Xeol

🔎 A scanner for end-of-life (EOL) packages in container images, filesystems, and SBOMs 🔍

🌐 Website | 📑 Docs | ✍🏻 Blog

Installation

Homebrew

brew tap xeol-io/xeol
brew install xeol

GitHub Actions

If you're using GitHub Actions, you can simply use the Xeol GitHub action to run EOL scans on your code or container images during your CI workflows.

Verifying SLSA provenance for downloaded releases

We generate SLSA provenance for all Xeol releases starting with v0.9.5. You can verify the provenance for the release binaries like so:

Install the slsa-framework/slsa-verifier#installation tool
Download the signature file multiple.intoto.jsonl from a Xeol release
Download the Xeol release binary you want to verify
Run slsa-verifier verify-artifact --provenance-path multiple.intoto.jsonl <release-binary> --source-uri=github.com/xeol-io/xeol

You should see something like this is the release binary is verified:

➜  ~ slsa-verifier verify-artifact --provenance-path multiple.intoto.jsonl xeol_0.9.5_darwin_amd64.tar.gz --source-uri=github.com/xeol-io/xeol
Verified signature against tlog entry index 44906341 at URL: https://rekor.sigstore.dev/api/v1/log/entries/24296fb24b8ad77a658e74e86e03e7aedcca39eebddebf59310b4d9c463b037951109186d73a5681
Verified build using builder "https://github.com/slsa-framework/slsa-github-generator/.github/workflows/generator_generic_slsa3.yml@refs/tags/v1.9.0" at commit fdc6f5efca3f7277aacf25ef42f502355398f512
Verifying artifact xeol_0.9.5_darwin_amd64.tar.gz: PASSED

PASSED: Verified SLSA provenance

Getting started

Install the binary, and make sure that xeol is available in your path. To scan for EOL packages in an image:

xeol <image>

The above command scans for EOL packages that are visible in the container (i.e., the squashed representation of the image). To include software from all image layers in the scan, regardless of its presence in the final image, provide --scope all-layers:

xeol <image> --scope all-layers

To run xeol from a Docker container so it can scan a running container, use the following command:

docker run --rm \
--volume /var/run/docker.sock:/var/run/docker.sock \
--name xeol noqcks/xeol:latest \
$(ImageName):$(ImageTag)

Supported sources

xeol can scan a variety of sources beyond those found in Docker.

# scan a container image archive (from the result of `docker image save ...`, `podman save ...`, or `skopeo copy` commands)
xeol path/to/image.tar

# scan a Singularity Image Format (SIF) container
xeol path/to/image.sif

# scan a directory
xeol dir:path/to/dir

Sources can be explicitly provided with a scheme:

podman:yourrepo/yourimage:tag          use images from the Podman daemon
docker:yourrepo/yourimage:tag          use images from the Docker daemon
docker-archive:path/to/yourimage.tar   use a tarball from disk for archives created from "docker save"
oci-archive:path/to/yourimage.tar      use a tarball from disk for OCI archives (from Skopeo or otherwise)
oci-dir:path/to/yourimage              read directly from a path on disk for OCI layout directories (from Skopeo or otherwise)
singularity:path/to/yourimage.sif      read directly from a Singularity Image Format (SIF) container on disk
dir:path/to/yourproject                read directly from a path on disk (any directory)
sbom:path/to/syft.json                 read Syft JSON from path on disk
registry:yourrepo/yourimage:tag        pull image directly from a registry (no container runtime required)
att:attestation.json --key cosign.pub  explicitly use the input as an attestation

Use SBOMs for even faster EOL scanning in xeol:

# Then scan for new EOL packages as frequently as needed
xeol sbom:./sbom.json

# (You can also pipe the SBOM into xeol)
cat ./sbom.json | xeol

xeol supports input of Syft, SPDX, and CycloneDX SBOM formats. If Syft has generated any of these file types, they should have the appropriate information to work properly with xeol.

