SecureDrop APT servers are compromised or APT server man-in-the middle attack with malicious packages. mitigated

THREAT54 · Mitigated: Controls in place bring the risk down to an acceptable level. · Defined in catalog.py:960

Risk: High impact × Low likelihood = 6 medium
After mitigations: High impact × Very Low likelihood = 3 low

An adversary that compromises APT server could serve potentially malcious .deb files (securedrop*, tor, or Linux image packages)

Threat actors: Nation State / Law Enforcement Large Corporation ISP

Mitigations

Mitigation	Status
All SecureDrop and tor releases (Release file and tag) signed with airgapped key MITIG46	implemented
tag verified before building debian packages MITIG227	implemented

Residual risk

Hash collision

Where it applies

Applies to 1 component in 3 scenarios.

FPF apt repository External Services

Updates, time & DNS · FPF apt repository

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_App_Server_APT_NTP_DNS_Application_Server [
            shape = circle;
            color = black;
            fontcolor = black;
            label = "App Server\nAPT/NTP/DNS";
            URL = "component_App_Server_APT_NTP_DNS.html";
            tooltip = "App Server APT/NTP/DNS";
            margin = 0.02;
        ]

    }

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

        component_DNS_resolver_External_Services [
            shape = circle;
            color = black;
            fontcolor = black;
            label = "DNS resolver";
            URL = "component_DNS_resolver.html";
            tooltip = "DNS resolver";
            margin = 0.02;
        ]

        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;

            style = "filled";

            fillcolor = "#c0392b";

            fontcolor = "white";

            class = "highlighted";
        ]

        component_NTP_server_External_Services [
            shape = circle;
            color = black;
            fontcolor = black;
            label = "NTP server";
            URL = "component_NTP_server.html";
            tooltip = "NTP server";
            margin = 0.02;
        ]

        component_Ubuntu_apt_repository_External_Services [
            shape = circle;
            color = black;
            fontcolor = black;
            label = "Ubuntu apt\nrepository";
            URL = "component_Ubuntu_apt_repository.html";
            tooltip = "Ubuntu apt repository";
            margin = 0.02;
        ]

    }

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

        component_Monitor_Server_APT_NTP_DNS_Monitoring_Server [
            shape = circle;
            color = black;
            fontcolor = black;
            label = "Monitor Server\nAPT/NTP/DNS";
            URL = "component_Monitor_Server_APT_NTP_DNS.html";
            tooltip = "Monitor Server APT/NTP/DNS";
            margin = 0.02;
        ]

    }

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

        component_Dedicated_Hardware_Firewall_SecureDrop_Area [
            shape = circle;
            color = black;
            fontcolor = black;
            label = "Dedicated\nHardware\nFirewall";
            URL = "component_Dedicated_Hardware_Firewall.html";
            tooltip = "Dedicated Hardware Firewall";
            margin = 0.02;
        ]

    }

    component_App_Server_APT_NTP_DNS_Application_Server -> component_Monitor_Server_APT_NTP_DNS_Monitoring_Server [        color = black;        fontcolor = black;        dir = forward;        label = "1. Proxy via monitor";    ]
    component_Monitor_Server_APT_NTP_DNS_Monitoring_Server -> component_Dedicated_Hardware_Firewall_SecureDrop_Area [        color = black;        fontcolor = black;        dir = forward;        label = "2. Egress via\nfirewall";    ]
    component_Dedicated_Hardware_Firewall_SecureDrop_Area -> component_Ubuntu_apt_repository_External_Services [        color = black;        fontcolor = black;        dir = forward;        label = "3. Ubuntu apt";    ]
    component_Dedicated_Hardware_Firewall_SecureDrop_Area -> component_FPF_apt_repository_External_Services [        color = black;        fontcolor = black;        dir = forward;        label = "4. FPF apt";    ]
    component_Dedicated_Hardware_Firewall_SecureDrop_Area -> component_NTP_server_External_Services [        color = black;        fontcolor = black;        dir = forward;        label = "5. NTP";    ]
    component_Dedicated_Hardware_Firewall_SecureDrop_Area -> component_DNS_resolver_External_Services [        color = black;        fontcolor = black;        dir = forward;        label = "6. DNS";    ]
}

Supply chain and dependencies · FPF apt repository

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_App_Server_APT_NTP_DNS_Application_Server [
            shape = circle;
            color = black;
            fontcolor = black;
            label = "App Server\nAPT/NTP/DNS";
            URL = "component_App_Server_APT_NTP_DNS.html";
            tooltip = "App Server APT/NTP/DNS";
            margin = 0.02;
        ]

        component_Source_Interface_Application_Server [
            shape = circle;
            color = black;
            fontcolor = black;
            label = "Source Interface";
            URL = "component_Source_Interface.html";
            tooltip = "Source Interface";
            margin = 0.02;
        ]

    }

    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;

            style = "filled";

            fillcolor = "#c0392b";

            fontcolor = "white";

            class = "highlighted";
        ]

        component_SecureDrop_release___package_build_External_Services [
            shape = circle;
            color = black;
            fontcolor = black;
            label = "SecureDrop\nrelease &\npackage build";
            URL = "component_SecureDrop_release___package_build.html";
            tooltip = "SecureDrop release & package build";
            margin = 0.02;
        ]

        component_SecureDrop_source_repository_External_Services [
            shape = circle;
            color = black;
            fontcolor = black;
            label = "SecureDrop\nsource\nrepository";
            URL = "component_SecureDrop_source_repository.html";
            tooltip = "SecureDrop source repository";
            margin = 0.02;
        ]

        component_Tor_software_External_Services [
            shape = circle;
            color = black;
            fontcolor = black;
            label = "Tor software";
            URL = "component_Tor_software.html";
            tooltip = "Tor software";
            margin = 0.02;
        ]

        component_Ubuntu_apt_repository_External_Services [
            shape = circle;
            color = black;
            fontcolor = black;
            label = "Ubuntu apt\nrepository";
            URL = "component_Ubuntu_apt_repository.html";
            tooltip = "Ubuntu apt repository";
            margin = 0.02;
        ]

    }

    component_SecureDrop_source_repository_External_Services -> component_SecureDrop_release___package_build_External_Services [        color = black;        fontcolor = black;        dir = forward;        label = "1. Build from source";    ]
    component_SecureDrop_release___package_build_External_Services -> component_FPF_apt_repository_External_Services [        color = black;        fontcolor = black;        dir = forward;        label = "2. Publish packages";    ]
    component_FPF_apt_repository_External_Services -> component_App_Server_APT_NTP_DNS_Application_Server [        color = black;        fontcolor = black;        dir = forward;        label = "3. Install / update";    ]
    component_Ubuntu_apt_repository_External_Services -> component_App_Server_APT_NTP_DNS_Application_Server [        color = black;        fontcolor = black;        dir = forward;        label = "4. Ubuntu\ndependencies";    ]
    component_Tor_software_External_Services -> component_Source_Interface_Application_Server [        color = black;        fontcolor = black;        dir = forward;        label = "5. Tor dependency";    ]
}

Workstation: boot, provisioning and updates · FPF apt repository

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;

            style = "filled";

            fillcolor = "#c0392b";

            fontcolor = "white";

            class = "highlighted";
        ]

    }

    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;
        ]

        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: SecureDrop updates are packaged in a .deb file and served through FPF's apt repo. Release files containing hashes (MD5, SHA1, SHA256, SHA512) of Package file and package hashes are signed with an airgapped GPG key. Source code is validated/verified before packaging and signing the .deb. (MITIG46, MITIG227). Automated test for mitigation: No.

How this threat is matched

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