CVE-2024-23650: Mobyproject BuildKit DOS Vulnerability

CVE-2024-23650 Overview

CVE-2024-23650 is a Denial of Service vulnerability affecting BuildKit, a toolkit for converting source code to build artifacts. A malicious BuildKit client or frontend could craft a request that causes the BuildKit daemon to crash with a panic. This vulnerability stems from improper handling of exceptional conditions (CWE-754), where the daemon fails to gracefully handle malformed or unexpected input from clients.

Critical Impact

A malicious actor with network access to a BuildKit daemon can crash the service, disrupting container build operations and potentially causing cascading failures in CI/CD pipelines that depend on BuildKit for image building.

Affected Products

• Mobyproject BuildKit versions prior to v0.12.5

Discovery Timeline

• 2024-01-31 - CVE-2024-23650 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2024-23650

Vulnerability Analysis

This vulnerability is classified as Improper Check for Unusual or Exceptional Conditions (CWE-754). BuildKit is designed to receive build instructions from clients and frontends, processing these requests to generate container images. However, the daemon's request handling code does not adequately validate or sanitize certain input conditions, allowing a crafted malicious request to trigger an unhandled panic condition.

The attack requires network access but no authentication or user interaction, making it exploitable by any entity that can communicate with the BuildKit daemon. The vulnerability exclusively impacts service availability without affecting data confidentiality or integrity.

Root Cause

The root cause lies in BuildKit's failure to properly validate exceptional conditions in client requests. When a malicious client or frontend submits a specially crafted request containing unexpected or malformed data, the daemon's processing logic encounters an unhandled state that triggers a Go panic, causing the entire daemon process to crash.

This type of vulnerability commonly occurs when developers assume input will always conform to expected formats, neglecting to implement proper bounds checking and exception handling for edge cases that could be intentionally exploited.

Attack Vector

The attack can be executed remotely over the network by any client that can establish a connection to the BuildKit daemon. The attacker must craft a specific request that exploits the improper input validation. Since BuildKit is commonly exposed in containerized CI/CD environments, this vulnerability could be exploited through:

• Malicious build frontends (e.g., Dockerfiles processed from untrusted sources)
• Direct API calls from compromised or malicious BuildKit clients
• Supply chain attacks where malicious build configurations are injected into build pipelines

The vulnerability allows for repeated exploitation, as each malicious request can crash the daemon, requiring manual intervention or automatic restart mechanisms.

Detection Methods for CVE-2024-23650

Indicators of Compromise

• BuildKit daemon process (buildkitd) unexpectedly terminating with panic stack traces
• Log entries containing Go runtime panic messages related to request processing
• Repeated daemon restarts in automated orchestration systems
• Build job failures coinciding with daemon crashes

Detection Strategies

• Monitor BuildKit daemon process stability and track unexpected terminations
• Implement log analysis to detect panic stack traces in BuildKit logs
• Set up alerts for repeated daemon restarts within short time windows
• Track network connections to BuildKit daemon from untrusted sources

Monitoring Recommendations

• Configure container orchestration platforms (Kubernetes, Docker Swarm) to alert on BuildKit pod/container restarts
• Implement centralized logging to capture and analyze BuildKit daemon output
• Use process monitoring tools to track buildkitd process health and resource consumption
• Establish baseline metrics for normal BuildKit operation to detect anomalous behavior

How to Mitigate CVE-2024-23650

Immediate Actions Required

• Upgrade BuildKit to version v0.12.5 or later immediately
• Audit sources of BuildKit frontends and only use trusted, verified frontends
• Restrict network access to BuildKit daemon to trusted clients only
• Review CI/CD pipelines for use of untrusted Dockerfiles or build configurations

Patch Information

The vulnerability has been fixed in BuildKit version v0.12.5. The fix is available via GitHub PR #4601 and can be obtained from the official release page. For detailed information about the vulnerability and the fix, refer to the GitHub Security Advisory GHSA-9p26-698r-w4hx.

Workarounds

• Avoid using BuildKit frontends from untrusted or unverified sources
• Implement network segmentation to limit access to the BuildKit daemon
• Deploy BuildKit behind authentication mechanisms to restrict client access
• Consider running BuildKit in rootless mode to limit potential impact
• Implement automatic restart policies with rate limiting to maintain availability during potential attacks

# Example: Restrict BuildKit daemon to localhost only
buildkitd --addr unix:///run/buildkit/buildkitd.sock

# Example: Use network policies in Kubernetes to restrict access
# Apply a NetworkPolicy that only allows traffic from trusted namespaces
kubectl apply -f - <<EOF
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: buildkit-access-policy
spec:
  podSelector:
    matchLabels:
      app: buildkitd
  policyTypes:
  - Ingress
  ingress:
  - from:
    - namespaceSelector:
        matchLabels:
          trusted: "true"
EOF