Large file DoS in client partially mitigated

THREATQW57 · Partially mitigated: Some controls are in place, but the risk is still too high. · Defined in catalog.py:3812

Risk: Low impact × Medium likelihood = 3 low
After mitigations: Low impact × Low likelihood = 2 low

How statuses and scores work

Very large messages or replies can consume all memory in securedrop-client in sd-app

Mitigations

Mitigation	Status
Forms use WTForms validators MITIG51	implemented

Where it applies

Applies to 1 component in 2 scenarios.

sd-app (SecureDrop Client) Workstation VMs

Workstation: reading submissions · sd-app (SecureDrop Client)

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;

                style = "filled";

                fillcolor = "#c0392b";

                fontcolor = "white";

                class = "highlighted";
            ]

            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_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: export and print · sd-app (SecureDrop Client)

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

    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;

                style = "filled";

                fillcolor = "#c0392b";

                fontcolor = "white";

                class = "highlighted";
            ]

            component_sd_devices__export_and_print__Workstation_VMs [
                shape = circle;
                color = black;
                fontcolor = black;
                label = "sd-devices\n(export and\nprint)";
                URL = "component_sd_devices__export_and_print_.html";
                tooltip = "sd-devices (export and print)";
                margin = 0.02;
            ]

            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_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_usb_Workstation_VMs [
                shape = circle;
                color = black;
                fontcolor = black;
                label = "sys-usb";
                URL = "component_sys_usb.html";
                tooltip = "sys-usb";
                margin = 0.02;
            ]

        }

    }

    component_Export_Device_ [
        shape = circle;
        color = black;
        fontcolor = black;
        label = "Export Device";
        URL = "component_Export_Device.html";
        tooltip = "Export Device";
        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. Choose export";    ]
    component_sd_app__SecureDrop_Client__Workstation_VMs -> component_sd_devices__export_and_print__Workstation_VMs [        color = black;        fontcolor = black;        dir = forward;        label = "2. Hand file to\nexport VM";    ]
    component_sys_usb_Workstation_VMs -> component_sd_devices__export_and_print__Workstation_VMs [        color = black;        fontcolor = black;        dir = forward;        label = "3. Attach USB device";    ]
    component_sd_devices__export_and_print__Workstation_VMs -> component_Export_Device_ [        color = black;        fontcolor = black;        dir = forward;        label = "4. Write to drive";    ]
    component_sd_devices__export_and_print__Workstation_VMs -> component_sd_viewer__disposable_VMs__Workstation_VMs [        color = black;        fontcolor = black;        dir = forward;        label = "5. Preview in\ndisposable VM";    ]
    component_sd_devices__export_and_print__Workstation_VMs -> component_sd_log_Workstation_VMs [        color = black;        fontcolor = black;        dir = forward;        label = "6. Send logs";    ]
}

Notes

In scope for audit: No. Existing mitigations: Mitigated by MITIG51 in server side for source messages, not mitigated for replies. Replies though require a malicious journalist. Further mitigations: Also limit journalist reply size.

How this threat is matched

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