CVE-2020-10744: Ansible Vulnerability & Mitigation

by Alex Johnson 51 views

This article dives into the CVE-2020-10744 vulnerability detected in ansible-2.8.19.tar.gz. We will explore the details of this medium severity issue, its potential impact, and the recommended steps for mitigation. This information is crucial for anyone using Ansible in their IT automation workflows, especially within environments like snowdensb and datagov-deploy.

What is CVE-2020-10744?

CVE-2020-10744 refers to a security vulnerability within Ansible, a radically simple IT automation engine. Specifically, it stems from an incomplete fix related to insecure temporary directory handling when using the become_user directive. This vulnerability can lead to a race condition on systems employing Access Control Lists (ACLs) and Filesystem in Userspace (FUSE) filesystems. The initial fix intended to address this issue proved insufficient in preventing the race condition under these circumstances.

This flaw affects Ansible Engine versions 2.7.18, 2.8.12, and 2.9.9, as well as earlier versions. Furthermore, it impacts Ansible Tower versions 3.4.5, 3.5.6, and 3.6.4, along with their preceding releases. The core of the problem lies in how Ansible manages temporary directories when escalating privileges with the become directive. A race condition can occur if these temporary directories are not securely created, potentially allowing unauthorized access or modification.

Vulnerable Library: ansible-2.8.19.tar.gz

The specific vulnerable library identified is ansible-2.8.19.tar.gz. This package is a core component of Ansible, responsible for its automation capabilities. The vulnerability resides within the way this library handles temporary files and user privilege escalation. To understand the scope, let's break down where this library fits within a project:

  • Library Home Page: The official source for this library is located at https://files.pythonhosted.org/packages/5f/c6/106dbd1fb4965baeff90f8b9263c72cdeb18d66135ebf70c64db43245f84/ansible-2.8.19.tar.gz. This link provides access to the library package itself.
  • Path to Dependency File: The vulnerability was found through the dependency file /Pipfile. This file is commonly used in Python projects to manage dependencies, outlining the libraries and versions required for the project to function correctly.
  • Path to Vulnerable Library: The vulnerable library is located within /Pipfile,/Pipfile, indicating its presence within the project's dependency structure.
  • Dependency Hierarchy: The hierarchy clearly shows that ansible-2.8.19.tar.gz is the vulnerable library, sitting at the base of the dependency chain. This means any project relying on this version of Ansible is potentially at risk.

This vulnerability was identified in the master branch, highlighting the importance of addressing it promptly to prevent it from propagating to production environments.

Detailed Look at the Vulnerability

To fully grasp the implications of CVE-2020-10744, it’s essential to delve into the technical details. The vulnerability stems from an incomplete fix for an insecure temporary directory issue within Ansible. When Ansible executes tasks that require elevated privileges using the become directive (e.g., become_user), it creates temporary directories to perform these operations. The initial fix for this issue (CVE-2020-1733) was intended to secure these temporary directories and prevent unauthorized access.

However, the implemented fix proved to be insufficient, particularly in environments that utilize Access Control Lists (ACLs) and FUSE filesystems. In these setups, a race condition can occur. A race condition is a scenario where the outcome of a program depends on the unpredictable order or timing of events. In this context, a malicious actor could potentially exploit the timing gap in the creation and configuration of the temporary directory to gain unauthorized access or modify files.

This means that even with the initial fix, systems using ACLs and FUSE remain vulnerable to potential security breaches. An attacker might be able to manipulate the temporary directory, leading to privilege escalation or other malicious activities. This is a significant concern, especially in shared environments or systems with sensitive data.

The vulnerability was publicly disclosed on May 15, 2020, emphasizing the urgency for users to address the issue. More information about the vulnerability can be found at the Mend vulnerability database (https://www.mend.io/vulnerability-database/CVE-2020-10744). This database provides a comprehensive overview of the vulnerability, including its technical details, affected versions, and recommended solutions.

CVSS 3.0 Score and Impact

The Common Vulnerability Scoring System (CVSS) is a standardized method for assessing the severity of security vulnerabilities. CVE-2020-10744 has a CVSS 3.0 base score of 5.0, which is classified as Medium severity. While not the highest severity, a medium score still indicates a significant risk that requires attention.

The CVSS score is calculated based on a set of metrics that evaluate different aspects of the vulnerability. These metrics fall into two main categories: Exploitability Metrics and Impact Metrics.

Exploitability Metrics:

These metrics assess the ease with which the vulnerability can be exploited.

