SYS-CON MEDIA Authors: Zakia Bouachraoui, Elizabeth White, Liz McMillan, Yeshim Deniz, William Schmarzo

Blog Feed Post

The Curious Case of the WordPress Docker Container and the Devious XML-RPC Denial of Service Attack

Republished from 04/29 as it was lost due to a Docker Container crash… Irony!

I have an article in the recently released “DZone Guide to Building and Deploying Applications on the Cloud” entitled “Fullstack Engineering in the Age of Hybrid Cloud”. In this article I discuss the need and skills of a Fullstack Engineer with relation to troubleshooting and repairing complex, distributed hybrid cloud applications. My recent experiences with troubleshooting issues with my Docker WordPress container only reinforce the details I wrote about in this piece. Without my comprehensive understanding of both the infrastructure and application layer I don’t believe I could have achieved resolution (if I have, but more on that later).

1969479-dz-cloud2016cover-lgMy Docker WordPress container has always had issues with the “Error Connecting to Database” issue, but initially it would happen once a month and I would just re-start the container. I had read that the issue was fixed by moving to WordPress 4.5, so I upgraded, which came with its own challenges given these containers are supposed to be immutable.

Unfortunately, I designed my container when Docker architecture was in its infancy and so separating out and linking a MySQL container and the WordPress container as well as storing data on a separate volume are all features which emerged, or became more easily used, in later versions. Eventually, I will need redesign around 1.11 features, but for now, I’m just trying to keep up what I currently have. I did try just moving the database files onto permanent storage mapped in to the container as a volume, but all I did was fight with file permissions for a day and MySQL never ended up starting.

Recently, it became more and more difficult to keep the container up, so I upgraded to the latest Ubuntu 14.04 kernel and when that didn’t seem to help the issue I upgraded Docker from 1.4 to 1.11. None of these seemed to correct the issue. However, Docker 1.11 leverages the new architecture and uses cgroups, which resulted in cgroup out of memory thread killer posting messages to my console.

Screen Shot 2016-04-29 at 6.13.20 AM

Now, I could see that mysqld was being terminated at some point due to insufficient memory. To solve the memory issue, I tried optimizing the WordPress LAMP stack for low memory and even migrated from a 1G virtual machine to a 2G instance. It seems no matter how much memory I threw at this problem the longest the WordPress site would be active before the database connection issue appeared was an hour.

Totally baffled at this point, I started chasing down a lead regarding WordPress issues occurring on my cloud service provider. It seemed the issue I was seeing was happening to many others on Digital Ocean, perhaps this was a VPS (DO’s Droplet architecture is VPS-based) issue and not a Docker issue. DO responded on its forum to the various postings stating that running out of memory is common result of the known XML-RPC Denial of Service attack.  XML-RPC is the API interface for WordPress.

Wait! What am I doing? No one’s going to bother attacking my little old blog, it can’t be that. Back to optimizing memory use. Oh crud, this is still not getting me anywhere after two weeks.

Unfortunately, again my immutable container architecture limited my ability to see logs and SSH connections were often terminated due to low memory as well. Once I terminated the container without committing the container the logs were lost. So, I had to modify the current container to use an external volume for all the log files and now wrote them out to permanent storage.

Whoa! What do I find in the apache2 access.log after the next time the issue occurs? Well, when I did a tail of the last 200 entries I found my site was being attacked by a Googlebot, and there were a lot more entries in addition to those. In the end, I was a victim of a denial of service attack.

I believe its important to look at what data I had available and the characteristics identified by the logs and error messages. Nothing screamed DoS attack consuming mass number of threads on the Apache server and driving memory usage to 0 so that the memory manager was sacrificing threads to keep the OS alive (does that make anyone else think of Kirk screaming to Scotty, “all power to life support”?). When the attack stopped, mysqld_safe restored the thread, but it seems the socket or some other interprocess mechanism didn’t allow WordPress to communicate with the MySQL.

Piecing this together after the fact required a mix of skills. It might have been easier if I was doing live monitoring and tracking inbound requests while also constantly checking that WordPress could communicate MySQL, but realistically, this is a dramatic step when all else has failed.

Through this I learned a lot about container architecture, but this issue is probably still lingering. I’m just denying all requests to access XML-RPC from outside IP addresses at this time and the WordPress has been up for over 24 hours. More importantly, it really reinforces what I wrote about in the article and I don’t believe I could have reached this point if I didn’t have a good understanding of the infrastructure, operating system, networking, Docker and LAMP stack

Read the original blog entry...

More Stories By JP Morgenthal

JP Morgenthal is a veteran IT solutions executive and Distinguished Engineer with CSC. He has been delivering IT services to business leaders for the past 30 years and is a recognized thought-leader in applying emerging technology for business growth and innovation. JP's strengths center around transformation and modernization leveraging next generation platforms and technologies. He has held technical executive roles in multiple businesses including: CTO, Chief Architect and Founder/CEO. Areas of expertise for JP include strategy, architecture, application development, infrastructure and operations, cloud computing, DevOps, and integration. JP is a published author with four trade publications with his most recent being “Cloud Computing: Assessing the Risks”. JP holds both a Masters and Bachelors of Science in Computer Science from Hofstra University.

