Container images comprise a layered file system and associated metadata, as defined by the Open Container Initiative (OCI) specifications.
Container images often include several layers containing third-party software from:
Operating system distributions, such as Debian, Ubuntu or CentOS.
Application package managers, such as npm, pip and RubyGems.
What Snyk Container detects
When Snyk Container scans an image, using any of the available integrations, we first find the software installed in the image, including:
dpkg, rpm and apk operating systems packages.
Popular unmanaged software, ie. installed outside a package manager.
Application packages based on the presence of a manifest file.
Note: the container does not need to be run as Snyk reads the info from the file system; therefore, no container or foreign code needs to be run in order to successfully scan.
After we have the list of installed software, we look that up against our vulnerability database, which combines public sources with proprietary research.
Note: Snyk also supports images using packages from those distributions but without the associated package manager, such as Distroless images.
Unmanaged software
Some software components from upstream providers are not installed using a package manager, but are downloaded as executables from third-parties. Snyk uses file fingerprinting to detect versions of the following components:
Node.js
OpenJDK
Recurring scans
New vulnerabilities are disclosed continuously., Snyk can alert you to new vulnerabilities in your image as they are announced, even when your image software installed has not changed.
If you use an integration which saves a snapshot of the installed software on Snyk’s service, Snyk Container automatically rescans without accessing the image, alerting you to new vulnerabilities quicker.