CVE-2021-37841 in Docker
Summary
by MITRE • 08/12/2021
Docker Desktop before 3.6.0 suffers from incorrect access control. If a low-privileged account is able to access the server running the Windows containers, it can lead to a full container compromise in both process isolation and Hyper-V isolation modes. This security issue leads an attacker with low privilege to read, write and possibly even execute code inside the containers.
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Analysis
by VulDB Data Team • 08/18/2021
The vulnerability identified as CVE-2021-37841 represents a critical access control flaw in Docker Desktop versions prior to 3.6.0 that fundamentally undermines container security boundaries on Windows systems. This issue specifically affects Windows containers operating under both process isolation and Hyper-V isolation modes, creating a pathway for privilege escalation that can result in complete container compromise. The flaw stems from improper implementation of access controls that allow low-privileged users to gain unauthorized access to containerized environments, effectively bypassing the security mechanisms designed to isolate container processes from the host system and other containers.
The technical nature of this vulnerability lies in the inadequate enforcement of access control lists and permission checks within Docker Desktop's Windows container runtime components. When a low-privileged account gains access to the Docker server process running on Windows, the vulnerability enables unauthorized operations including reading container filesystems, writing to container directories, and executing arbitrary code within container contexts. This represents a fundamental breakdown in the principle of least privilege that should normally prevent unauthenticated or unauthorized access to container resources. The vulnerability is particularly concerning because it affects both isolation modes, meaning that even when containers are supposedly running in isolated Hyper-V environments, the access control failure allows for cross-container or host-level attacks that can bypass these protective measures.
From an operational impact perspective, this vulnerability creates significant risk for organizations deploying containerized applications on Windows platforms. Attackers with minimal privileges can exploit this flaw to gain complete control over containerized workloads, potentially leading to data breaches, service disruption, and lateral movement within network environments. The implications extend beyond individual containers to encompass the broader container orchestration ecosystem, as compromised containers can serve as launch points for attacking other systems within the same network segment. Organizations using Docker Desktop for development and testing environments face particular risk since these environments often contain sensitive data and may not implement additional security controls that would normally be present in production deployments.
The vulnerability aligns with CWE-284 which addresses improper access control, and maps to several ATT&CK techniques including privilege escalation through access control bypass and lateral movement through container compromise. Organizations should immediately update to Docker Desktop version 3.6.0 or later to address this issue, as the patch implements proper access control enforcement mechanisms that prevent low-privileged users from accessing container resources. Additional mitigations include restricting physical and network access to systems running Docker Desktop, implementing network segmentation, and monitoring for unauthorized access attempts to containerized environments. Security teams should also conduct thorough assessments of their containerized applications to identify any potential exploitation of this vulnerability and implement comprehensive logging and monitoring solutions to detect unauthorized container access attempts.