Contrast is a confidential-computing runtime for Kubernetes. In versions before 1.18.0, the guest kernel's ACPI/AML handling is vulnerable to an AML injection attack ("BadAML"). ACPI tables containing AML bytecode are passed from the untrusted host (QEMU) to the guest firmware (OVMF) and on to the Linux kernel, whose AML interpreter executes them. An attacker controlling the host — an assumed adversary in Contrast's threat model — can craft a table with malicious, Turing-complete AML bytecode that the guest kernel interprets with access to the full guest memory, including private pages, resulting in arbitrary code execution and disclosure or modification of confidential guest data. The issue affects the AMD SEV-SNP platforms Metal-QEMU-SNP and Metal-QEMU-SNP-GPU; Metal-QEMU-TDX is not affected because ACPI table contents are measured into RTMR 0 by OVMF on Intel TDX. Version v1.18.0 mitigates the attack by sandboxing the kernel AML interpreter so that it cannot read or write private memory pages. This weakness is not specific to Contrast but is generic to Confidential Computing setups that expose the ACPI interface to the host.

Contrast is a confidential-computing runtime for Kubernetes. In versions before 1.19.1, the Kata agent policies generated by the Contrast CLI contained a flaw in the CopyFile verification that allowed arbitrary writes to the guest root filesystem. A malicious process on the untrusted host able to connect to the Kata agent VSOCK could issue a series of CopyFile requests to overwrite security-critical files in the guest or trick the workload into disclosing sensitive data, effectively amounting to a full guest takeover. Users unable to upgrade can apply an equivalent rego policy fix passed to 'contrast generate --policy'.

Contrast is a confidential-computing runtime for Kubernetes. In versions before 1.4.1, a recovering Coordinator does not verify the seed supplied by the recovering party. An attacker can therefore stand up a rogue Coordinator whose manifest passes validation but whose secret seed is attacker-controlled. If network traffic is redirected from the legitimate Coordinator to the attacker's Coordinator, a workload owner can be impersonated when they either set a new manifest without comparing the returned root CA certificate against the existing one (the default behavior of the contrast CLI) or verify the Coordinator without comparing the root CA certificate against a trusted reference. Under these conditions the attacker can issue certificates that chain back to the rogue Coordinator's root CA and recover arbitrary workload secrets of workloads deployed after the attack. Secrets of the legitimate Coordinator (seed, workload secrets, CA), workload integrity, and certificates chaining to the mesh CA are not affected.