Latest Stories
Lori MacVittie is a subject matter expert on emerging technology responsible for outbound evangelism across F5's entire product suite. MacVittie has extensive development and technical architecture experience in both high-tech and enterprise organizations, in addition to network and systems administration expertise. Prior to joining F5, MacVittie was an award-winning technology editor at Network Computing Magazine where she evaluated and tested application-focused technologies including app secu...
CloudEXPO | DevOpsSUMMIT | DXWorldEXPO Silicon Valley 2019 will cover all of these tools, with the most comprehensive program and with 222 rockstar speakers throughout our industry presenting 22 Keynotes and General Sessions, 250 Breakout Sessions along 10 Tracks, as well as our signature Power Panels. Our Expo Floor will bring together the leading global 200 companies throughout the world of Cloud Computing, DevOps, IoT, Smart Cities, FinTech, Digital Transformation, and all they entail. As ...
Atmosera delivers modern cloud services that maximize the advantages of cloud-based infrastructures. Offering private, hybrid, and public cloud solutions, Atmosera works closely with customers to engineer, deploy, and operate cloud architectures with advanced services that deliver strategic business outcomes. Atmosera's expertise simplifies the process of cloud transformation and our 20+ years of experience managing complex IT environments provides our customers with the confidence and trust tha...
Only Adobe gives everyone - from emerging artists to global brands - everything they need to design and deliver exceptional digital experiences. Adobe Systems Incorporated develops, markets, and supports computer software products and technologies. The Company's products allow users to express and use information across all print and electronic media. The Company's Digital Media segment provides tools and solutions that enable individuals, small and medium businesses and enterprises to cre...
Digital Transformation (DX) is a major focus with the introduction of DXWorldEXPO within the program. Successful transformation requires a laser focus on being data-driven and on using all the tools available that enable transformation if they plan to survive over the long term. A total of 88% of Fortune 500 companies from a generation ago are now out of business. Only 12% still survive. Similar percentages are found throughout enterprises of all sizes. We are offering early bird savings...
Cloud-enabled transformation has evolved from cost saving measure to business innovation strategy -- one that combines the cloud with cognitive capabilities to drive market disruption. Learn how you can achieve the insight and agility you need to gain a competitive advantage. Industry-acclaimed CTO and cloud expert, Shankar Kalyana presents. Only the most exceptional IBMers are appointed with the rare distinction of IBM Fellow, the highest technical honor in the company. Shankar has also receive...
In his keynote at 19th Cloud Expo, Sheng Liang, co-founder and CEO of Rancher Labs, discussed the technological advances and new business opportunities created by the rapid adoption of containers. With the success of Amazon Web Services (AWS) and various open source technologies used to build private clouds, cloud computing has become an essential component of IT strategy. However, users continue to face challenges in implementing clouds, as older technologies evolve and newer ones like Docker c...
CloudEXPO | DevOpsSUMMIT | DXWorldEXPO Silicon Valley 2019 will cover all of these tools, with the most comprehensive program and with 222 rockstar speakers throughout our industry presenting 22 Keynotes and General Sessions, 250 Breakout Sessions along 10 Tracks, as well as our signature Power Panels. Our Expo Floor will bring together the leading global 200 companies throughout the world of Cloud Computing, DevOps, IoT, Smart Cities, FinTech, Digital Transformation, and all they entail.
Daniel Jones is CTO of EngineerBetter, helping enterprises deliver value faster. Previously he was an IT consultant, indie video games developer, head of web development in the finance sector, and an award-winning martial artist. Continuous Delivery makes it possible to exploit findings of cognitive psychology and neuroscience to increase the productivity and happiness of our teams.
Yottabyte is a software-defined data center (SDDC) company headquartered in Bloomfield Township, Oakland County, Michigan. The mission of Yottabyte is to enable any organization to easily and economically realize the benefits of the cloud in their own datacenter. The Yottabyte Cloud Software natively virtualizes compute, storage, and network resources into a resilient, automated software-defined cloud infrastructure solution. Both Enterprise IT customers and Service Providers benefit from Yottab...
Eric Taylor, a former hacker, reveals what he's learned about cybersecurity. Taylor's life as a hacker began when he was just 12 years old and playing video games at home. Russian hackers are notorious for their hacking skills, but one American says he hacked a Russian cyber gang at just 15 years old. The government eventually caught up with Taylor and he pleaded guilty to posting the personal information on the internet, among other charges. Eric Taylor, who went by the nickname Cosmo...
DevOpsSUMMIT at CloudEXPO, to be held June 25-26, 2019 at the Santa Clara Convention Center in Santa Clara, CA – announces that its Call for Papers is open. Born out of proven success in agile development, cloud computing, and process automation, DevOps is a macro trend you cannot afford to miss. From showcase success stories from early adopters and web-scale businesses, DevOps is expanding to organizations of all sizes, including the world's largest enterprises – and delivering real results. Am...
Every organization is facing their own Digital Transformation as they attempt to stay ahead of the competition, or worse, just keep up. Each new opportunity, whether embracing machine learning, IoT, or a cloud migration, seems to bring new development, deployment, and management models. The results are more diverse and federated computing models than any time in our history. Unfortunately, there is no single deployment model that solves all of your business goals. You need to maintain the fl...
The benefits of automated cloud deployments for speed, reliability and security are undeniable. The cornerstone of this approach, immutable deployment, promotes the idea of continuously rolling safe, stable images instead of trying to keep up with managing a fixed pool of virtual or physical machines. In this talk, we'll explore the immutable infrastructure pattern and how to use continuous deployment and continuous integration (CI/CD) process to build and manage server images for any platfo...
Automation is turning manual or repetitive IT tasks into a thing of the past-including in the datacenter. Nutanix not only provides a world-class user interface, but also a comprehensive set of APIs to allow the automation of provisioning, data collection, and other tasks. In this session, you'll explore Nutanix APIs-from provisioning to other Day 0, Day 1 operations. Come learn about how you can easily leverage Nutanix APIs for orchestration and automation of infrastructure, VMs, networking, an...