Kubernetes container runtime CRI-O has make-me-root flaw

Cr8escape priv-escalation bug opens the door to cluster takeovers


A vulnerability in the container runtime engine CRI-O can be exploited by a rogue user to gain root-level access on a host.

In a Kubernetes environment powered by CRI-O, the security hole can be used by a miscreant to move through a cluster as an administrator, install malware, and cause other chaos.

CrowdStrike's threat research team discovered the privilege-escalation flaw in CRI-O version 1.19. The bug, tracked as CVE-2022-0811 and more creatively dubbed cr8escape, received a severity score of 8.8 out of 10.

CrowdStrike privately disclosed the vulnerability, and CRI-O's developers today released a fix while recommending immediate patching. Besides Kubernetes, other software and platforms that depend on or use CRI-O – these include OpenShift and Oracle Container Engine for Kubernetes – may also be vulnerable, CrowdStrike warned.

Each Kubernetes node includes a container runtime such as CRI-O. Among other tasks, the container runtime allows containerized apps to safely share each node's underlying Linux kernel and other resources. As part of this, Linux ensures that when one container alters a kernel setting, this change isn't reflected in other containers or on the host as a whole, thus keeping the containers suitably isolated from each other and the underlying platform, CrowdStrike explained.

"Some parameters are namespaced and can therefore be set in a single container without impacting the system at large," the threat researchers wrote. "Kubernetes and the container runtimes it drives allow pods to update these 'safe' kernel settings while blocking access to others."

And herein lies the security flaw: CRI-O introduced a bug that allows attackers to bypass these safeguards and set kernel parameters. "Due to the addition of sysctl support in version 1.19, [the pinns utility] will now blindly set any kernel parameters it's passed without validation," the threat researchers explained.

This means that anyone who can deploy a pod on a cluster using the CRI-O runtime can "abuse the kernel.core_pattern parameter to achieve container escape and arbitrary code execution as root on any node in the cluster," CrowdStrike continued.

Once they've escaped the container, gained root access to the host, and moved anywhere they want in the cluster, miscreants could perform all types of mischief.

"Invocation of CVE-2022-0811 can allow an attacker to perform a variety of actions on objectives, including execution of malware, exfiltration of data and lateral movement across pods," they wrote.

The team also noted: "Kubernetes is not necessary to invoke CVE-2022-8011. An attacker on a machine with CRI-O installed can use it to set kernel parameters all by itself."

CrowdStrike also offered remediation tips at both the Kubernetes and CRI-O level. At the Kubernetes level, the security vendor said its ideal to "use policies to block pods that contain sysctl settings with '+' or '=' in their value."

As a "less ideal" measure, the security vendor recommended using "the PodSecurityPolicy forbiddenSysctls field to block all sysctls (it's necessary to block all sysctls as the malicious setting is smuggled in a value)."

And then obviously at the CRI-O level: upgrade to a patched version of the container runtime software. CrowdStrike also suggested users "set pinns_path in crio.conf to point to a pinns wrapper that strips the '-s' option before invoking the real pinns. This will prevent pods from updating any kernel parameters, including sensitive ones." ®


Other stories you might like

  • Despite 'key' partnership with AWS, Meta taps up Microsoft Azure for AI work
    Someone got Zuck'd

    Meta’s AI business unit set up shop in Microsoft Azure this week and announced a strategic partnership it says will advance PyTorch development on the public cloud.

    The deal [PDF] will see Mark Zuckerberg’s umbrella company deploy machine-learning workloads on thousands of Nvidia GPUs running in Azure. While a win for Microsoft, the partnership calls in to question just how strong Meta’s commitment to Amazon Web Services (AWS) really is.

    Back in those long-gone days of December, Meta named AWS as its “key long-term strategic cloud provider." As part of that, Meta promised that if it bought any companies that used AWS, it would continue to support their use of Amazon's cloud, rather than force them off into its own private datacenters. The pact also included a vow to expand Meta’s consumption of Amazon’s cloud-based compute, storage, database, and security services.

    Continue reading
  • Atos pushes out HPC cloud services based on Nimbix tech
    Moore's Law got you down? Throw everything at the problem! Quantum, AI, cloud...

    IT services biz Atos has introduced a suite of cloud-based high-performance computing (HPC) services, based around technology gained from its purchase of cloud provider Nimbix last year.

    The Nimbix Supercomputing Suite is described by Atos as a set of flexible and secure HPC solutions available as a service. It includes access to HPC, AI, and quantum computing resources, according to the services company.

    In addition to the existing Nimbix HPC products, the updated portfolio includes a new federated supercomputing-as-a-service platform and a dedicated bare-metal service based on Atos BullSequana supercomputer hardware.

