Protecting against new Kubernetes threats in 2024 and beyond

A wave of latest assaults focused Kubernetes in 2023: Dero and Monero crypto miners, Scarleteel and RBAC-Buster. Discovering an preliminary foothold with an online app vulnerability, then shifting laterally is the hallmark of a Kubernetes assault. Understanding the truth of those assaults can assist shield your group from present and future assaults focusing on Kubernetes.

Right here’s a breakdown of how the assaults unfold and what you are able to do to guard towards them — or no less than reduce the injury as soon as attacked.

Scarleteel plan of assault

A Jupyter pocket book internet utility hosted in Kubernetes was the entry level for Scarleteel, with the aim of accessing encrypted, delicate information housed in cloud storage and crypto mining. To search out open entry to the AWS cloud surroundings, the attackers additionally used an open-source Kubernetes penetration testing instrument known as Peirates, together with an identical instrument known as Pacu.

Scarleteel demonstrated how fluidly an attacker can transfer by a cloud surroundings. The attacker jumped from an online utility hosted in Kubernetes straight to the cloud to Kubernetes after which again once more. Defenders don’t have a equally linked view of their surroundings, as a substitute taking a look at cloud safety, internet app safety and Kubernetes safety individually, then struggling to place collectively the complete movement and goals of the attacker. 

What you are able to do to guard from Scarleteel

Should you’re not utilizing Jupyter notebooks, you may not be prone to this attack. However there are various different internet app vulnerabilities. You may be certain that you shield towards the very particular cloud misconfiguration the attackers took benefit of. Should you run EKS, look into locations the place you’ve gotten IMDSv1 versus IMDSv2 put in and get a blue crew to run Peirates and Paco towards your surroundings earlier than an attacker does.

Runtime capabilities would probably detect the Pandora malware, however wouldn’t join this to the broader assault and exercise taking place throughout the cloud and Kubernetes environments, so it could possibly’t cease the whole lot of the assault.

Dero and Monero Cryptocurrency Miners

Within the Dero assault, the unhealthy actor first scanned for Kubernetes APIs the place authentication is ready to permit anybody nameless entry. For this to work, the cluster additionally wanted RBAC configuration that allowed for the creation of pods in that cluster. With these circumstances met, the attacker deployed a Daemonset, creating its personal pods from malicious photographs throughout the cluster. 

The primary a part of the Monero assault is similar as Dero. Then, with entry to the Kubernetes API, attackers deleted the Dero pods and deployed their very own privileged pod through Daemonset. The privileged pod then tried to mount the host listing to flee the container and downloaded a rootkit that might disguise the miner. Afterward, the attacker put in a customized mining service on the host.

Not like Dero, the Monero assault entails privilege escalation and container escape methods. Permitting privileged containers is among the most crucial Kubernetes safety points to keep away from. Kubernetes disallows privileged pods in its baseline coverage for Pod Security Standards, making it much less doubtless this may occur by default.

Nevertheless, should you’re operating EKS and Kubernetes v1.13 and above, the default pod safety coverage is privileged. In EKS, you should delete this coverage to allow your buyer insurance policies — an added step that probably will increase the probabilities you’ll permit creation of privileged pods. 

In Monero, there’s quite a lot of runtime exercise that occurs after hackers benefit from the preliminary Kubernetes misconfiguration. Locking this down would forestall malicious runtime habits from spreading to different pods and clusters. Stopping disallowed host mounted paths and privileged pod misconfigurations is an important preventive measure. Should you’re doing KSPM on polling intervals, you’re lacking any attacker exercise that occurs in between.

Methods to shield from the Dero / Monero assaults

If uncovered, your major concern is tamping down the blast radius — because the assault happens in real-time in Kubernetes, not in runtime. In case your runtime functionality features a rule round Monero crypto mining, you may cease the final step however not the preliminary phases of the compromise.

Though you most likely wouldn’t set your API to permit nameless entry, there are different methods this identical entry level could possibly be exploited. A malicious insider might plant backdoors or cryptocurrency miners much like those in these assaults. A developer might unknowingly examine in a service account token or kubeconfig file to a public git repository that might go away a cluster susceptible.

Crucial protecting measure is stopping the creation of malicious workloads from Daemonsets. There’s additionally a case for observability tooling, as many crypto jacking operations are found by sudden visitors spikes.

Since this assault used a picture to create the malicious pods, organising an admission management coverage that forestalls the creation of workloads coming from untrusted picture sources would work. Nevertheless, you’d both need to implement the coverage broadly or make use of a real-time KSPM detection answer to grasp precisely the place you’re having points, then use the admission controller surgically as you repair the configurations in code.

RBAC-Buster plan of assault

The attacker makes an attempt to achieve a foothold in a Kubernetes surroundings by scanning for a misconfigured API server that might permit unauthenticated requests from customers with privileges. Attackers used privileged entry to checklist secrets and techniques and uncover the kube-system namespace.

They created a brand new ClusterRole with admin privileges and a brand new Service Account within the namespace, binding the 2 collectively to provide the ClusterRole’s admin privileges to the Service Account. The attacker regarded for AWS keys to achieve entry to the cloud service supplier. They then used a Daemonset to deploy malicious pods for crypto mining throughout the cluster, utilizing a container picture. 

The preliminary step on this assault assumes that not solely is your Kubernetes API server open, however it’s additionally accepting requests that privileged customers have. The remainder of the assault operates with this privileged entry. 

What you are able to do to guard from RBAC-Buster

To unfold laterally, the attackers used the identical Daemonset approach as within the Dero marketing campaign — a reminder to stop creation of malicious workloads from Daemonsets. Verify your API server configurations and audit your RBAC permissions to guard towards this assault.

Stopping future assaults

The crew that found RBAC-Buster mentioned 60% of uncovered clusters discovered had an active campaign running. This doesn’t imply 60% of all clusters are uncovered. However attackers are looking for errors, misconfigurations and a means into your Kubernetes surroundings.

Most clusters have been solely accessible for just a few hours, highlighting the ephemeral nature of Kubernetes clusters and the way what as we speak factors to an exploitation and publicity may tomorrow be closed off to attackers. This implies a nightmare in remediation should you’re working with polling intervals that may’t present these modifications over time.

Relying solely on admission management or reverse-engineering detection on runtime occasions when the following assault comes both received’t detect it in any respect or will detect it too late. You want a real-time, mixed view of Kubernetes threat. Protection-in-depth is finest follow. However, if defense-in-depth supplies no view of how all of the completely different parts work collectively, you’re nonetheless one step behind the attacker. 

Jimmy Mesta is CTO and co-founder of KSOC.