forgejo/docs/unsure-where-to-put/threat_analysis_star_activity.md

Threat analysis for the federated star activity

Technical Background

Control Flow

sequenceDiagram
    participant fs as foreign_repository_server
    participant os as our_repository_server

    fs ->> os: post /api/activitypub/repository-id/1/inbox {Start-Activity}
    activate os
    os ->> os: validate request inputs
    activate repository
    os ->> repository: validate
    repository ->> repository: search for reop with object-id
    deactivate repository
    activate person
    os ->> person: validate
    person ->> person: search for ser with actor-id
    person ->> fs: get /api/activitypub/user-id/{id from actor}
    person ->> person: create user from response
    deactivate person
    os ->> repository: execute star action
    os -->> fs: 200 ok
    deactivate os

Data transfered

# edn notation
{@context [
    "as":    "https://www.w3.org/ns/activitystreams#",
    "forge": "https://forgefed.org/ns#",],
  ::as/id "https://repo.prod.meissa.de/api/v1/activitypub/user-id/1/outbox/12345",
  ::as/type "Star",
  ::forge/source "forgejo",
  ::as/actor "https://repo.prod.meissa.de/api/v1/activitypub/user-id/1",
  ::as/object "https://codeberg.org/api/v1/activitypub/repository-id/12"
}

# json notation
{"id": "https://repo.prod.meissa.de/api/v1/activitypub/user-id/1/outbox/12345",
  "type": "Star",
  "source": "forgejo",
  "actor": "https://repo.prod.meissa.de/api/v1/activitypub/user-id/1",
  "object": "https://codeberg.org/api/v1/activitypub/repository-id/1"
}

Data Flow

flowchart TD
    A(User) --> |stars a federated repository| B(foreign repository server)
    B --> |Star Activity| C(our repository server)
    C --> |get repository localy| D(our repos database)
	C --> |get Person Actor| B
    C --> |create federated user localy| D
    C --> |add star to repo localy| D    

Analysis

Assets

1. Service Availability: The availability of our or foreign servers.
2. Reputation: Our standing against freinds and others.

Actors

1. Script Kiddies: Boored teens, willing to do some illigal without deep knowlege of tech details but broad knowlege across internet discussions. Able to do some bash / python scripting.
2. Experienced Hacker: Hacker with deep knowlege.

Threat

1. Script Kiddi sends a Star Activity containing an attack actor url http://attacked.target/very/special/path in place of actor. Our repository server sends an get Person Actor request to this url. The attacked target gets DenialdOffServices. We loose CPU & reputation.
2. Experienced hacker sends a Star Activity containing an actor url pointing to an evil forgejo instance. Our repository server sends an get Person Actor request to this instance and get a person having sth. like ; drop database; in its name. If our server tries to create a new user out of this persion, the db might be droped.

DREAD-Score

Threat	Damage	Reproducibility	Exploitability	Affected Users	Discoverability	Mitigations
1.	... tbd
2.	... tbd

Bewertet wird mit Schulnoten von 1 - 6

• Damage – wie groß wäre der Schaden, wenn der Angriff erfolgreich ist? 6 ist ein sehr schlimmer Schaden.
• Reproducibility – wie einfach wäre der Angriff reproduzierbar? 6 ist sehr einfach zu reproduzieren.
• Exploitability – wieviel Zeit, Aufwand und Erfahrung sind notwendig, um die Bedrohung auszunutzen? 6 ist sehr einfach zu machen.
• Affected Users – wenn eine Bedrohung ausgenutzt werden würde, wieviel Prozent der Benutzer wären betroffen?
• Discoverability – Wie einfach lässt sich ein Angriff entdecken? Muss der Angreifer Strafverfolgung erwarten? 6 ist sehr schwer zu entdecken / ist gar nicht illegal

Reference

• https://geballte-sicherheit.de/threat-modelling-bedrohungsanalyse-7-teil-einstufung-von-bedrohungen-ranking-of-threats/