| name | p2p-dos-and-eclipse |
| description | L1 trigger - audits peer-to-peer networking for DoS vectors (resource exhaustion, amplification), eclipse attack susceptibility, and discovery table poisoning (Kademlia/devp2p). |
Injectable Skill: P2P DoS and Eclipse Attacks
L1 trigger: L1_PATTERN=true AND (p2p/ OR network/ OR discovery/ OR libp2p OR devp2p OR enr OR discv5 detected in recon subsystem map)
Inject Into: depth-network-surface
Language: Go and Rust
Finding prefix: [P2P-N]
Status: v0.1 draft, Round 4 exemplars pending
Orchestrator Decomposition Guide
- Sections 1, 2: depth-network-surface (attack surface + DoS)
- Section 3: depth-state-trace (peer table state)
- Section 4: depth-edge-case (boundary/adversarial peer states)
When This Skill Activates
Recon identifies a P2P subsystem. Most attacks in this class are out-of-scope for typical bounty programs but are in scope for Plamen audits — firms like Sigma Prime and OpenZeppelin explicitly cover them. Severity downgrades to Low/Info when the exploit only eclipses a single node (see severity-matrix.md); upgrades when reachable by arbitrary peers and amplifies across the network.
1. Attack Surface Enumeration (Entry Points)
Every P2P subsystem has a finite set of entry points for remote adversary bytes. Enumerate them using LSP workspace/symbol and ast-grep:
| Entry point type | How to find | Example functions |
|---|
| Message handlers | Trait/interface impl names ending in Handler, Service, Listener | handleGetBlockHeaders, on_new_pooled_transaction_hashes |
| Decoders | Functions taking &[u8] or Reader and returning protocol types | decode_enr, rlp_decode |
| Connection accepters | TCP/QUIC listener accept loops | acceptLoop, handle_connection |
| Discovery responders | UDP packet handlers for discovery protocol | handleDiscv5Packet, process_find_node |
| Gossip handlers | Pubsub topic subscribers | process_gossip_message |
Write the enumeration into scratchpad/p2p_surface.md before proceeding.
2. DoS Classes to Check per Entry Point
2a. Asymmetric processing cost
Attacker sends N bytes, node does O(N²) or O(N*log(N)) work. Classic example: decompression bombs, hash-map insertion of attacker-chosen keys (hash DoS), large RLP lists.
Check:
- For each decoder, is there a max size limit before parsing begins?
- For each list/vector field, is there a max element count enforced?
- For each recursive decoder, is there a max recursion depth?
- For each hash-map insert of attacker-controlled data, is the map key pre-hashed or is a SipHash-random-keyed map used?
Tag: [P2P-ASYMMETRIC:{loc}:{input-size}→{work-cost}]
2b. Unbounded memory growth
Handlers that buffer or queue indefinitely.
Check:
- Every channel/queue: does it have a bounded capacity? What happens on overflow — block, drop, or OOM?
- Every
append / Vec::push in a loop that can be driven by adversary: is there a bound?
- Every peer-keyed map (peer → state): is there an eviction policy when size > threshold?
Tag: [P2P-UNBOUNDED:{structure}:{growth-driver}]
2c. Unbounded CPU: infinite loops or pathological inputs
Handlers that can loop forever or spend minutes on malicious input.
Check:
- Every
for loop in a handler: what bounds termination? Attacker-controlled?
- Regex with catastrophic backtracking (if any regex is used on peer input)
- Crypto operations on unvalidated length inputs
Tag: [P2P-CPU:{loc}:{termination-condition}]
2d. Connection slot exhaustion
Attacker opens N connections with M peers, filling the connection table.
Check:
- What is the max inbound connection limit? (Geth: 50, Bitcoin: 125)
- Is there a per-IP limit? Per-/24-subnet limit? Per-ASN limit?
- How long can a half-open (TCP SYN + no handshake) connection hold a slot?
- Does the node prioritize connections from diverse IP ranges?
- Outbound bootstrap handshake cap: when a joining node receives a peer list from a bootnode, does it cap the number of addresses it attempts to handshake in parallel? Without a cap, a malicious bootnode (or a peer-list response with N>>peer-table-size) forces the joiner to exhaust file descriptors / memory / connection slots during startup. Verify both the per-bootstrap response cap AND the in-flight handshake concurrency limit.
Tag: [P2P-SLOTS:{limit}:{diversification}], [P2P-BOOTSTRAP-FLOOD:{cap-or-unbounded}]
2e. Amplification
Attacker sends small message, node sends large response — used to DDoS third parties.
Check:
- For every request-response pair, compare input size vs output size
- Discovery protocols (UDP) are especially dangerous — no handshake, easy spoofing
- Is source-address validation (rate-limited ENR responses, etc.) in place?
Tag: [P2P-AMPLIFY:{request-bytes}→{response-bytes}]
2g. Re-gossip dedup discipline (echo-chamber amplification)
For each gossip handler that RECEIVES data and then FORWARDS it to other peers (re-gossip), trace the dedup path. This is a separate concern from 2a (single-message cost) — it covers network-multiplication attacks.
