Cosign vulnerable to system-wide denial of service via malicious attachments

Summary

Cosign provides code signing and transparency for containers and binaries. Prior to version 2.2.4, a remote image with a malicious attachment can cause denial of service of the host machine running Cosign. This can impact other services on the machine that rely on having memory available such as a Redis database which can result in data loss. It can also impact the availability of other services on the machine that will not be available for the duration of the machine denial. The root cause of this issue is that Cosign reads the attachment from a remote image entirely into memory without checking the size of the attachment first. As such, a large attachment can make Cosign read a large attachment into memory; If the attachments size is larger than the machine has memory available, the machine will be denied of service. The Go runtime will make a SigKill after a few seconds of system-wide denial. This issue can allow a supply-chain escalation from a compromised registry to the Cosign user: If an attacher has compromised a registry or the account of an image vendor, they can include a malicious attachment and hurt the image consumer. Version 2.2.4 contains a patch for the vulnerability.

Timeline

1. Apr 10, 2024, 10:28 PM UTCCVE published
2. Jun 3, 2024, 2:13 PM UTCCISA SSVC assessment

   Exploitation: poc · Automatable: no · Technical impact: partial

3. Aug 2, 2024, 1:17 AM UTCRecord last updated

Affected versions

• sigstore cosign

  fixed in 2.2.4

• github.com/sigstore/cosignGo

  through 2.2.3

• github.com/sigstore/cosign/v2Go

  fixed in 2.2.4

• github.com/sigstore/cosignGo

  All versions

References 5