f7c9793542
The lack thereof enables spoofing ActivityPub objects. A malicious user could upload fake activities as attachments and (if having access to remote search) trick local and remote fedi instances into fetching and processing it as a valid object. If uploads are hosted on the same domain as the instance itself, it is possible for anyone with upload access to impersonate(!) other users of the same instance. If uploads are exclusively hosted on a different domain, even the most basic check of domain of the object id and fetch url matching should prevent impersonation. However, it may still be possible to trick servers into accepting bogus users on the upload (sub)domain and bogus notes attributed to such users. Instances which later migrated to a different domain and have a permissive redirect rule in place can still be vulnerable. If — like Akkoma — the fetching server is overly permissive with redirects, impersonation still works. This was possible because Plug.Static also uses our custom MIME type mappings used for actually authentic AP objects. Provided external storage providers don’t somehow return ActivityStream Content-Types on their own, instances using those are also safe against their users being spoofed via uploads. Akkoma instances using the OnlyMedia upload filter cannot be exploited as a vector in this way — IF the fetching server validates the Content-Type of fetched objects (Akkoma itself does this already). However, restricting uploads to only multimedia files may be a bit too heavy-handed. Instead this commit will restrict the returned Content-Type headers for user uploaded files to a safe subset, falling back to generic 'application/octet-stream' for anything else. This will also protect against non-AP payloads as e.g. used in past frontend code injection attacks. It’s a slight regression in user comfort, if say PDFs are uploaded, but this trade-off seems fairly acceptable. (Note, just excluding our own custom types would offer no protection against non-AP payloads and bear a (perhaps small) risk of a silent regression should MIME ever decide to add a canonical extension for ActivityPub objects) Now, one might expect there to be other defence mechanisms besides Content-Type preventing counterfeits from being accepted, like e.g. validation of the queried URL and AP ID matching. Inserting a self-reference into our uploads is hard, but unfortunately *oma does not verify the id in such a way and happily accepts _anything_ from the same domain (without even considering redirects). E.g. Sharkey (and possibly other *keys) seem to attempt to guard against this by immediately refetching the object from its ID, but this is easily circumvented by just uploading two payloads with the ID of one linking to the other. Unfortunately *oma is thus _both_ a vector for spoofing and vulnerable to those spoof payloads, resulting in an easy way to impersonate our users. Similar flaws exists for emoji and media proxy. Subsequent commits will fix this by rigorously sanitising content types in more areas, hardening our checks, improving the default config and discouraging insecure config options. |
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| docs | ||
| installation | ||
| lib | ||
| priv | ||
| rel | ||
| restarter | ||
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| CHANGELOG.md | ||
| CODE_OF_CONDUCT.md | ||
| COPYING | ||
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| README.md | ||
| SECURITY.md | ||
| SIGNING_KEY.pub | ||
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README.md
akkoma
a smallish microblogging platform, aka the cooler pleroma
About
This is a fork of Pleroma, which is a microblogging server software that can federate (= exchange messages with) other servers that support ActivityPub. What that means is that you can host a server for yourself or your friends and stay in control of your online identity, but still exchange messages with people on larger servers. Akkoma will federate with all servers that implement ActivityPub, like Friendica, GNU Social, Hubzilla, Mastodon, Misskey, Peertube, and Pixelfed.
Akkoma is written in Elixir and uses PostgreSQL for data storage.
For clients it supports the Mastodon client API with Pleroma extensions (see the API section on https://docs.akkoma.dev/stable/).
Differences with Pleroma
Akkoma is a faster-paced fork, it has a varied and potentially experimental feature set tailored specifically to the corner of the fediverse inhabited by the project creator and contributors.
This should not be considered a one-for-one match with pleroma; it is more opinionated in many ways, and has a smaller community (which is good or bad depending on your view)
For example, Akkoma has:
- Custom Emoji reactions (compatible with misskey)
- Misskey-flavoured markdown support
- Elasticsearch and Meilisearch support for search
- Mastodon frontend (Glitch-Soc and Fedibird flavours) support
- Automatic post translation via DeepL or LibreTranslate
- A multitude of heavy modifications to the Pleroma Frontend (Pleroma-FE)
- The "bubble" concept, in which instance administrators can choose closely-related instances to make a "community of communities", so to say
And takes a more opinionated stance on issues like Domain blocks, which are enforced far more on Akkoma.
Take a look at the Changelog if you want a full list of recent changes, everything since 3.0 has been Akkoma.
Installation
OTP releases (Recommended)
If you are running Linux (glibc or musl) on x86, the recommended way to install Akkoma is by using OTP releases. OTP releases are as close as you can get to binary releases with Erlang/Elixir. The release is self-contained, and provides everything needed to boot it. The installation instructions are available here.
From Source
If your platform is not supported, or you just want to be able to edit the source code easily, you may install Akkoma from source.
Docker
Docker installation is supported via this setup
Packages
Akkoma is packaged for YunoHost and can be found and installed from the YunoHost app catalogue.
Compilation Troubleshooting
If you ever encounter compilation issues during the updating of Akkoma, you can try these commands and see if they fix things:
mix deps.clean --allmix local.rebarmix local.hexrm -r _build