Security Breaks: TeamTNT’s DockerHub Credentials Leak

We constantly deploy and study our honeypots to get a view of actively exploited vulnerabilities and misconfigurations on platforms and services that pose cloud security risks. One of these honeypots is based on exposed Docker REST API for analysis from cloud services providers’ and users’ perspectives. Upon analyzing the samples, we realized and were able to understand the threat actors’ use of container registry features for Docker malware and tactics, techniques, and procedures (TTPs).

Our honeypots showed threat actor TeamTNT were leaking credentials from at least two of their attacker-controlled DockerHub accounts, namely alpineos (with over 150,000 pulls) and sandeep078 (with 200 pulls). We have notified Docker about these accounts.

The account alpineos was used in exploitation attempts on our honeypots three times, from mid-September to early October 2021, and we tracked the deployments’ IP addresses to their location in Germany. The threat actors were logged in to their accounts on the DockerHub registry and probably forgot to log out. Unless a user is not logged out manually, the header “X-Registry-Auth” stores the credentials.

These DockerHub profiles were actively used to deploy malicious images containing the following:

1. Rootkits
2. Docker escape kits
3. XMRig Monero miners
4. Credential stealers
5. Kinsing malware
6. Kubernetes exploit kits

In July 2021, we published our research on TeamTNT’s malicious activities and found evidence of the group infiltrating via the Docker API. As a result, we found 26 unique DockerHub accounts that are either compromised or malicious. Of the two we identified here, the most interesting account for study was the alpineos account, which hosted malicious container images with over 150,000 pulls. 

Container registries and Docker daemon

Docker is a container services platform that helps developers follow a write-once-run-anywhere (WORA) practice. It’s simple to use and is favored by developers, as a user can write services and deploy applications at great speed. Most importantly, Docker works with any platform.

Container registries are storage and distribution platforms for container images, similar to how codes or programs are hosted on repositories like GitHub. With the right authorization context, one can simply “pull” an image, create a container based on it, and deploy applications. Many container registries such as DockerHub, Amazon Elastic Container Registry (ECR), and Alibaba Container Registry, to name a few, host container images.