Remote code execution via forced unsigned packages in Ansible apt task

Critical Risk infrastructure-security

ansibleaptpackage-managementcode-injectionsignature-verificationremote-code-executionsupply-chain-attack

What it is

Ansible apt tasks configured with force: yes bypass signature validation and downgrade protections, allowing installation of untrusted, tampered, or malicious packages. This creates a critical attack vector where malicious actors can compromise hosts by injecting tampered packages that execute arbitrary code during installation or runtime, leading to full system compromise and persistent attacker control.

Language:

# VULNERABLE: Ansible apt task with forced unsigned packages
- name: Install packages without verification
  hosts: all
  tasks:
    # VULNERABLE: Force bypasses signature verification
    - name: Install potentially unsafe package
      ansible.builtin.apt:
        name: custom-package
        state: present
        force: yes  # VULNERABLE: Bypasses signature checks
        
    # VULNERABLE: Force with multiple packages
    - name: Install multiple packages unsafely
      ansible.builtin.apt:
        pkg:
          - untrusted-package
          - legacy-software
          - custom-tool
        state: present
        force: yes  # VULNERABLE: Allows unsigned packages
        
    # VULNERABLE: Force with package downgrade
    - name: Downgrade package unsafely
      ansible.builtin.apt:
        name: important-service=1.0.0
        state: present
        force: yes  # VULNERABLE: Bypasses downgrade protection
        allow_downgrade: yes
        
    # VULNERABLE: Force with untrusted repository
    - name: Add untrusted repository
      ansible.builtin.apt_repository:
        repo: "deb [trusted=yes] http://untrusted.example.com/repo stable main"
        state: present
        
    - name: Install from untrusted repo
      ansible.builtin.apt:
        name: malicious-package
        state: present
        force: yes  # VULNERABLE: Installs without verification

# SECURE: Ansible apt configuration with signature verification
- name: Install packages securely
  hosts: all
  tasks:
    # SECURE: Add trusted repository GPG key
    - name: Add trusted repository GPG key
      ansible.builtin.apt_key:
        url: https://trusted.example.com/gpg-key.asc
        state: present
        
    - name: Add trusted repository
      ansible.builtin.apt_repository:
        repo: "deb https://trusted.example.com/repo stable main"
        state: present
        
    # SECURE: Install packages without force parameter
    - name: Install verified package
      ansible.builtin.apt:
        name: trusted-package
        state: present
        # SECURE: Omit force - uses default signature verification
        update_cache: yes
        
    # SECURE: Install multiple packages with verification
    - name: Install packages with verification
      ansible.builtin.apt:
        pkg:
          - trusted-package
          - security-tool
          - monitoring-agent
        state: present
        # SECURE: No force parameter - enforces signature checks
        
    # SECURE: Explicitly disable force if needed
    - name: Install with explicit verification
      ansible.builtin.apt:
        name: critical-package
        state: present
        force: no  # SECURE: Explicitly disable force

💡 Why This Fix Works

Why it happens

Ansible apt tasks are configured with force: yes to bypass signature verification and dependency conflicts, allowing installation of unsigned or tampered packages that could contain malicious code.

Root causes

Bypassed Package Signature Validation

Ansible apt tasks are configured with force: yes to bypass signature verification and dependency conflicts, allowing installation of unsigned or tampered packages that could contain malicious code.

Legacy Package Installation Requirements

Organizations use force: yes to install older package versions or packages from untrusted repositories to maintain compatibility with legacy systems, prioritizing functionality over security validation.

Fixes

Remove Force Parameter from APT Tasks

Remove the force parameter or explicitly set force: no in Ansible apt tasks to enforce default signature verification and prevent installation of unsigned or potentially malicious packages.

Configure Trusted Package Repositories

Ensure all package repositories are properly configured with valid GPG keys and signature verification enabled. Use only trusted HTTPS repositories and verify package authenticity before installation.

Implement Package Version Pinning

Pin specific trusted package versions using Ansible apt module version parameters instead of forcing installation, ensuring reproducible builds while maintaining security validation.

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