“Welcome to the world of containers! Docker has revolutionized the way we deploy and run applications. But have you ever heard of the term “Docker Unverified Container Images”? Well, buckle up, folks! In this blog post, we’ll dive into the ins and outs of Docker unverified container images & why it’s important to take caution when using them.
Let’s start with a quick example. Imagine you’re about to run a container, and you fire up your terminal and type:
docker run -it my-favourite-image
But wait a minute! You see a warning message pop up stating that the image you’re about to run is an “Unverified Container Image.” But what literally does that mean? Keep reading as we address that question & others in this blog.
What are Docker Unverified Container Images
A Docker container image is a lightweight, standalone and executable package of software that includes everything needed to run a piece of software, including the code, a runtime, libraries, environment variables & config files.
Docker Unverified container images are Docker images that haven’t been officially certified or checked by Docker for security, compatibility and reliability. In other words, these images haven’t gone through Docker’s stringent verification process and could potentially cause harm to your system.
Importance of Understanding Docker Unverified Container Images
It’s crucial to understand the difference between verified & unverified images, as using unverified images can lead to various security and compatibility issues. For example; unverified images could contain malware or vulnerabilities that can compromise the security of your system.
Differences between Verified & Unverified Images
The main difference between verified and unverified images is the level of security and compatibility they provide. Verified images have been tested & certified by Docker, ensuring that they are secure and compatible with your system. Unverified images, on the other hand, haven’t gone through this process and could potentially cause harm to your system.
Another difference between verified & unverified images is the trust factor. When using verified images, you can be confident that the image has been officially certified by Docker & that it is safe for use. With unverified images, there is no guarantee that the image is secure or compatible with your system.
Reasons Why an Image may be Unverified
An image may be unverified for several reasons including:
- It was built with a newer version of Docker than what you have installed
- The image was built by an unknown or untrusted source
- The image hasn’t gone through Docker’s verification process
It’s essential to understand these reasons to make an informed decision when choosing an image to use in your containers.
Example & Explanation of the Warning Message
Let’s take a look at a warning message you might encounter when using a docker unverified container image:
docker run -it my-favourite-image
WARNING: An image for this service was built with a newer version of Docker. This image was not verified for compatibility with the installed version of Docker. It may not work correctly.
This message is a warning from Docker that the image you’re about to run was built with a newer version of Docker and has not been tested for compatibility with the version you have installed. This means that the image may not work correctly or could cause problems with your system.
It’s essential to take these warnings seriously & always use images from trusted sources. In the next sections, we’ll discuss the risks of using unverified container images and the best practices for avoiding them.
Risks of Using Docker Unverified Container Images
Security Risks
Using docker unverified container images can pose a significant security risk to your system. These images may contain malware or vulnerabilities that can compromise the security of your system & leave it open to attack.
Here’s an example of how a docker unverified container image can lead to a security risk;
docker run -it unverified-image ... Successfully installed malicious-package-1.0 ...
Your system is now vulnerable to attacks from malicious-package-1.0
In this example, running an unverified container image led to the installation of a malicious package, compromising the security of your system.
Potential Data Loss
Using docker unverified container images can also result in potential data loss. For example; the image may contain bugs/compatibility issues that can cause data loss or corruption.
Here’s an example of potential data loss caused by a docker unverified container image;
docker run -it unverified-image ... Error: Data corruption detected ...
Your data has been corrupted and is no longer accessible.
In this illustration; running a docker unverified container image resulted in data corruption and loss.
It’s crucial to be aware of the risks of using docker unverified container images & to always use images from trusted sources to avoid these risks.
Real–World Scenario
Using Verified Docker Container Images from Trusted Sources
You’re a software developer working on a project that requires multiple containers to run. To ensure the security and reliability of your project, you follow the best practices outlined in this blog post & use verified Docker container images from trusted sources.
Here’s an example of how you can ensure the security and reliability of your containers;
docker inspect official-image ... "Author": "Docker Library <library@docker.com>" ... The source of the Docker container image is trusted and can be used. # Use a verified Docker container image from a trusted source docker run -it official-image ... Successfully pulled and run the verified Docker container image. # Keep your Docker container images up-to-date docker pull official-image:latest ... Successfully pulled the latest version of the verified Docker container image.