    Continue reading
  • In record year for vulnerabilities, Microsoft actually had fewer
    Occasional gaping hole and overprivileged users still blight the Beast of Redmond

    Despite a record number of publicly disclosed security flaws in 2021, Microsoft managed to improve its stats, according to research from BeyondTrust.

    Figures from the National Vulnerability Database (NVD) of the US National Institute of Standards and Technology (NIST) show last year broke all records for security vulnerabilities. By December, according to pentester Redscan, 18,439 were recorded. That's an average of more than 50 flaws a day.

    However just 1,212 vulnerabilities were reported in Microsoft products last year, said BeyondTrust, a 5 percent drop on the previous year. In addition, critical vulnerabilities in the software (those with a CVSS score of 9 or more) plunged 47 percent, with the drop in Windows Server specifically down 50 percent. There was bad news for Internet Explorer and Edge vulnerabilities, though: they were up 280 percent on the prior year, with 349 flaws spotted in 2021.

    Continue reading
  • ServiceNow takes aim at procurement pain points
    Purchasing teams are a bit like help desks – always being asked to answer dumb or inappropriate questions

    ServiceNow's efforts to expand into more industries will soon include a Procurement Service Management product.

    This is not a dedicated application – ServiceNow has occasionally flirted with templates for its platform that come very close to being apps. Instead it stays close to the company's core of providing workflows that put the right jobs in the right hands, and make sure they get done. In this case, it will do so by tickling ERP and dedicated procurement applications, using tech ServiceNow acquired along with a company called Gekkobrain in 2021.

    The company believes it can play to its strengths with procurements via a single, centralized buying team.

    Continue reading
  • HPE, Cerebras build AI supercomputer for scientific research
    Wafer madness hits the LRZ in HPE Superdome supercomputer wrapper

    HPE and Cerebras Systems have built a new AI supercomputer in Munich, Germany, pairing a HPE Superdome Flex with the AI accelerator technology from Cerebras for use by the scientific and engineering community.

    The new system, created for the Leibniz Supercomputing Center (LRZ) in Munich, is being deployed to meet the current and expected future compute needs of researchers, including larger deep learning neural network models and the emergence of multi-modal problems that involve multiple data types such as images and speech, according to Laura Schulz, LRZ's head of Strategic Developments and Partnerships.

    "We're seeing an increase in large data volumes coming at us that need more and more processing, and models that are taking months to train, we want to be able to speed that up," Schulz said.

    Continue reading
  • We have bigger targets than beating Oracle, say open source DB pioneers
    Advocates for MySQL and PostgreSQL see broader future for movement they helped create

    MySQL pioneer Peter Zaitsev, an early employee of MySQL AB under the original open source database author Michael "Monty" Widenius, once found it easy to identify the enemy.

    "In the early days of MySQL AB, we were there to get Oracle's ass. Our CEO Mårten Mickos was always telling us how we were going to get out there and replace all those Oracle database installations," Zaitsev told The Register.

    Speaking at Percona Live, the open source database event hosted by the services company Zaitsev founded in 2006 and runs as chief exec, he said that situation had changed since Oracle ended up owning MySQL in 2010. This was as a consequence of its acquisition that year of Sun Microsystems, which had bought MySQL AB just two years earlier.

    Continue reading
  • Beijing needs the ability to 'destroy' Starlink, say Chinese researchers
    Paper authors warn Elon Musk's 2,400 machines could be used offensively

    An egghead at the Beijing Institute of Tracking and Telecommunications, writing in a peer-reviewed domestic journal, has advocated for Chinese military capability to take out Starlink satellites on the grounds of national security.

    According to the South China Morning Post, lead author Ren Yuanzhen and colleagues advocated in Modern Defence Technology not only for China to develop anti-satellite capabilities, but also to have a surveillance system that could monitor and track all satellites in Starlink's constellation.

    "A combination of soft and hard kill methods should be adopted to make some Starlink satellites lose their functions and destroy the constellation's operating system," the Chinese boffins reportedly said, estimating that data transmission speeds of stealth fighter jets and US military drones could increase by a factor of 100 through a Musk machine connection.

    Continue reading
  • How to explain what an API is – and why they matter
    Some of us have used them for decades, some are seeing them for the first time on marketing slides

    Systems Approach Explaining what an API is can be surprisingly difficult.

    It's striking to remember that they have been around for about as long as we've had programming languages, and that while the "API economy" might be a relatively recent term, APIs have been enabling innovation for decades. But how to best describe them to someone for whom application programming interfaces mean little or nothing?

    I like this short video from Martin Casado, embedded below, which starts with the analogy of building cars. In the very early days, car manufacturers were vertically integrated businesses, essentially starting from iron ore and coal to make steel all the way through to producing the parts and then the assembled vehicle. As the business matured and grew in size, car manufacturers were able to buy components built by others, and entire companies could be created around supplying just a single component, such as a spring.

    Continue reading

Biting the hand that feeds IT © 1998–2022