The Machine With Many Faces: Post-Exploitation Identity Misuse in SPIFFE/SPIRE

This research demonstrates post-exploitation techniques that could allow an attacker with root access on a compromised Kubernetes node to misuse an open standard and reference implementation for machine identity known as SPIFFE/SPIRE to impersonate co-located workloads and harvest SPIFFE Verifiable Identity Documents (SVIDs). We show how the trust assumption at the core of every machine-identity system — that the node is trusted — collapses once an attacker obtains root on that node. Unit 42 has not observed this technique exploited in the wild.

The Secure Production Identity Framework for Everyone (SPIFFE)/the SPIFFE Runtime Environment (SPIRE) is widely deployed in Kubernetes and cloud-native environments to replace long-lived secrets with short-lived, cryptographically verifiable workload identities.

Our research shows how an attacker with root can spoof the Linux control group (cgroup) information the SPIRE agent uses during workload attestation. This tricks the agent into issuing a co-located workload's SVID to an attacker-controlled process.

As part of this research, we developed Spooffe, an open-source tool that defenders can use to test whether an attacker with administrative access could manipulate cgroup metadata to retrieve co-located workload identities and assess the resulting identity area of impact.

When designing threat models for SPIFFE/SPIRE, organizations should assume that root-level access to a node grants access to all cryptographic identities scoped to it. We recommend performing the following activities to reduce exposure:

Palo Alto Networks customers are better protected from the threats described here through the following products and services:

If you think you might have been compromised or have an urgent matter, contact the Unit 42 Incident Response team.