  • Attack Vector: Local (L): This indicates that the attacker needs local access to the system to exploit the vulnerability. This means the attacker must already have some level of access, either through a compromised account or physical access to the system.
  • Attack Complexity: High (H): This metric suggests that exploiting the vulnerability is not straightforward and requires specific conditions to be met. The race condition scenario makes successful exploitation more complex.
  • Privileges Required: Low (L): An attacker with low-level privileges can exploit this vulnerability. This is concerning because even a user with limited permissions can potentially escalate their privileges.
  • User Interaction: Required (R): User interaction is necessary for the exploitation to occur. This might involve tricking a user into running a specific playbook or command.
  • Scope: Changed (C): This signifies that the vulnerability can affect resources beyond the attacker's control. Successful exploitation could lead to the attacker gaining access to other parts of the system.

Impact Metrics:

These metrics evaluate the potential consequences of a successful exploit.

  • Confidentiality Impact: Low (L): The vulnerability could lead to limited disclosure of sensitive information.
  • Integrity Impact: Low (L): There is a possibility of limited modification of data due to the vulnerability.
  • Availability Impact: Low (L): The vulnerability might cause a partial disruption of system services.

The combination of these metrics results in the CVSS 3.0 score of 5.0. While the impact is considered low across confidentiality, integrity, and availability, the potential for privilege escalation and the changed scope make this a vulnerability that should not be ignored. For a more detailed explanation of CVSS scores, you can refer to the CVSS calculator provided by FIRST (https://www.first.org/cvss/calculator/3.0).

Recommended Fix and Mitigation

The suggested fix for CVE-2020-10744 is to upgrade your Ansible version to a patched release. This is the most effective way to address the vulnerability and prevent potential exploitation. The specific fixed versions are:

  • Ansible 2.8.13
  • Ansible 2.9.10

These versions contain the necessary security patches to address the incomplete fix and mitigate the race condition vulnerability. Upgrading ensures that you are running a secure version of Ansible and reduces your risk exposure.

Upgrade Instructions

The upgrade process will vary depending on how you installed Ansible. However, the general steps are as follows:

  1. Identify your current Ansible version: You can check your current version by running the command ansible --version in your terminal.
  2. Determine your installation method: Did you install Ansible using pip, your system's package manager (e.g., apt, yum), or another method?
  3. Follow the appropriate upgrade instructions:
    • If you used pip: Use the command pip install ansible==<version> (e.g., pip install ansible==2.9.10) to upgrade to a specific version.
    • If you used a package manager: Use your system's package manager to upgrade Ansible. For example, on Debian/Ubuntu systems, you would use sudo apt update && sudo apt install ansible=2.9.10-1~ppa~bionic (replace 2.9.10-1~ppa~bionic with the appropriate version for your system).
  4. Verify the upgrade: After the upgrade, run ansible --version again to confirm that you are running the patched version.

Additional Mitigation Strategies

While upgrading is the primary solution, consider these additional steps for enhanced security:

  • Review Ansible Playbooks: Examine your playbooks for any potentially insecure practices related to temporary file handling or privilege escalation. Ensure that you are using best practices for secure automation.
  • Implement Least Privilege: Configure Ansible to use the principle of least privilege. This means granting only the necessary permissions to users and tasks, minimizing the potential impact of a successful exploit.
  • Regular Security Audits: Conduct regular security audits of your Ansible infrastructure to identify and address potential vulnerabilities proactively.

Automatic Remediation

The information indicates that automatic remediation will be attempted for this issue. This suggests that there are automated systems in place to identify and apply the necessary patches or upgrades. However, it is crucial to verify that the automatic remediation was successful and that your systems are indeed running the patched versions of Ansible. Relying solely on automated remediation without manual verification can leave you vulnerable if the process fails or encounters issues.

Conclusion

CVE-2020-10744 is a medium severity vulnerability affecting ansible-2.8.19.tar.gz and other versions. It stems from an incomplete fix for insecure temporary directory handling, potentially leading to race conditions on systems using ACLs and FUSE filesystems. The recommended solution is to upgrade to Ansible version 2.8.13 or 2.9.10. In addition to upgrading, reviewing playbooks, implementing least privilege, and conducting regular security audits are essential steps for maintaining a secure Ansible environment.

Remember to always stay informed about security vulnerabilities and promptly apply necessary patches to protect your systems and data. For further information on security best practices and vulnerability management, consider exploring resources from trusted sources such as NIST (National Institute of Standards and Technology).