monitor inbound requests and, upon seeing behavior indicative of a potential attack, the ability to intercede or apply the appropriate rate limiting policy. Such a policy could go further and blacklist IP addresses showing sudden increases in requests or simply blocking requests for the specified URI in question - returning instead some other content.
Another option would be to use a caching solution capable of managing dynamic content. For example, F5 Dynamic Caching includes the ability to designate parameters as either indicative of new content or not. That is, the caching service can be configured to ignore some (or all) parameters and serve content out of cache instead of hammering on the origin server.
Let's say the URI for an image was: /directory/images/dog.gif?ver=1;sz=728X90 where valid query parameters are "ver" (version) and "sz" (size). A policy can be configured to recognize "ver" as indicative of different content while all other query parameters indicate the same content and can be served out of cache. With this kind of policy an attacker could send any combination of the following and the same image would be served from cache, even though "sz" is different and there are random additional query parameters.
/directory/images/dog.gif?ver=1;sz=728X90; id=1234 /directory/images/dog.gif?ver=1;sz=728X900; id=123456 /directory/images/dog.gif?ver=1;sz=728X90; cid=1234
By placing an application fluent cache service in front of your origin servers, when Facebook (or Google) comes knocking, you're able to handle the load.
There have been no reports of an attack stemming from this exploitable condition in Facebook Notes or Google, so blacklisting crawlers from either Facebook or Google seems premature. Given that this condition is based on protocol behavior and system design and not a vulnerability unique to Facebook (or Google), though, it would be a good idea to have a plan in place to address, should such an attack actually occur - from there or some other site.
You should review your own architecture and evaluate its ability to withstand a sudden influx of dynamic requests for content like this, and put into place an operational plan for dealing with it should such an event occur.
For more information on protecting against all types of DDoS attacks, check out a new infographic we’ve put together here.
The Software Defined Data Center (SDDC), which enables organizations to seamlessly run in a hybrid cloud model (public + private cloud), is here to stay. IDC estimates that the software-defined networking market will be valued at $3.7 billion by 2016. Security is a key component and benefit of the SDDC, and offers an opportunity to build security 'from the ground up' and weave it into the environment from day one. In his session at 16th Cloud Expo, Reuven Harrison, CTO and Co-Founder of Tufin,...
Jan. 31, 2015 02:15 PM EST Reads: 2,679
“We are strong believers in the DevOps movement and our staff has been doing DevOps for large enterprise environments for a number of years. The solution that we build is intended to allow DevOps teams to do security at the speed of DevOps," explained Justin Lundy, Founder & CTO of Evident.io, in this SYS-CON.tv interview at DevOps Summit, held Nov 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
Jan. 31, 2015 02:00 PM EST Reads: 3,606
SYS-CON Media announced that Splunk, a provider of the leading software platform for real-time Operational Intelligence, has launched an ad campaign on Big Data Journal. Splunk software and cloud services enable organizations to search, monitor, analyze and visualize machine-generated big data coming from websites, applications, servers, networks, sensors and mobile devices. The ads focus on delivering ROI - how improved uptime delivered $6M in annual ROI, improving customer operations by minin...
Jan. 31, 2015 02:00 PM EST Reads: 5,942
The move in recent years to cloud computing services and architectures has added significant pace to the application development and deployment environment. When enterprise IT can spin up large computing instances in just minutes, developers can also design and deploy in small time frames that were unimaginable a few years ago. The consequent move toward lean, agile, and fast development leads to the need for the development and operations sides to work very closely together. Thus, DevOps become...
Jan. 31, 2015 02:00 PM EST Reads: 4,511
Puppet Labs on Wednesday released the DevOps Salary Report, based on salary data gathered from Puppet Labs' industry-recognized State of DevOps Report. The data confirms that market demand for DevOps skills is growing, and that DevOps engineers are among the highest paid IT practitioners today. That's because IT organizations today are grappling with how to be more agile and responsive to the business, while maintaining the stability of their infrastructure. DevOps practices, such as continuous ...
Jan. 31, 2015 02:00 PM EST Reads: 2,475
CloudBees, Inc., has announced a $23.5 million financing round, led by longtime CloudBees investor Lightspeed Venture Partners. Existing investors Matrix Partners, Verizon Ventures and Blue Cloud Ventures also participated in the round. The latest funding announcement follows earlier rounds of $4 million, $10.5 million and $10.8 million, bringing the total investment in CloudBees to just under $50 million since the company’s inception in 2010. Previous venture investment rounds were led by Ma...
Jan. 31, 2015 02:00 PM EST Reads: 1,473
The cloud is becoming the de-facto way for enterprises to leverage common infrastructure while innovating and one of the biggest obstacles facing public cloud computing is security. In his session at 15th Cloud Expo, Jeff Aliber, a global marketing executive at Verizon, discussed how the best place for web security is in the cloud. Benefits include: Functions as the first layer of defense Easy operation –CNAME change Implement an integrated solution Best architecture for addressing network-l...
Jan. 31, 2015 01:30 PM EST Reads: 3,686
DevOps Summit 2015 New York, co-located with the 16th International Cloud Expo - to be held June 9-11, 2015, at the Javits Center in New York City, NY - announces that it is now accepting Keynote Proposals. The widespread success of cloud computing is driving the DevOps revolution in enterprise IT. Now as never before, development teams must communicate and collaborate in a dynamic, 24/7/365 environment. There is no time to wait for long development cycles that produce software that is obsolete...
