CPU-based attacks accepted

THREATQW12 · Accepted: The team has decided to live with this risk. · Defined in catalog.py:3171

Risk: High impact × Very Low likelihood = 3 low
After mitigations: High impact × Very Low likelihood = 3 low (unchanged)

An attacker with code execution on any VM on the workstation could exploit vulnerabilities in the CPU and obtain code execution in dom0 or another VM.

Threat actors: Nation State / Law Enforcement

Mitigations

Mitigation	Status
Disabling hyperthreading (done by Qubes) MITIGQW35	implemented

Residual risk

Unknown CPU vulnerabilities may expose VMs to side-channel attacks

Where it applies

Applies to 1 component in 1 scenario.

Workstation hardware SecureDrop Workstation

Workstation: boot, provisioning and updates · Workstation hardware

digraph tm {
    graph [
        fontname = Arial;
        fontsize = 14;
    ]
    node [
        fontname = Arial;
        fontsize = 14;
    ]
    edge [
        fontname = Arial;
        fontsize = 12;
    ]
    nodesep = 1;

    subgraph cluster_boundary_External_Services {
        graph [
            fontsize = 10;
            fontcolor = black;
            style = dashed;
            color = firebrick2;
            label = <<i>External Services</i>>;
        ]

        component_FPF_apt_repository_External_Services [
            shape = circle;
            color = black;
            fontcolor = black;
            label = "FPF apt\nrepository";
            URL = "component_FPF_apt_repository.html";
            tooltip = "FPF apt repository";
            margin = 0.02;
        ]

    }

    subgraph cluster_boundary_SecureDrop_Workstation {
        graph [
            fontsize = 10;
            fontcolor = black;
            style = dashed;
            color = firebrick2;
            label = <<i>SecureDrop Workstation</i>>;
        ]

        subgraph cluster_boundary_Workstation_VMs {
            graph [
                fontsize = 10;
                fontcolor = black;
                style = dashed;
                color = firebrick2;
                label = <<i>Workstation VMs</i>>;
            ]

            component_sd_gpg_Workstation_VMs [
                shape = circle;
                color = black;
                fontcolor = black;
                label = "sd-gpg";
                URL = "component_sd_gpg.html";
                tooltip = "sd-gpg";
                margin = 0.02;
            ]

        }

        component_Qubes_OS_and_Xen_SecureDrop_Workstation [
            shape = circle;
            color = black;
            fontcolor = black;
            label = "Qubes OS and Xen";
            URL = "component_Qubes_OS_and_Xen.html";
            tooltip = "Qubes OS and Xen";
            margin = 0.02;
        ]

        component_Workstation_bootloader_SecureDrop_Workstation [
            shape = circle;
            color = black;
            fontcolor = black;
            label = "Workstation\nbootloader";
            URL = "component_Workstation_bootloader.html";
            tooltip = "Workstation bootloader";
            margin = 0.02;
        ]

        component_Workstation_firmware_SecureDrop_Workstation [
            shape = circle;
            color = black;
            fontcolor = black;
            label = "Workstation\nfirmware";
            URL = "component_Workstation_firmware.html";
            tooltip = "Workstation firmware";
            margin = 0.02;
        ]

        component_Workstation_hardware_SecureDrop_Workstation [
            shape = circle;
            color = black;
            fontcolor = black;
            label = "Workstation\nhardware";
            URL = "component_Workstation_hardware.html";
            tooltip = "Workstation hardware";
            margin = 0.02;

            style = "filled";

            fillcolor = "#c0392b";

            fontcolor = "white";

            class = "highlighted";
        ]

        component_Workstation_provisioning_code_SecureDrop_Workstation [
            shape = circle;
            color = black;
            fontcolor = black;
            label = "Workstation\nprovisioning\ncode";
            URL = "component_Workstation_provisioning_code.html";
            tooltip = "Workstation provisioning code";
            margin = 0.02;
        ]

        component_dom0_SecureDrop_Workstation [
            shape = circle;
            color = black;
            fontcolor = black;
            label = "dom0";
            URL = "component_dom0.html";
            tooltip = "dom0";
            margin = 0.02;
        ]

    }

    actor_Administrator_ [
        shape = square;
        color = black;
        fontcolor = black;
        label = "Administrator";
        URL = "component_Administrator.html";
        tooltip = "Administrator";
        margin = 0.02;
    ]

    actor_Journalist_ [
        shape = square;
        color = black;
        fontcolor = black;
        label = "Journalist";
        URL = "component_Journalist.html";
        tooltip = "Journalist";
        margin = 0.02;
    ]

    actor_Journalist_ -> component_Workstation_hardware_SecureDrop_Workstation [        color = black;        fontcolor = black;        dir = forward;        label = "1. Power on";    ]
    component_Workstation_hardware_SecureDrop_Workstation -> component_Workstation_firmware_SecureDrop_Workstation [        color = black;        fontcolor = black;        dir = forward;        label = "2. Start firmware";    ]
    component_Workstation_firmware_SecureDrop_Workstation -> component_Workstation_bootloader_SecureDrop_Workstation [        color = black;        fontcolor = black;        dir = forward;        label = "3. Load bootloader";    ]
    component_Workstation_bootloader_SecureDrop_Workstation -> component_Qubes_OS_and_Xen_SecureDrop_Workstation [        color = black;        fontcolor = black;        dir = forward;        label = "4. Boot Qubes";    ]
    component_Qubes_OS_and_Xen_SecureDrop_Workstation -> component_dom0_SecureDrop_Workstation [        color = black;        fontcolor = black;        dir = forward;        label = "5. Start dom0";    ]
    actor_Administrator_ -> component_Workstation_provisioning_code_SecureDrop_Workstation [        color = black;        fontcolor = black;        dir = forward;        label = "6. Install and\nconfigure";    ]
    component_Workstation_provisioning_code_SecureDrop_Workstation -> component_dom0_SecureDrop_Workstation [        color = black;        fontcolor = black;        dir = forward;        label = "7. Apply salt states";    ]
    component_dom0_SecureDrop_Workstation -> component_sd_gpg_Workstation_VMs [        color = black;        fontcolor = black;        dir = forward;        label = "8. Provide secret\nkeys";    ]
    component_dom0_SecureDrop_Workstation -> component_FPF_apt_repository_External_Services [        color = black;        fontcolor = black;        dir = forward;        label = "9. Fetch updates";    ]
    component_FPF_apt_repository_External_Services -> component_dom0_SecureDrop_Workstation [        color = black;        fontcolor = black;        dir = forward;        label = "10. Signed packages";    ]
}

Notes

In scope for audit: No. Existing mitigations: Host (Qubes) and Guest kernels have mitigations=full and nosmt=on (MITIGQW35). Further mitigations: - Disable Hyperthreading at the BIOS-level.

How this threat is matched

Listed for these components. A boundary covers every component inside it.