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Security Advisories: GSA_kwCzR0hTQS1tOTc0LXhqNGotN3F2Nc4AAzSd
Boxo bitswap/server: DOS unbounded persistent memory leak
Impact
An attacker is able allocate arbitrarily many bytes in the Bitswap server by sending many WANT_BLOCK
and or WANT_HAVE
requests which are queued in an unbounded queue, with allocations that persist even if the connection is closed.
This affects users accepting untrusted connections with the Bitswap server, this also affects users using the old API stubs at github.com/ipfs/boxo/bitswap
because it transitively uses github.com/ipfs/boxo/bitswap/server
.
We have renamed go-libipfs to boxo; this document uses both terms interchangeably. The version numbers for both are applicable, as they share the same historical timeline.
Remediation
Apply one of:
- Update
boxo
tov0.6.0
or later - Update
boxo
tov0.4.1
Note thatv0.5.0
is NOT safe,v0.4.1
is a backport of thev0.6.0
security fixes on top ofv0.4.0
.
Mitigations
- The server now limits how many wantlist entries per peer it knows.
TheMaxQueuedWantlistEntriesPerPeer
option allows configuring how many wantlist entries the server remembers; if a peer sends a wantlist bigger than this (including a sum of multiple delta updates) the server will truncate the wantlist to the match the limit.
This defaults to1024
entries per peer. - The server now properly clears state about peers when they disconnect.
Peer state is more lazily allocated (only when a wantlist is received in the first place) and is properly cleared when thePeerDisconnected
callback is received. - The server now ignores CIDs above some size.
Clients were able to send any CID as long as the total protobuf message were bellow the 4MiB limit. This is allowed to allocate lots of memory with very little entries.
This can be configured using theMaxCidSize
option and defaults to168 bytes
. - The server now closes the connection if an inline CID is requested (either as
WANT_*
orCANCEL
).
The attack were more effective if done with CIDs that are present in target's blockstore, this is because this will push longer-lasting jobs on some priority queue.
Since inline CID are literal data (instead of hashes of data), everyone always "has" any inline CID (since instead of loading the data from disk, it can be extracted from the CID). It makes no sense for anyone to ever ask you about an inline CID since they could also just parse it themselves. Thus, as a defensive measure, we kill the connection with peers that ask about an inline CID.
Vulnerable symbols
github.com/ipfs/go-libipfs/bitswap/server/internal/decision.(*Engine).MessageReceived
github.com/ipfs/go-libipfs/bitswap/server/internal/decision.(*Engine).NotifyNewBlocks
github.com/ipfs/go-libipfs/bitswap/server/internal/decision.(*Engine).findOrCreate
github.com/ipfs/go-libipfs/bitswap/server/internal/decision.(*Engine).PeerConnected
Patches
- https://github.com/ipfs/boxo/commit/9cb5cb54d40b57084d1221ba83b9e6bb3fcc3197 (mitigations 1 and 2)
- https://github.com/ipfs/boxo/commit/62cbac40b96f49e39cd7fedc77ee6b56adce4916 (mitigations 3 and 4)
- https://github.com/ipfs/boxo/commit/baa748b682fabb21a4c1f7628a8af348d4645974 (tests)
Workarounds
If you are using the stubs at github.com/ipfs/go-libipfs/bitswap
and not taking advantage of the features provided by the server, refactoring your code to use the new split API will allow you to run in a client-only mode using: github.com/ipfs/boxo/bitswap/client
.
JSON: https://advisories.ecosyste.ms/api/v1/advisories/GSA_kwCzR0hTQS1tOTc0LXhqNGotN3F2Nc4AAzSd
Source: GitHub Advisory Database
Origin: Unspecified
Severity: High
Classification: General
Published: 12 months ago
Updated: 6 months ago
CVSS Score: 8.2
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
Identifiers: GHSA-m974-xj4j-7qv5, CVE-2023-25568
References:
- https://github.com/ipfs/boxo/security/advisories/GHSA-m974-xj4j-7qv5
- https://github.com/ipfs/go-libipfs/security/advisories/GHSA-m974-xj4j-7qv5
- https://nvd.nist.gov/vuln/detail/CVE-2023-25568
- https://github.com/ipfs/boxo/commit/62cbac40b96f49e39cd7fedc77ee6b56adce4916
- https://github.com/ipfs/boxo/commit/9cb5cb54d40b57084d1221ba83b9e6bb3fcc3197
- https://github.com/ipfs/boxo/commit/baa748b682fabb21a4c1f7628a8af348d4645974
- https://github.com/advisories/GHSA-m974-xj4j-7qv5
Blast Radius: 7.8
Affected Packages
go:github.com/ipfs/go-libipfs
Dependent packages: 23Dependent repositories: 9
Downloads:
Affected Version Ranges: < 0.4.1, >= 0.5.0, < 0.6.0
Fixed in: 0.4.1, 0.6.0
All affected versions: 0.1.0, 0.2.0, 0.3.0, 0.4.0, 0.5.0
All unaffected versions: 0.4.1, 0.6.0, 0.6.1, 0.6.2