CVE-2020-15257 : Vulnerability Insights and Analysis

containerd-shim API Exposed to Host Network Containers

Understanding CVE-2020-15257

This CVE involves a vulnerability in containerd where the containerd-shim API is improperly exposed to host network containers, potentially allowing malicious containers to run processes with elevated privileges.

What is CVE-2020-15257?

containerd is a widely used container runtime available for Linux and Windows.
Versions 1.3.9 and 1.4.3 of containerd had a flaw where the containerd-shim API was exposed to host network containers.

The Impact of CVE-2020-15257

CVSS Base Score: 5.2 (Medium)
Attack Vector: Local
Privileges Required: Low
Scope: Changed
This vulnerability could allow malicious containers to run processes with elevated privileges.

Technical Details of CVE-2020-15257

The technical aspects of this CVE are as follows:

Vulnerability Description

Access controls for the containerd-shim API socket were insufficient, allowing malicious containers to exploit the vulnerability.

Affected Systems and Versions

Affected versions include containerd < 1.3.9 and >= 1.4.0, < 1.4.3.

Exploitation Mechanism

Malicious containers running in the same network namespace as the shim with an effective UID of 0 could cause new processes to run with elevated privileges.

Mitigation and Prevention

To address CVE-2020-15257, consider the following steps:

Immediate Steps to Take

Update containerd to versions 1.3.9 or 1.4.3 as soon as they are released.
Stop and restart containers started with an old version of containerd-shim.
Deny access to all abstract sockets with AppArmor for vulnerable configurations.

Long-Term Security Practices

Run containers with a reduced set of privileges and non-zero UID.
Use isolated namespaces and avoid sharing namespaces with the host.

Patching and Updates

Regularly update containerd to the latest secure versions.