CVE-2022-23648: Containerd Information Disclosure Flaw

CVE-2022-23648 Overview

CVE-2022-23648 is an information disclosure vulnerability in containerd, a widely-used container runtime available as a daemon for Linux and Windows systems. A bug was discovered in containerd prior to versions 1.6.1, 1.5.10, and 1.4.12 where containers launched through containerd's CRI (Container Runtime Interface) implementation on Linux with a specially-crafted image configuration could gain access to read-only copies of arbitrary files and directories on the host system.

This vulnerability is particularly concerning because it may bypass policy-based enforcement mechanisms on container setup, including Kubernetes Pod Security Policies, potentially exposing sensitive information from the host filesystem. Both Kubernetes and crictl can be configured to use containerd's CRI implementation, making this vulnerability relevant to a wide range of container orchestration deployments.

Critical Impact

Attackers can craft malicious container images that, when executed, allow read access to arbitrary files on the host system, bypassing container isolation and potentially exposing sensitive credentials, configuration files, and other confidential data.

Affected Products

• Linux Foundation containerd versions prior to 1.6.1, 1.5.10, and 1.4.12
• Debian Linux 11.0
• Fedora 34, 35, and 36

Discovery Timeline

• 2022-03-03 - CVE-2022-23648 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2022-23648

Vulnerability Analysis

This vulnerability stems from improper handling of volume mounts in containerd's CRI implementation when processing specially-crafted container image configurations. The flaw allows containers to escape their intended isolation boundaries and access read-only copies of arbitrary files and directories from the host filesystem.

The vulnerability is exploitable over the network without requiring authentication or user interaction, making it accessible to attackers who can introduce malicious container images into an environment. The impact is primarily on confidentiality, as attackers can read sensitive files but cannot modify them or cause availability issues through this specific vulnerability.

In Kubernetes environments, this vulnerability is especially dangerous because it can bypass Pod Security Policies that are specifically designed to prevent such host filesystem access. Organizations relying on these policies as a security boundary may have a false sense of security.

Root Cause

The root cause of CVE-2022-23648 is improper path validation when mounting volumes in container images. The containerd CRI implementation did not properly use fs.RootPath when mounting volumes, allowing specially-crafted image configurations to reference paths outside the intended container filesystem boundaries. This oversight enabled path traversal attacks through maliciously constructed volume mount specifications in container image configurations.

Attack Vector

An attacker exploiting CVE-2022-23648 would craft a malicious container image with specially designed volume mount configurations. When this image is pulled and executed on a vulnerable containerd host, the improper path handling allows the container process to access files and directories on the host system that should be isolated from container workloads.

The attack scenario typically involves:

1. Creating a container image with crafted volume mount specifications
2. Publishing the malicious image to a registry accessible by the target environment
3. Triggering the target system to pull and run the malicious container
4. Accessing sensitive host files through the improperly mounted volumes

# Security patch release notes for containerd v1.6.1
+# commit to be tagged for new release
+commit = "HEAD"
+
+project_name = "containerd"
+github_repo = "containerd/containerd"
+match_deps = "^github.com/(containerd/[a-zA-Z0-9-]+)$"
+
+# previous release
+previous = "v1.6.0"
+
+pre_release = false
+
+preface = """\
+The first patch release for containerd 1.6 includes a fix for
+[CVE-2022-23648](https://github.com/containerd/containerd/security/advisories/GHSA-crp2-qrr5-8pq7)
+and other issues.
+
+### Notable Updates
+
+* **Use fs.RootPath when mounting volumes** ([GHSA-crp2-qrr5-8pq7](https://github.com/containerd/containerd/security/advisories/GHSA-crp2-qrr5-8pq7))
+* **Return init pid when clean dead shim in runc.v1/v2 shims** ([#6572](https://github.com/containerd/containerd/pull/6572))
+
+See the changelog for complete list of changes"""

Source: GitHub Commit

Detection Methods for CVE-2022-23648

Indicators of Compromise

• Container images with unusual or suspicious volume mount configurations referencing absolute host paths
• Unexpected file access patterns from container processes attempting to read sensitive host files such as /etc/shadow, /etc/kubernetes/, or credential files
• Container images from untrusted registries with complex or obfuscated image layer configurations
• Log entries showing containerd processing volume mounts with path traversal patterns

Detection Strategies

• Monitor container image pull operations and inspect image configurations for suspicious volume mount specifications before deployment
• Implement image scanning tools that analyze container image layer contents and configurations for potential exploitation attempts
• Review containerd and kubelet logs for anomalous volume mount operations or path resolution warnings
• Deploy runtime security tools that monitor container process file access patterns and alert on attempts to access sensitive host paths

Monitoring Recommendations

• Enable detailed logging for containerd CRI operations to capture volume mount activities
• Configure alerts for container processes attempting to access common sensitive host paths like /etc/passwd, /etc/shadow, or Kubernetes secret directories
• Implement network monitoring to detect communications from containers that may indicate data exfiltration following successful file access
• Regularly audit container images in registries for configurations that could exploit this vulnerability

How to Mitigate CVE-2022-23648

Immediate Actions Required

• Upgrade containerd to patched versions: 1.6.1, 1.5.10, or 1.4.12 (or later)
• Audit all container images currently in use for suspicious volume mount configurations
• Implement strict image admission policies to only allow containers from trusted registries
• Review and strengthen Pod Security Policies or Pod Security Standards to add defense in depth

Patch Information

The containerd maintainers have released patched versions that properly use fs.RootPath when mounting volumes, preventing the path traversal attack. The fix is included in the following releases:

• containerd v1.6.1
• containerd v1.5.10
• containerd v1.4.13

The specific fix can be reviewed in the GitHub commit. Additionally, distribution-specific patches are available through Debian Security Advisory DSA-5091 and Fedora Package Announcements.

Workarounds

• Restrict container image sources to only trusted, verified registries until patching is complete
• Implement network segmentation to limit the impact of potential data exfiltration from compromised containers
• Use admission controllers like OPA Gatekeeper or Kyverno to validate and reject container images with suspicious volume configurations
• Consider using alternative container runtimes with proper isolation until containerd can be patched

# Check current containerd version
containerd --version

# Update containerd on Debian/Ubuntu
sudo apt-get update
sudo apt-get install containerd

# Update containerd on Fedora
sudo dnf update containerd

# Restart containerd service after update
sudo systemctl restart containerd

# Verify the updated version
containerd --version