Scenario: release_sandbox

Build and sign sandbox threat model

Findings

Data Flows

Affected Components

Data Flow Diagram

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

    subgraph cluster_boundary_FPF_operated_Tailnet {
        graph [
            fontsize = 10;
            fontcolor = black;
            style = dashed;
            color = firebrick2;
            label = <FPF-operated Tailnet>;
        ]

        server_Build_machines_FPF_operated_Tailnet [
            shape = box;
            color = black;
            fontcolor = black;
            label = "Build machines";
            URL = "component_Build_machines.html";
            tooltip = "Build machines";
            margin = 0.02;
        ]

        component_Cosign_Binary__build_machines__FPF_operated_Tailnet [
            shape = circle;
            color = black;
            fontcolor = black;
            label = "Cosign Binary\n(build machines)";
            URL = "component_Cosign_Binary__build_machines_.html";
            tooltip = "Cosign Binary (build machines)";
            margin = 0.02;
        ]

    }

    subgraph cluster_boundary_Internet {
        graph [
            fontsize = 10;
            fontcolor = black;
            style = dashed;
            color = firebrick2;
            label = <Internet>;
        ]

        externalentity_GitHub_Container_Registry_Internet [
            shape = square;
            color = black;
            fontcolor = black;
            label = "GitHub Container\nRegistry";
            URL = "component_GitHub_Container_Registry.html";
            tooltip = "GitHub Container Registry";
            margin = 0.02;
        ]

        externalentity_Rekor_Log_Server_Internet [
            shape = square;
            color = black;
            fontcolor = black;
            label = "Rekor Log Server";
            URL = "component_Rekor_Log_Server.html";
            tooltip = "Rekor Log Server";
            margin = 0.02;
        ]

    }

    server_Build_machines_FPF_operated_Tailnet -> externalentity_GitHub_Container_Registry_Internet [        color = black;        fontcolor = black;        dir = forward;        label = "1. Build container\nimage";    ]
    server_Build_machines_FPF_operated_Tailnet -> externalentity_GitHub_Container_Registry_Internet [        color = black;        fontcolor = black;        dir = forward;        label = "2. Push container to\nGHCR";    ]
    component_Cosign_Binary__build_machines__FPF_operated_Tailnet -> externalentity_GitHub_Container_Registry_Internet [        color = black;        fontcolor = black;        dir = forward;        label = "3. Sign remote\nsandbox image";    ]
    component_Cosign_Binary__build_machines__FPF_operated_Tailnet -> externalentity_Rekor_Log_Server_Internet [        color = black;        fontcolor = black;        dir = forward;        label = "4. Publish rekor\nlogs";    ]
    server_Build_machines_FPF_operated_Tailnet -> externalentity_GitHub_Container_Registry_Internet [        color = black;        fontcolor = black;        dir = forward;        label = "5. Request signed\nsandbox tarball";    ]
    externalentity_GitHub_Container_Registry_Internet -> server_Build_machines_FPF_operated_Tailnet [        color = black;        fontcolor = black;        dir = forward;        label = "6. Response with the\nsigned sandbox +\nsignatures";    ]
    server_Build_machines_FPF_operated_Tailnet -> component_Cosign_Binary__build_machines__FPF_operated_Tailnet [        color = black;        fontcolor = black;        dir = forward;        label = "7. Generate the\nsandbox tarball from\nthe pulled container\nimage";    ]
    server_Build_machines_FPF_operated_Tailnet -> externalentity_GitHub_Container_Registry_Internet [        color = black;        fontcolor = black;        dir = forward;        label = "8. Tag remote\nsandbox";    ]
}

Sequence Diagram

sequenceDiagram
    participant Build_machines as Build machines
    link Build_machines: Component @ component_Build_machines.html
    participant GitHub_Container_Registry as GitHub Container Registry
    link GitHub_Container_Registry: Component @ component_GitHub_Container_Registry.html
    participant Cosign_Binary__build_machines_ as Cosign Binary (build machines)
    link Cosign_Binary__build_machines_: Component @ component_Cosign_Binary__build_machines_.html
    participant Rekor_Log_Server as Rekor Log Server
    link Rekor_Log_Server: Component @ component_Rekor_Log_Server.html