By using verified Docker container images from trusted sources, you ensure that your containers are secure & reliable, minimizing the risk of security vulnerabilities/compatibility issues. Additionally, by keeping your images up-to-date, you ensure that your containers are always running the latest version with the latest security patches.
In this scenario; you’ve successfully minimized the risks of using unverified Docker container images and ensured the security & reliability of your project.
Container IP Address
The IP address of a Docker container refers to the unique network identifier assigned to the container by the host machine. It is used to communicate with other containers or the host machine over a network. The IP address can be static, meaning it stays the same for the lifespan of the container or dynamic, meaning it changes each time the container starts.
To find the IP address of a Docker container, you can use the docker inspect command. Here’s an example:
docker inspect -f '{{.NetworkSettings.IPAddress}}' <container_name_or_id>
This command will return the IP address of the container with the given name or ID.
The fact that each container runs in its own separate namespace on an isolated network prevents containers from contacting one another unless they are deliberately linked to or connected to the same network which is a crucial point to remember.
Scan Container
A Docker container scan can be performed using various tools and services. Here’s an example of a container scan using the popular open-source tool, Clair (Github: Clair):
Pull the Docker image to be scanned
docker pull <image_name>:<image_tag>
Save the Docker image as a tar archive
docker save <image_name>:<image_tag> -o <image_name>.tar
Run the Clair scanner on the tar archive
clair-scanner <image_name>.tar ...
In this example; the Docker image is pulled, saved as a tar archive and then scanned using Clair. The output of the scan is a report of the vulnerabilities found in the image, classified by severity.
It’s important to regularly scan your Docker containers to identify and remediate potential security risks. By doing so, you can ensure the security and compliance of your containers and the applications they run.
Log4J Scanner
Log4j is a popular Java-based logging framework used to log messages from applications. A tool called a Log4j scanner examines log data produced by an application to find problems or recurring patterns of behavior.
Here is a sample Java application that uses Log4j;
import org.apache.log4j.Logger;
public class Example {
private static final Logger logger = Logger.getLogger(Example.class);
public static void main(String[] args) {
logger.info("Application started");
// Perform some actions
logger.info("Application completed");
}
}
In this example; the Log4j library is imported and a Logger object is created to log messages. The info method is used to log messages with the INFO level of severity.
To scan the log data generated by this application, you could use a log analysis tool that integrates with Log4j such as the open-source tool, ELK (Elasticsearch, Logstash & Kibana). This tool can help you to identify patterns & anomalies in the log data, such as high error rates or slow performance.
Preparing the Scanner
The preparation of a scanner depends on the type of scanner you are using. Here are a few steps to prepare a Log4j scanner:
- Install the ELK stack: To prepare a Log4j scanner using the ELK stack, you need to install Elasticsearch, Logstash, and Kibana on your machine.
The Elasticsearch DEB package (Download and install)
wget https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-7.10.1-amd64.deb sudo dpkg -i elasticsearch-7.10.1-amd64.deb
The Logstash DEB package
wget https://artifacts.elastic.co/downloads/logstash/logstash-7.10.1.deb sudo dpkg -i logstash-7.10.1.deb
The Kibana DEB package
wget https://artifacts.elastic.co/downloads/kibana/kibana-7.10.1-amd64.deb sudo dpkg -i kibana-7.10.1-amd64.deb
- Configure Logstash to process the log data: Next, you need to configure Logstash to process the log data generated by your Java application.
input {
file {
path => "/path/to/logs/example.log"
start_position => "beginning"
}
}
filter {
grok {
match => { "message" => "%{TIMESTAMP_ISO8601:timestamp} %{LOGLEVEL:loglevel} %{GREEDYDATA:message}" }
}
date {
match => [ "timestamp", "ISO8601" ]
}
}
output {
elasticsearch {
hosts => [ "localhost:9200" ]
index => "example-logs-%{+YYYY.MM.dd}"
}
}
In this example; Logstash is configured to process the log data stored in the file /path/to/logs/example.log. The filter section uses a Grok pattern to extract the timestamp, log level & message from each log entry. The data is then output to an Elasticsearch index.
