CVE-2025-62725: How a Simple Docker Command Can Hand Over Your Entire System

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Introduction:

A recently patched high-severity vulnerability in Docker Compose, CVE-2025-62725, has sent shockwaves through the DevOps and security communities. Rated a critical CVSS score of 8.9, this flaw transforms seemingly harmless, read-only Docker Compose commands into a vector for complete system compromise. The vulnerability exploits the OCI include statement feature, allowing attackers to achieve arbitrary file write and subsequently, remote code execution, fundamentally breaking the trust model of container management.

Learning Objectives:

  • Understand the mechanism of the OCI include vulnerability in Docker Compose.
  • Learn the immediate mitigation steps, including patching and security auditing.
  • Develop hardening strategies for Docker environments to prevent similar exploits.

You Should Know:

  1. The Anatomy of the Attack: OCI Include Exploitation
    The core of the vulnerability lies in the misuse of the OCI (Open Container Initiative) `include` statement within a `compose.yaml` file. A maliciously crafted YAML file can force Docker Compose to write a file to an arbitrary location on the host filesystem during the OCI resolution phase. This occurs even when running non-execution commands like `docker compose config` or docker compose ps, which are often considered safe.

Vulnerable `compose.yaml` Snippet:

include:
- resource: malicious-oci-artifact
protocol: oci

Step-by-step guide:

  • Step 1: An attacker crafts a malicious OCI artifact hosted on a public or internal registry. This artifact is designed to exploit the file write primitive during resolution.
  • Step 2: They then create a `compose.yaml` file that references this malicious artifact via the `include` directive.
  • Step 3: When a user or automated process runs any `docker compose` command that parses this file (e.g., ps, config), the OCI resolution is triggered.
  • Step 4: The vulnerability is exploited during resolution, writing a file to a specified path on the host. This could be used to overwrite `~/.ssh/authorized_keys` or a system binary like docker.

2. Immediate Mitigation: Patching and Version Verification

The primary mitigation is to immediately update Docker Compose to a patched version. The vulnerability affects versions prior to the fixed releases.

Command to Check Current Version:

docker compose version

Step-by-step guide:

  • Step 1: Run the version check command. You are vulnerable if your version is below `v2.29.2` or `v2.32.1` (for the v2.29.x and v2.32.x streams, respectively).
  • Step 2: Update Docker Desktop through its built-in updater or use your system’s package manager. For Linux, this might involve: 
    sudo apt-get update && sudo apt-get install docker-compose-plugin
  • Step 3: Verify the update was successful by running the version command again and confirming the version number is patched.

3. Detecting Malicious Compose Files: Security Auditing

Proactively auditing your Docker Compose files for the use of external `include` statements is crucial, especially in CI/CD pipelines or from untrusted sources.

Command to Safely Inspect a Compose File (After Patching):

docker compose -f suspect-compose.yaml config --no-oci-includes

Step-by-step guide:

  • Step 1: Use the `config` command to validate and review the composed application configuration. The `–no-oci-includes` flag is critical as it prevents the resolution of OCI includes, neutralizing the attack vector during inspection.
  • Step 2: Scrutinize the output for any unexpected or external resources. Pay close attention to any `include` sections that point to unknown registries or artifacts.
  • Step 3: Implement this command as a pre-commit hook or a CI pipeline step to automatically scan for and block the use of OCI includes if they are not strictly necessary for your workflow.

4. Post-Exploitation: How RCE is Achieved

The arbitrary file write primitive is powerful on its own, but its true danger is in its easy escalation to Remote Code Execution (RCE). Two primary methods were highlighted.

Overwriting `authorized_keys`:

 An attacker's public key would be written to the host user's authorized_keys file.
echo "ssh-rsa AAAAB3NzaC... attacker@machine" > ~/.ssh/authorized_keys

Step-by-step guide:

  • Step 1: The malicious OCI artifact is crafted to write a file whose content is the attacker’s public SSH key.
  • Step 2: The target path for the write operation is set to the root user’s or a privileged user’s `~/.ssh/authorized_keys` file.
  • Step 3: Once the `docker compose ps` command is run, the file is overwritten.
  • Step 4: The attacker can now SSH into the host machine without a password, gaining immediate access. The vulnerability also leaks the server’s IP during OCI resolution, telling the attacker where to connect.

5. System Hardening: Restricting Docker Compose Privileges

A defense-in-depth approach involves running Docker Compose with reduced privileges and implementing filesystem protections.

