GPG VM (sd-gpg) performs attacker file decryption mitigated

THREATQW7 · Mitigated: Controls in place bring the risk down to an acceptable level. · Defined in catalog.py:3084

Risk: High impact × Low likelihood = 6 medium
After mitigations: Low impact × Low likelihood = 2 low

An attacker with control of a VM that has access to the sd-gpg vm may arbitrarily decrypt files by requesting the GPG VM to decrypt.

Threat actors: Nation State / Law Enforcement

Mitigations

No mitigations in place.

Possible further mitigations

Use hardware token to store submission key MITIGQW8 proposed
Default Qubes-RPC deny policy MITIGQW15 implemented
Sanitize/validate GPG payload in sd-svs prior to sending to sd-gpg (https://github.com/freedomofpress/securedrop-client/issues/433) MITIGQW16 proposed

Where it applies

Applies to 1 component in 2 scenarios.

sd-gpg Workstation VMs

Workstation: reading submissions · sd-gpg

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

    subgraph cluster_boundary_Application_Server {
        graph [
            fontsize = 10;
            fontcolor = black;
            style = dashed;
            color = firebrick2;
            label = <<i>Application Server</i>>;
        ]

        component_Journalist_Interface_Application_Server [
            shape = circle;
            color = black;
            fontcolor = black;
            label = "Journalist\nInterface";
            URL = "component_Journalist_Interface.html";
            tooltip = "Journalist Interface";
            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_app__SecureDrop_Client__Workstation_VMs [
                shape = circle;
                color = black;
                fontcolor = black;
                label = "sd-app\n(SecureDrop\nClient)";
                URL = "component_sd_app__SecureDrop_Client_.html";
                tooltip = "sd-app (SecureDrop Client)";
                margin = 0.02;
            ]

            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;

                style = "filled";

                fillcolor = "#c0392b";

                fontcolor = "white";

                class = "highlighted";
            ]

            component_sd_log_Workstation_VMs [
                shape = circle;
                color = black;
                fontcolor = black;
                label = "sd-log";
                URL = "component_sd_log.html";
                tooltip = "sd-log";
                margin = 0.02;
            ]

            component_sd_proxy_Workstation_VMs [
                shape = circle;
                color = black;
                fontcolor = black;
                label = "sd-proxy";
                URL = "component_sd_proxy.html";
                tooltip = "sd-proxy";
                margin = 0.02;
            ]

            component_sd_viewer__disposable_VMs__Workstation_VMs [
                shape = circle;
                color = black;
                fontcolor = black;
                label = "sd-viewer\n(disposable VMs)";
                URL = "component_sd_viewer__disposable_VMs_.html";
                tooltip = "sd-viewer (disposable VMs)";
                margin = 0.02;
            ]

            component_sys_firewall_Workstation_VMs [
                shape = circle;
                color = black;
                fontcolor = black;
                label = "sys-firewall";
                URL = "component_sys_firewall.html";
                tooltip = "sys-firewall";
                margin = 0.02;
            ]

            component_sys_net_Workstation_VMs [
                shape = circle;
                color = black;
                fontcolor = black;
                label = "sys-net";
                URL = "component_sys_net.html";
                tooltip = "sys-net";
                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_sd_app__SecureDrop_Client__Workstation_VMs [        color = black;        fontcolor = black;        dir = forward;        label = "1. Use the client";    ]
    component_sd_app__SecureDrop_Client__Workstation_VMs -> component_sd_proxy_Workstation_VMs [        color = black;        fontcolor = black;        dir = forward;        label = "2. Journalist API\nrequest";    ]
    component_sd_proxy_Workstation_VMs -> component_sys_firewall_Workstation_VMs [        color = black;        fontcolor = black;        dir = forward;        label = "3. Route via\nfirewall";    ]
    component_sys_firewall_Workstation_VMs -> component_sys_net_Workstation_VMs [        color = black;        fontcolor = black;        dir = forward;        label = "4. Route to network";    ]
    component_sys_net_Workstation_VMs -> component_Journalist_Interface_Application_Server [        color = black;        fontcolor = black;        dir = forward;        label = "5. Reach the\nJournalist Interface";    ]
    component_Journalist_Interface_Application_Server -> component_sys_net_Workstation_VMs [        color = black;        fontcolor = black;        dir = forward;        label = "6. Encrypted\nsubmissions";    ]
    component_sd_proxy_Workstation_VMs -> component_sd_app__SecureDrop_Client__Workstation_VMs [        color = black;        fontcolor = black;        dir = forward;        label = "7. Relay to client";    ]
    component_sd_app__SecureDrop_Client__Workstation_VMs -> component_sd_gpg_Workstation_VMs [        color = black;        fontcolor = black;        dir = forward;        label = "8. Decrypt";    ]
    component_sd_app__SecureDrop_Client__Workstation_VMs -> component_sd_viewer__disposable_VMs__Workstation_VMs [        color = black;        fontcolor = black;        dir = forward;        label = "9. Open a file";    ]
    component_sd_app__SecureDrop_Client__Workstation_VMs -> component_sd_log_Workstation_VMs [        color = black;        fontcolor = black;        dir = forward;        label = "10. Send logs";    ]
}

Workstation: boot, provisioning and updates · sd-gpg

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;

                style = "filled";

                fillcolor = "#c0392b";

                fontcolor = "white";

                class = "highlighted";
            ]

        }

        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;
        ]

        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

Existing mitigations: Qubes RPC policy restricts GPG access to the sd-svs VM exclusively. All other requests from other domains are denied by default. Further mitigations: Qubes can always ask for permission to decrypt. Enable passphrase for GPG key, move GPG key on physical token (MITIGQW8), Qubes RPC policy to deny (MITIGQW15), Validate GPG payload (MITIGQW16).

How this threat is matched

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