Lookahead

By default, xeol will match any package that has an EOL date that is less than the current date + 30d. In order to set a custom lookahead matching time, you can use --lookahead <duration>. where <duration> is like 1w, 30d or 1y.

Gating on EOL packages found

You can have xeol exit with an error if it finds any EOL packages. This is useful for CI/CD pipelines. To do this, use the --fail-on-eol-found CLI flag.

xeol <image> --fail-on-eol-found

What is EOL software?

End of Life (EOL) means the vendor has decided the software in question has reached the end of its “useful lifespan.” After this particular date, the manufacturer no longer markets, sells, provides technical support, sustains, enhances, or fixes the product. Note that End of Life (EOL) and End of Support (EOS) are being treated as the same by xeol, even though various vendors may use these terms differently. EOL Software is a security risk because it is no longer being maintained and receiving security updates.

The data that xeol uses to determine if a package is EOL is sourced from endoflife.date. While endoflife.date includes extended support dates, xeol does not currently support this and we only match on the standard EOL support dates from vendors.

xeol's database

When xeol performs a scan for EOL packages, it does so using a database that's stored on your local filesystem, which is constructed by pulling data from endoflife.date.

By default, xeol automatically manages this database for you. xeol checks for new updates to the database to make sure that every scan uses up-to-date EOL information. This behavior is configurable. For more information, see the Managing xeeol's database section.

How database updates work

xeol's eol database is a SQLite file, named xeol.db. Updates to the database are atomic: the entire database is replaced and then treated as "readonly" by xeol.

xeol's first step in a database update is discovering databases that are available for retrieval. xeol does this by requesting a "listing file" from a public endpoint:

https://data.xeol.io/xeol/databases/listing.json

The listing file contains entries for every database that's available for download.

Here's an example of an entry in the listing file:

{
  "built": "2021-10-21T08:13:41Z",
  "version": 3,
  "url": "https://data.xeol.io/xeol/databases/eol-db_v3_2021-10-21T08:13:41Z.tar.gz",
  "checksum": "sha256:8c99fb4e516f10b304f026267c2a73a474e2df878a59bf688cfb0f094bfe7a91"
}

With this information, xeol can select the correct database (the most recently built database with the current schema version), download the database, and verify the database's integrity using the listed checksum value.

Managing xeol's database

Note: During normal usage, there is no need for users to manage xeol's database! xeol manages its database behind the scenes. However, for users that need more control, xeol provides options to manage the database more explicitly.

Local database cache directory

By default, the database is cached on the local filesystem in the directory $XDG_CACHE_HOME/xeol/db/<SCHEMA-VERSION>/. For example, on macOS, the database would be stored in ~/Library/Caches/xeol/db/3/. (For more information on XDG paths, refer to the XDG Base Directory Specification.)

You can set the cache directory path using the environment variable XEOL_DB_CACHE_DIR.

Data staleness

xeol needs up-to-date information to provide accurate EOL matches. By default, it will fail execution if the local database was not built in the last 5 days. The data staleness check is configurable via the environment variable XEOL_DB_MAX_ALLOWED_BUILT_AGE and XEOL_DB_VALIDATE_AGE or the field max-allowed-built-age and validate-age, under db. It uses golang's time duration syntax. Set XEOL_DB_VALIDATE_AGE or validate-age to false to disable staleness check.

Offline and air-gapped environments

By default, xeol checks for a new database on every run, by making a network call over the Internet. You can tell xeol not to perform this check by setting the environment variable XEOL_DB_AUTO_UPDATE to false.

As long as you place xeol's xeol.db and metadata.json files in the cache directory for the expected schema version, xeol has no need to access the network. Additionally, you can get a listing of the database archives available for download from the xeol db list command in an online environment, download the database archive, transfer it to your offline environment, and use xeol db import <db-archive-path> to use the given database in an offline capacity.