Command to Make a Binary Immutable (Linux):

sudo chattr +i /usr/bin/docker

Step-by-step guide:

  • Step 1: Identify critical binaries that are common targets for overwriting, such as docker, dockerd, or containerd.
  • Step 2: Use the `chattr` command to set the immutable (+i) flag on these binaries. This prevents any user, including root, from modifying or deleting the file.
  • Step 3: Be aware that this can interfere with legitimate system updates. The flag must be removed (chattr -i) before updating Docker.
  • Step 4: Consider using read-only mounts for sensitive directories like `/usr/bin` or using Security-Enhanced Linux (SELinux) or AppArmor to enforce strict controls on what the Docker daemon can access.

6. Network Security: Blocking Unauthorized OCI Registry Access

Since the exploit requires fetching a malicious OCI artifact, controlling outbound network traffic from your build and production hosts can serve as a critical barrier.

IPTables Rule to Block Outbound Traffic to Unapproved Registries:

sudo iptables -A OUTPUT -p tcp --dport 443 -d registry.hub.docker.com -j ACCEPT
sudo iptables -A OUTPUT -p tcp --dport 443 -j DROP

Step-by-step guide:

  • Step 1: This is a whitelisting approach. The first rule allows outbound HTTPS traffic only to the official Docker Hub registry (registry.hub.docker.com).
  • Step 2: The second rule blocks all other outbound HTTPS traffic. This would prevent Docker Compose from resolving OCI includes from any other registry, public or private.
  • Step 3: This is a very restrictive policy and will break workflows that rely on other registries (e.g., Google Container Registry, Amazon ECR, Quay.io). Adjust the ACCEPT rules to include your organization’s explicitly approved registries.
  • Step 4: Implement these rules in your host’s firewall configuration to ensure they persist after a reboot.
  1. Incident Response: Hunting for Indicators of Compromise (IOCs)
    If you suspect exploitation, you need to know where to look for evidence.

Commands to Check for SSH Key Modifications and Suspicious Processes:

 Check the last modification time of authorized_keys
ls -la ~/.ssh/authorized_keys
 Check for active SSH sessions from unknown IPs
netstat -tnpa | grep :22
 Audit the Docker Compose command history from the shell history
history | grep "compose"

Step-by-step guide:

  • Step 1: Use `ls -la` to check the timestamp of the `authorized_keys` file. A recent change from around the time a `docker compose` command was run is a major red flag.
  • Step 2: Inspect the contents of the file to ensure it only contains authorized public keys.
  • Step 3: Use `netstat` to look for established SSH connections on port 22. Correlate the IP addresses with your list of known and trusted entities.
  • Step 4: Review the shell history for any `docker compose` commands that were executed, noting the time and the user who ran them. Unexplained commands from service accounts are a critical IOC.

What Undercode Say:

  • The Illusion of “Read-Only” is Shattered. This vulnerability fundamentally changes the risk assessment of Docker Compose. Operations previously deemed low-risk, such as checking service status (ps) or validating configuration (config), must now be treated with the same caution as container execution. Automation and CI/CD pipelines that invoke these commands are particularly vulnerable.
  • Supply Chain Attacks are Now Trivial. The ease with which an external OCI artifact can be incorporated and triggered makes this a perfect vector for software supply chain attacks. A single compromised dependency in a `compose.yaml` file can lead to a full host takeover, emphasizing the need for rigorous software bill of materials (SBOM) and artifact provenance.

The analysis from Undercode suggests that CVE-2025-62725 is a watershed moment for container security. It exposes a critical flaw in the trust boundary between the container orchestration tool and the host OS. The fact that the attack preempts execution and exploits a design feature (OCI includes) rather than a simple code bug indicates a deeper class of vulnerability in modern DevOps tooling. This will likely lead to increased scrutiny on other “resolution-time” or “build-time” processes in similar platforms, pushing the industry towards a zero-trust model even for development and orchestration tools.

Prediction:

The discovery of CVE-2025-62725 will have a lasting impact on how security researchers and attackers view container management platforms. We predict a surge in research focused on the “pre-execution” phases of container workflows, including image manifest resolution, configuration parsing, and plugin systems. This will likely lead to the discovery of similar vulnerabilities in other tools within the CNCF landscape (e.g., Podman, Kubernetes operators). In the short term, automated botnets will likely begin scanning public GitHub repositories and CI/CD systems for unpatched Docker Compose versions and maliciously crafted `compose.yaml` files, leading to widespread exploitation if patching is not aggressively pursued. This event marks a pivot from attacking running containers to subverting the tools that manage them, a potentially more lucrative attack surface.

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IT/Security Reporter URL:

Reported By: Ronmasas Cve – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅

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