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docs(sbom): improve SBOM docs by adding a description for scanning SBOM attestation #2690

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Aug 10, 2022
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docs(sbom): improve SBOM docs by adding a description for scanning SBOM attestation #2690

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docs(sbom): improve SBOM docs by adding a description for scanning SB…
otms61 Aug 9, 2022
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docs: add a note on the example
otms61 Aug 10, 2022
f701954
docs: increase priority of descriptions for CycloneDX
otms61 Aug 10, 2022
8cb9cf8
docs: improve sbom attestation docs to add command example
otms61 Aug 10, 2022
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28 changes: 28 additions & 0 deletions docs/docs/attestation/sbom.md
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@@ -1,6 +1,7 @@
# SBOM attestation

[Cosign](https://github.com/sigstore/cosign) supports generating and verifying [in-toto attestations](https://github.com/in-toto/attestation). This tool enables you to sign and verify SBOM attestation.
And, Trivy can take an SBOM attestation as input and scan for vulnerabilities

!!! note
In the following examples, the `cosign` command will write an attestation to a target OCI registry, so you must have permission to write.
Expand Down Expand Up @@ -49,3 +50,30 @@ You can verify attestations.
```
$ COSIGN_EXPERIMENTAL=1 cosign verify-attestation <IMAGE>
```

## Scanning

Trivy can take an SBOM attestation as input and scan for vulnerabilities. Currently, Trivy supports CycloneDX-type attestation.

In the following example, Cosign can get an attestation and trivy scan it.

```bash
$ cosign verify-attestation --key /path/to/cosign.pub --type cyclonedx <IMAGE> > sbom.cdx.intoto.jsonl
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If it includes several attestations, Trivy fails to scan, right?

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The --type cyclonedx option of Cosign will take only cyclonedx attestation if the image has multiple attestations.
Depending on the number of cyclonedx attestations, the behavior will be as follows.

  • If there is no cycnlonedx attestation, the cosign command will fail.
  • If there is one cycnlonedx attestation, Trivy will successfully scan. This situation is assumed in the text of the description.
  • (rare case) If there is more than one cycnlonedx attestation, it will also successfully scan because json.NewReader parses only the first line if there are multiple lines in input data(ref). This is unintended behavior but it is not bad because they may be the same content.

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I've added a note that before trying the example, you create CycloneDX-type attestation.

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If there is more than one cycnlonedx attestation, it will also successfully scan because json.NewReader parses only the first line if there are multiple lines in input data(ref).

I didn't know that. Cool. Thanks for your explanation.

$ trivy sbom ./sbom.cdx.intoto.jsonl

sbom.cdx.intoto.jsonl (alpine 3.7.3)
=========================
Total: 2 (UNKNOWN: 0, LOW: 0, MEDIUM: 0, HIGH: 0, CRITICAL: 2)

┌────────────┬────────────────┬──────────┬───────────────────┬───────────────┬──────────────────────────────────────────────────────────┐
│ Library │ Vulnerability │ Severity │ Installed Version │ Fixed Version │ Title │
├────────────┼────────────────┼──────────┼───────────────────┼───────────────┼──────────────────────────────────────────────────────────┤
│ musl │ CVE-2019-14697 │ CRITICAL │ 1.1.18-r3 │ 1.1.18-r4 │ musl libc through 1.1.23 has an x87 floating-point stack │
│ │ │ │ │ │ adjustment im ...... │
│ │ │ │ │ │ https://avd.aquasec.com/nvd/cve-2019-14697 │
├────────────┤ │ │ │ │ │
│ musl-utils │ │ │ │ │ │
│ │ │ │ │ │ │
│ │ │ │ │ │ │
└────────────┴────────────────┴──────────┴───────────────────┴───────────────┴──────────────────────────────────────────────────────────┘
```