Jan. 31, 2015 01:15 PM EST Reads: 4,462
In this scenarios approach Joe Thykattil, Technology Architect & Sales at TimeWarner / Navisite, presented examples that will allow business-savvy professionals to make informed decisions based on a sound business model. This model covered the technology options in detail as well as a financial analysis. The TCO (Total Cost of Ownership) and ROI (Return on Investment) demonstrated how to start, develop and formulate a business case that will allow both small and large scale projects to achieve...
Jan. 31, 2015 01:00 PM EST Reads: 3,624
IBM has announced a new strategic technology services agreement with Anthem, Inc., a health benefits company in the U.S. IBM has been selected to provide operational services for Anthem's mainframe and data center server and storage infrastructure for the next five years. Among the benefits of the relationship, Anthem has the ability to leverage IBM Cloud solutions that will help increase the ease, availability and speed of adding infrastructure to support new business requirements.
Jan. 31, 2015 01:00 PM EST Reads: 2,600
Today, IT is not just a cost center. IT is an enabler and driver of business. With the emergence of the hybrid cloud paradigm, IT now has increasingly more capabilities to create new strategic opportunities for a business. Hybrid cloud allows an organization to utilize multi-tenant public clouds, dedicated private clouds, bare metal hosting, and the associated support and services for the right use cases through an on-demand, XaaS model. This model of IT creates tremendous opportunities for busi...
Jan. 31, 2015 01:00 PM EST Reads: 2,634
Cloud computing started a technology revolution; now DevOps is driving that revolution forward. By enabling new approaches to service delivery, cloud and DevOps together are delivering even greater speed, agility, and efficiency. No wonder leading innovators are adopting DevOps and cloud together! In his session at DevOps Summit, Andi Mann, Vice President of Strategic Solutions at CA Technologies, explored the synergies in these two approaches, with practical tips, techniques, research data, wa...
Jan. 31, 2015 01:00 PM EST Reads: 4,377
Software AG and Wipro Ltd. have announced a joint solution platform for streaming analytics that provides real-time actionable intelligence for the Internet of Things (IoT) market. “The key to successfully addressing the IoT market is the ability to rapidly build and evolve apps that tap into, analyze and make smart decisions on fast, big data”, said John Bates, Global Head of Industry Solutions and CMO, Software AG. To address the huge market potential created by streaming analytics in conj...
Jan. 31, 2015 01:00 PM EST Reads: 1,880
Appcore deploys cloud for service providers based on the Apache Cloud set. In this demo at 15th Cloud Expo, Nate Gordon, Director of Technology at Appcore, shows their new product that's coming out in January - Appcore Atlas, which is focused on deploying private clouds based on CloudStack in 15 minutes or less. Our upcoming June 9-11, 2015, event in New York City will present a total of 10 simultaneous tracks (the largest conference content in the world) by an all-star faculty, over three days...
Jan. 31, 2015 01:00 PM EST Reads: 2,628
The term culture has had a polarizing effect among DevOps supporters. Some propose that culture change is critical for success with DevOps, but are remiss to define culture. Some talk about a DevOps culture but then reference activities that could lead to culture change and there are those that talk about culture change as a set of behaviors that need to be adopted by those in IT. There is no question that businesses successful in adopting a DevOps mindset have seen departmental culture change, ...
Jan. 31, 2015 12:45 PM EST Reads: 3,999
In a world of ever-accelerating business cycles and fast-changing client expectations, the cloud increasingly serves as a growth engine and a path to new business models. Dynamic clouds enable businesses to continuously reinvent themselves, adapting their business processes, their service and software delivery and their operations to achieve speed-to-market and quick response to customer feedback. As the cloud evolves, the industry has multiple competing cloud technologies, offering on-premises ...
Jan. 31, 2015 12:15 PM EST Reads: 3,910
SYS-CON Events announced today that that Innodisk, the service-driven provider of industrial embedded flash and DRAM storage products and technologies, will exhibit at SYS-CON's 16th International Cloud Expo®, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. Innodisk is a service-driven provider of industrial embedded flash and DRAM storage products and technologies. With satisfied customers across the embedded, aerospace and defense, cloud storage markets an...
Jan. 31, 2015 12:00 PM EST Reads: 1,363
Connected devices and the Internet of Things are getting significant momentum in 2014. In his session at Internet of @ThingsExpo, Jim Hunter, Chief Scientist & Technology Evangelist at Greenwave Systems, examined three key elements that together will drive mass adoption of the IoT before the end of 2015. The first element is the recent advent of robust open source protocols (like AllJoyn and WebRTC) that facilitate M2M communication. The second is broad availability of flexible, cost-effective ...
Jan. 31, 2015 12:00 PM EST Reads: 4,665
The Internet of Things will put IT to its ultimate test by creating infinite new opportunities to digitize products and services, generate and analyze new data to improve customer satisfaction, and discover new ways to gain a competitive advantage across nearly every industry. In order to help corporate business units to capitalize on the rapidly evolving IoT opportunities, IT must stand up to a new set of challenges. In his session at @ThingsExpo, Jeff Kaplan, Managing Director of THINKstrateg...
Jan. 31, 2015 11:45 AM EST Reads: 4,724
"Our premise is Docker is not enough. That's not a bad thing - we actually love Docker. At ActiveState all our products are based on open source technology and Docker is an up-and-coming piece of open source technology," explained Bart Copeland, President & CEO of ActiveState Software, in this SYS-CON.tv interview at DevOps Summit at Cloud Expo®, held Nov 4-6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
Jan. 31, 2015 11:45 AM EST Reads: 4,295