Executive Summary

This vulnerability exists in the BentoML Python library versions prior to 1.4.39. The issue is in the way the library processes the docker.base_image value in the bento.yaml configuration file. Specifically, the value is interpolated into a Dockerfile template without any escaping, newline filtering, or validation.

A maliciously crafted bento.yaml file can include a multi-line docker.base_image value that injects arbitrary Dockerfile directives. When BentoML runs the containerize command, it generates a Dockerfile that includes these injected directives and then executes docker build. This causes the injected RUN commands to be executed on the host machine, potentially allowing an attacker to run arbitrary code.

This vulnerability was fixed in BentoML version 1.4.39.

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Impact Analysis

This vulnerability can have severe impacts because it allows an attacker to execute arbitrary commands on the host system where the BentoML containerization process is run.

• Remote code execution on the host machine without requiring privileges.
• Potential full compromise of the host system, including data theft, system manipulation, or further attacks.
• Disruption of services running on the host due to malicious commands.
• Loss of confidentiality, integrity, and availability of the affected system.

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Mitigation Strategies

To mitigate this vulnerability, upgrade BentoML to version 1.4.39 or later, where the issue has been fixed.

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Compliance Impact

The provided information does not specify how this vulnerability impacts compliance with common standards and regulations such as GDPR or HIPAA.

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Detection Guidance

This vulnerability can be detected by inspecting the contents of the bento.yaml files used in your BentoML deployments, specifically checking the docker.base_image field for multi-line values or suspicious newline characters that could indicate an attempt to inject Dockerfile directives.

You can also monitor the Docker build process triggered by bentoml containerize for unexpected RUN commands or other Dockerfile instructions that do not match the expected base image usage.

Suggested commands to help detect this vulnerability include:

• Use grep or similar tools to find multi-line or suspicious docker.base_image entries in bento.yaml files: grep -Pzo 'docker\.base_image:.*\n.+' bento.yaml
• Check for newline characters or unusual whitespace in the docker.base_image field: grep -E '\\n|\r' bento.yaml
• Monitor Docker build logs for unexpected RUN commands during bentoml containerize execution.
• Audit the version of BentoML in use and ensure it is updated to 1.4.39 or later, where this vulnerability is fixed.

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