    Build_machines->>GitHub_Container_Registry: 1. Build container image
    Build_machines->>GitHub_Container_Registry: 2. Push container to GHCR
    Cosign_Binary__build_machines_->>GitHub_Container_Registry: 3. Sign remote sandbox image
    Cosign_Binary__build_machines_->>Rekor_Log_Server: 4. Publish rekor logs
    Build_machines->>GitHub_Container_Registry: 5. Request signed sandbox tarball
    GitHub_Container_Registry->>Build_machines: 6. Response with the signed sandbox + signatures
    Build_machines->>Cosign_Binary__build_machines_: 7. Generate the sandbox tarball from the pulled container image
    Build_machines->>GitHub_Container_Registry: 8. Tag remote sandbox

Show data flows

ID	Name	Source	Sink	Type
1	Build container image	Build machines	GitHub Container Registry	Request
2	Push container to GHCR	Build machines	GitHub Container Registry	Request
3	Sign remote sandbox image	Cosign Binary (build machines)	GitHub Container Registry	Request
4	Publish rekor logs	Cosign Binary (build machines)	Rekor Log Server	Request
5	Request signed sandbox tarball	Build machines	GitHub Container Registry	Request
6	Response with the signed sandbox + signatures	GitHub Container Registry	Build machines	Request
7	Generate the sandbox tarball from the pulled container image	Build machines	Cosign Binary (build machines)	Request
8	Tag remote sandbox	Build machines	GitHub Container Registry	Request

Applicable threats

Threat ID	Description	Target Component	Mitigations
DZ-1-DEPS		Build machines	verifies resources.deps
DZ-4		Sandbox Private Key	is physical
CAPEC-23	File Content Injection	Cosign Binary (build machines)	is sandboxed
CAPEC-28	Fuzzing	Cosign Binary (build machines)	sanitizes input is fuzzed
CAPEC-40	Manipulating Writeable Terminal Devices	Cosign Binary (build machines)	sanitizes input
CAPEC-113	Interface Manipulation	Cosign Binary (build machines)	sanitizes input is sandboxed
CAPEC-130	Excessive Allocation	Cosign Binary (build machines)	is resource constrained sanitizes input
CAPEC-131	Resource Leak Exposure	Cosign Binary (build machines)	is resource constrained
CAPEC-145	Checksum Spoofing	Build machines	uses strong crypto
CAPEC-165	File Manipulation	Cosign Binary (build machines)	is sandboxed sanitizes input
CAPEC-276	Inter-component Protocol Manipulation	Cosign Binary (build machines)	is sandboxed sanitizes input
CAPEC-440	Hardware Integrity Attack	Build machines	is verifiable
CAPEC-473	Signature Spoof	Build machines	uses strong crypto
CAPEC-582	Route Disabling	GitHub Container Registry	works offline
CAPEC-582	Route Disabling	Build machines	works offline
CAPEC-582	Route Disabling	Remote Sandbox Image	works offline
CAPEC-582	Route Disabling	Cosign Binary (build machines)	works offline
CAPEC-582	Route Disabling	Rekor Log Server	works offline
CAPEC-639	Probe System Files	GitHub Container Registry	is sandboxed
CAPEC-639	Probe System Files	DZ container image	is sandboxed
CAPEC-639	Probe System Files	Remote Sandbox Image	is sandboxed
CAPEC-639	Probe System Files	Cosign Binary (build machines)	is sandboxed
CAPEC-639	Probe System Files	Sandbox Signature Data	is sandboxed
CAPEC-639	Probe System Files	Rekor Log Server	is sandboxed
CAPEC-639	Probe System Files	Embedded Sandbox	is sandboxed

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