Check:
- Is there a "recent-seen" or "recent-valid" cache that BLOCKS re-broadcast on duplicates?
- Is the cache check BEFORE the broadcast spawn /
.send() call, not after?
- Is the cache key the message hash (not the message contents, which an attacker can mutate while preserving semantics)?
- Is the cache populated AFTER signature/validity verification, not before? Recording-as-seen pre-verification creates a "seen-cache poisoning" primitive: an attacker injects an invalid item with a valid ID, the cache records it, the legitimate version from honest peers is then dropped as "already seen".
- For each handler, walk the order of operations:
verify_signature → record_seen → broadcast. Any other order is a finding.
Fail mode: an N-peer network re-gossips each message O(N²) times, saturating bandwidth in an "echo chamber" pattern. NEAR / Tendermint / Geth have all had variants of this bug. Combined with seen-cache poisoning, an attacker can both flood the network AND censor legitimate items.
Tag: [P2P-AMPLIFY:re-gossip-dedup:{file}:{line}] and [P2P-CACHE-POISON:record-before-verify:{file}:{line}]
2h. Sequential broadcast vs parallel broadcast
Many P2P implementations naively use for peer in active_peers { client.send(peer, msg).await; } to broadcast. Each peer's response time blocks the next. A single slow peer (intentional or not) delays the entire broadcast cycle.
Check:
- For each broadcast loop, identify whether peers are processed sequentially with
.await or in parallel with tokio::join_all / FuturesUnordered / select!.
- For sequential broadcast loops, calculate worst-case wall-clock:
peer_count × per-peer-timeout. If this exceeds block time, propagation is broken under adversarial peer growth.
- Cap the total broadcast peer count to a constant (e.g., 200 randomly sampled peers); rely on gossip amplification for full propagation.
Tag: [P2P-CPU:sequential-broadcast:{loc}]
3. Eclipse Attack Vectors
An eclipse attack isolates a target node by monopolizing its peer table entries.
3a. Peer table structure
- Identify the peer table data structure (Kademlia k-buckets, flat table, discovery v5 ENR table)
- For each bucket, what is the k value and eviction policy?
- Is peer selection stratified by IP/ASN diversity, or purely by XOR distance?
3b. Peer ID generation cost
- How expensive is it to produce a peer ID that lands in a target bucket?
- Ethereum discovery v5: node ID = hash(public key). Generating thousands of node IDs is cheap.
- Some protocols require proof-of-work for peer IDs; most don't.
- Is there a rate limit on accepting new peer announcements?
3c. Bootstrap / rejoin vulnerability
On restart, the node uses a static bootstrap list, then populates its peer table from responses. If an attacker can intercept or outrun the bootstrap response, they control the initial peer set.
Check: What bootnodes are used? Are they hardcoded or configurable? What happens if all bootnodes are unreachable?
3d. ENR/record poisoning
Discovery v5 uses signed ENRs. Can an attacker poison a victim's ENR cache with malicious entries?
Check: ENR signature verification on every incoming record. ENR seqnum monotonic update.
Tag: [ECLIPSE:{vector}:{countermeasure-state}]
Known exemplar class: devp2p issue #109 (Ethereum discv5 eclipse concerns); academic low-resource eclipse attacks on older Geth.
4. Peer Scoring and Banning
Most clients have a peer scoring system: peers that misbehave (send invalid data, stall, equivocate) accumulate negative score and get banned.
Patterns to flag
- Integer overflow in score: if score is
i32, repeatedly adding -MAX causes wrap. Geth has historically had integer-overflow issues in peer scoring.
- Permanent ban on transient fault: banning on a single protocol error can be exploited to deny service to honest peers via spoofed errors
- Asymmetric scoring: does good behavior recover lost score? If not, a single bad day permanently bans a good peer
- Scoring based on attacker-controlled timing: if score updates on every packet and attacker can drive packet rate, scoring becomes attacker-controlled
Tag: [P2P-SCORE:{vulnerability-class}]
5. Gossip / Pubsub
If the protocol uses gossipsub or similar pubsub:
- Message deduplication: is there a seen-cache? How large? What TTL? Can it be exhausted?
- Topic validation: are topic names validated before subscribing? Can an attacker force the node to subscribe to an expensive topic?
- Mesh sizing: mesh degree (D, D_low, D_high) — are these enforced? Can an attacker manipulate mesh composition?