- Start the ELK stack: Finally, start the ELK stack to begin processing the log data.
Start Elasticsearch
sudo systemctl start elasticsearch
Start the Logstash
sudo systemctl start logstash
Kibana Start
sudo systemctl start kibana
With these steps, you have prepared a Log4j scanner using the ELK stack. You can now analyze the log data generated by your Java application to identify patterns and issues.
Scanner Execution
Here is an example of how to execute a scanner for Log4J using code:
import org.apache.log4j.Logger;
public class ScannerExample {
static Logger logger = Logger.getLogger(ScannerExample.class);
public static void main(String[] args) {
logger.debug("Scanner started");
// Perform the scan here
// ...
logger.debug("Scanner completed");
}
}
In this example; we are using the Log4J library to log the start & completion of the scanner. The actual scanning logic would go in the place of the comment “Perform the scan here“. You can then configure your Log4J settings to output the log statements to a file or another output location.
Best Practices for Using Unverified Container Images
Verify the Source & Authenticity of the Image
Before using any unverified Docker container image, it’s crucial to verify the source and authenticity of the image. You should only use images from trusted sources that you know & trust.
Here’s an example of verifying the source of an unverified Docker container image;
docker inspect unverified-image ... "Author": "Untrusted Source <untrusted@example.com>" ...
The source of the unverified image is untrusted and should not be used.
In this example, inspecting the unverified Docker container image revealed that it was built by an untrusted source. You should avoid using this image.
Use Images from Trusted Sources
To minimize the risks of using Docker unverified container images, it’s essential to use images from trusted sources. Docker provides an official-library of verified images that you can use for your containers.
Here’s an example of using verified docker container images from a trusted source;
docker run -it dockerlibrary/official-image ...
Successfully pulled and run the official Docker container image.
In this example, using a verified Docker container image from the Docker library ensures that the image is secure and compatible with your system.
Keep your Images up-to-date
To ensure that your Docker container images are secure and compatible, it’s important to keep them up-to-date. Regularly updating your images to the latest version helps to avoid security vulnerabilities & compatibility issues.
Here’s an example of updating a Docker container image;
docker pull dockerlibrary/official-image:latest ...
Successfully pulled the latest version of the official Docker container image.
In this example; updating the Docker container image to the latest version ensures that the image is secure and compatible with your system.
A sample of Trusted Repository Code
Using a trusted repository such as Docker Hub, Quay or Google Container Registry ensures that the images you use are from a known & trusted source. By doing this you can prevent yourself from downloading images from suspicious websites that might be vulnerable or contain malware.
Pull image from a trusted repository
docker pull quay.io/myimage:latest
Verify the source of the image
docker inspect quay.io/myimage:latest
Example for Updating an Image
It is important to regularly update your images to ensure that any vulnerabilities or bugs are fixed. This can be done through automated tools such as a CI/CD pipeline, or manually by checking for updates & downloading them when available.
Pull the latest version of the image
docker pull quay.io/myimage:latest
Stop the running container
docker stop mycontainer
Remove the old container
docker rm mycontainer
Start the new container with the latest image
docker run --name mycontainer -d quay.io/myimage:latest
Example of Scanning an Image for Vulnerabilities
Image scanning tools like Clair or Trivy can help you to identify potential vulnerabilities in your images before they are deployed. This helps to mitigate the risk of an attacker exploiting a vulnerability and compromising your system.
Install the Trivy scanner
curl -L https://github.com/aquasecurity/trivy/releases/download/v0.12.0/trivy_0.12.0_Linux-64bit.tar.gz | tar xz
Scan an image for vulnerabilities
./trivy quay.io/myimage:latest
Conclusion
It’s crucial to be aware of the potential dangers of using unverified Docker container images and to always verify the source and authenticity of the images before using them. Additionally, using images from trusted sources & keeping your images up-to-date can help to minimize the risks associated with using unverified images.
In summary, when it comes to using Docker container images it’s essential to always prioritize security & compatibility. By following the best practices outlined in this blog, you can ensure that your containers are secure and reliable.