If you would like to distribute your own xeol databases internally without needing to use db import manually you can leverage xeol's DB update mechanism. To do this you can craft your own listing.json file similar to the one found publically (see xeol db list -o raw for an example of our public listing.json file) and change the download URL to point to an internal endpoint (e.g. a private S3 bucket, an internal file server, etc). Any internal installation of xeol can receive database updates automatically by configuring the db.update-url (same as the XEOL_DB_UPDATE_URL environment variable) to point to the hosted listing.json file you've crafted.

CLI commands for database management

xeol provides database-specific CLI commands for users that want to control the database from the command line. Here are some of the useful commands provided:

xeol db status — report the current status of xeol's database (such as its location, build date, and checksum)

xeol db check — see if updates are available for the database

xeol db update — ensure the latest database has been downloaded to the cache directory (xeol performs this operation at the beginning of every scan by default)

xeol db list — download the listing file configured at db.update-url and show databases that are available for download

xeol db import — provide xeol with a database archive to explicitly use (useful for offline DB updates)

Find complete information on xeol's database commands by running xeol db --help.

Shell completion

xeol supplies shell completion through its CLI implementation (cobra). Generate the completion code for your shell by running one of the following commands:

xeol completion <bash|zsh|fish>
go run ./cmd/xeol completion <bash|zsh|fish>

This will output a shell script to STDOUT, which can then be used as a completion script for xeol. Running one of the above commands with the -h or --help flags will provide instructions on how to do that for your chosen shell.

Private Registry Authentication

Local Docker Credentials

When a container runtime is not present, xeol can still utilize credentials configured in common credential sources (such as ~/.docker/config.json). It will pull images from private registries using these credentials. The config file is where your credentials are stored when authenticating with private registries via some command like docker login. For more information see the go-containerregistry documentation.

An example config.json looks something like this:

// config.json
{
    "auths": {
        "registry.example.com": {
            "username": "AzureDiamond",
            "password": "hunter2"
        }
    }
}

You can run the following command as an example. It details the mount/environment configuration a container needs to access a private registry:

docker run -v ./config.json:/config/config.json -e "DOCKER_CONFIG=/config" noqcks/xeol:latest <private_image>

Docker Credentials in Kubernetes

The below section shows a simple workflow on how to mount this config file as a secret into a container on kubernetes.

Create a secret. The value of config.json is important. It refers to the specification detailed here. Below this section is the secret.yaml file that the pod configuration will consume as a volume. The key config.json is important. It will end up being the name of the file when mounted into the pod.
```
    apiVersion: v1
    kind: Secret
    metadata:
      name: registry-config
      namespace: xeol
    data:
      config.json: <base64 encoded config.json>
```
```
`kubectl apply -f secret.yaml`
```

Create your pod running xeol. The env DOCKER_CONFIG is important because it advertises where to look for the credential file. In the below example, setting DOCKER_CONFIG=/config informs xeol that credentials can be found at /config/config.json. This is why we used config.json as the key for our secret. When mounted into containers the secrets' key is used as the filename. The volumeMounts section mounts our secret to /config. The volumes section names our volume and leverages the secret we created in step one.


    apiVersion: v1
    kind: Pod
    spec:
      containers:
        - image: noqcks/xeol:latest
          name: xeol-private-registry-demo
          env:
            - name: DOCKER_CONFIG
              value: /config
          volumeMounts:
          - mountPath: /config
            name: registry-config
            readOnly: true
          args:
            - <private_image>
      volumes:
      - name: registry-config
        secret:
          secretName: registry-config

`kubectl apply -f pod.yaml`

The user can now run kubectl logs xeol-private-registry-demo. The logs should show the xeol analysis for the <private_image> provided in the pod configuration.

Using the above information, users should be able to configure private registry access without having to do so in the xeol or syft configuration files. They will also not be dependent on a docker daemon, (or some other runtime software) for registry configuration and access.

Configuration

Configuration search paths:

.xeol.yaml
.xeol/config.yaml
~/.xeol.yaml
<XDG_CONFIG_HOME>/xeol/config.yaml

Pronunciation

Xeol is pronounced "zee-oh-el", like EOL but with a Z in front :-)

Help

Join our discord for help or feedback!

xeol-io / xeol

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