- Message size: max message size in the pubsub layer vs the application layer — mismatch is a DoS vector
Tag: [GOSSIP:{param}:{value-or-unbounded}]
6. Output schema
- Layer: network
- Bug class: asymmetric-cost / unbounded-resource / slot-exhaustion / amplification / eclipse / peer-score / gossip
- Preferred evidence tags:
[FUZZ-PASS] (D2PFuzz or libfuzzer on decoder) > [LSP-TRACE] > [CODE-TRACE]
- Severity baseline: Medium by default; upgrade to High if network-wide amplification; downgrade to Low/Info if single-node eclipse only
7. Known bug exemplars (v0.2 — Round 4 verified)
-
NEAR Signature::verify pre-auth handshake panic (December 2023) — $150,000 bounty. In SECP256K1 branch of Signature::verify(), Message::from_slice(data).expect("32 bytes") panics when payload > 32 bytes; RecoveryId::from_i32().unwrap() panics on recovery byte > 3. A single crafted Tier1Handshake/Tier2Handshake message kills any node. Pre-auth = any peer can do it. Fixed PR #10385 (commit e0f0da5c3dde29122e956dfd905811890de9a570). Zellic Web3 Ping of Death. Skill catch point: pre-auth panic check — for every handshake / pre-auth message handler, trace every .unwrap(), .expect(), panic!(), slice index, conversion. Assert graceful error return for all input classes.
-
Marcus-Heilman low-resource Ethereum eclipse (2018) — Geth's Kademlia discovery table could be monopolized by an attacker with only 2 IPs. Fixed in geth 1.8 (Feb 2018). Low-Resource Eclipse Attacks on Ethereum. Skill catch point: Section 3a — bucket eviction policy, IP/ASN stratification, rate-limit on new peer announcements.
-
D2PFuzz differential p2p bugs across 5 clients (IEEE 2025) — network-layer differential fuzzer found 15 unique bugs, 12 previously unknown by mutating DevP2P messages and diffing responses across geth, erigon, reth, besu, nethermind. Network-Layer Differential Fuzzing for Ethereum. Skill catch point: Section 1 — enumerate every DevP2P message type; verify response semantics against spec for valid / malformed / boundary / timing inputs; compare against ≥2 other client responses.
-
Henningsen "false friends" Ethereum eclipse (2019) — follow-up to Marcus-Heilman. Geth's peer-eviction policy could be gamed with valid-looking false-friend nodes. Eclipsing Ethereum Peers with False Friends. Skill catch point: Section 4 — audit peer scoring for monotonicity; new peers from unknown sources must not displace established trusted peers.
-
Geth CVE-2025-24883 RLPx handshake crash — all-zero secp256k1 public key accepted without subgroup validation. Single malicious peer crashes any node. GHSA-q26p-9cq4-7fc2. : cryptographic handshake inputs must be validated as on-curve AND in-subgroup BEFORE any math operation. (Shared with Section 2.)
Critical methodology addition from Round 4 (pre-auth panic = single-packet node kill)
Insert as new Section 2f (highest priority): Pre-auth message handlers are the hottest P2P surface. Every panic in a pre-auth path is a single-packet node-kill primitive. Methodology:
- List every message handler reachable before authentication/handshake completion
- For each, ast-grep or manual-read:
.unwrap(), .expect(, panic!(, slice indexing [i], type assertion .(T) without ok, unreachable!(), integer division
- Every one of these is a finding until proven bounded (e.g., a length check earlier in the call chain)
Tag: [P2P-PANIC-PREAUTH:{handler}:{panic-site}]
2i. Peer Scoring Symmetry Audit
Peer scoring only works if rewards AND penalties are both applied. A one-sided system lets malicious peers farm reputation without consequence. This section forces enumeration.
Required artifact: write {SCRATCHPAD}/peer_scoring_symmetry.md:
# Peer Scoring Symmetry: {protocol_name}
| Event | Reward path | Penalty path | Symmetric? |
|---|---|---|---|
| Successful block delivery | score.rs:L42 +1 | — | **ASYMMETRIC** |
| Invalid block response | — | score.rs:L78 -5 | OK |
| Health check failure | — | — | **MISSING** |
| /get_data served | +1 | — | **FARMABLE** |
Methodology:
- Find the peer scoring module (
peer_score, reputation, scoring).
- Enumerate EVERY event type the scoring system knows about — extract from the enum/struct mapping events to score deltas, not from memory.
- For each event, find BOTH reward and penalty paths. Missing either → ASYMMETRIC finding.
check_health specifically: does it decrement on HTTP errors / timeouts, or only on explicit Ok(false)? A no-op on failure is a finding.- Verify failure-class coverage: "only InvalidData triggers penalty" while "BlockPool" or other validation failures are silent → finding.
- Data request endpoints (
/get_data, request_blocks): if the success path increments score with no rate limit or deduplication → FARMABLE finding.
- Asymmetric scoring is always at least Medium severity.
Tag: [PEER-SCORE-ASYMMETRIC:{event}], [PEER-SCORE-FARMABLE:{event}], [PEER-SCORE-NO-PENALTY:{failure_class}]
8. Fallback if primitives unavailable
- List files under
p2p/ and discovery/
- Grep for
handleRLP, decode_rlp, handle_message function definitions
- Check for explicit size limits: grep
MaxSize, MAX_, limit
- Read the bootstrap node list
Cross-references
- Related:
mempool-asymmetric-dos, consensus-safety-invariants (equivocation detection interacts with peer scoring)
- Consumed by:
depth-network-surface
- Severity:
docs/l1-mode/severity-matrix.md
