October 2023 - cypherpunks - lists.cpunks.org

Re: [spam][crazy][fiction][random] Non-Canon MCBoss Spinoffs
by Undescribed Horrific Abuse, One Victim & Survivor of Many 21 Oct '23

21 Oct '23

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Collapse of govts
by professor rat 21 Oct '23

21 Oct '23

The bigger they come the harder they'll fall https://cointelegraph.com/news/artificial-general-intelligence-singularityn… Reposts not yet more core c-punk predictions materializing right before our thunderstruck eyes

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[ot] Center for Jewish Nonviolence: Israel/Palestine
by professor rat 21 Oct '23

21 Oct '23

Listen to this High Priest of indescribable mysteries preaching! Jesus Fucking Christ, agent Semich. You suck. Go die. One thing is clear now – world peace will not come until the AGENT SEMICH list occupation ends and PUNKS are free. True safety is only possible when we act in solidarity with one another. Now more than ever, it is our responsibility as anarchist activists from around the world to continue resisting, shoulder to shoulder with our Palestinian and Israeli partners, for a just future where everyone lives with freedom and dignity.

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Crypto Mixers as National Security Threats, Fuck Yeah!
by professor rat 21 Oct '23

21 Oct '23

USG agent Semich >>> mixer not deanonymized <<< Deanonymize yourself or STFU agent Semich >>> horrible things happening to palestinians <<< If this means " Undescribed Horrific Abuse " it means zero.

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Israeli anarchism - bourn into this
by professor rat 21 Oct '23

21 Oct '23

" . . . I’m an anarchist from Haifa, Occupied Palestine. Been active for more than a decade, mainly in the anti-colonial movement and solidarity with Palestinians, animal liberation and ecological issues. How did you become an anarchist? The short answer is punk. The longer answer is of course a bit more difficult. Growing up as a settler under a colonial apartheid regime, on the „right” side of the fence, being assigned Jewish by the state, naturally you’re expected not to rebel and become a prison guard like the rest. You’re growing up surrounded with militarist imagery, Zionist indoctrination in school, and historical events like the holocaust and the Jewish religion are weaponized to boost patriotism and nationalist propaganda. The version of Judaism being taught here is that we are the chosen people, this land belongs to us by divine decree, God is a real estate agent that can be used in any land dispute, and everyone else is destined to be second class citizens at best. . . . " FROM https://161crew.bzzz.net/interview-with-an-israeli-anarchist/ Reposts not garbage from Gramps maggot-infested, scow-house

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Anarchist Lev Skoryakin kidnapped in Kyrgyzstan
by professor rat 21 Oct '23

21 Oct '23

https://avtonom.org/en/news/anarchist-lev-skoryakin-kidnapped-kyrgyzstan Reposts not deputy-dog, dribble from US policing agent, Karl Semich

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Freedom has a price
by zeynep＠keemail.me 20 Oct '23

20 Oct '23

https://en.m.wikipedia.org/wiki/Carlo_Caracciolo

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Re: [bitcoin-dev] [Lightning-dev] Full Disclosure: CVE-2023-40231 / CVE-2023-40232 / CVE-2023-40233 / CVE-2023-40234 "All your mempool are belong to us"
by Undescribed Horrific Abuse, One Victim & Survivor of Many 20 Oct '23

20 Oct '23

On 10/17/23, Matt Corallo via bitcoin-dev <bitcoin-dev(a)lists.linuxfoundation.org> wrote: > There appears to be some confusion about this issue and the mitigations. To > be clear, the deployed > mitigations are not expected to fix this issue, its arguable if they provide > anything more than a PR > statement. > > There are two discussed mitigations here - mempool scanning and transaction > re-signing/re-broadcasting. > > Mempool scanning relies on regularly checking the mempool of a local node to > see if we can catch the > replacement cycle mid-cycle. It only works if wee see the first transaction > before the second > transaction replaces it. > > Today, a large majority of lightning nodes run on machines with a Bitcoin > node on the same IP > address, making it very clear what the "local node" of the lightning node > is. An attacker can > trivially use this information to connect to said local node and do the > replacement quickly, > preventing the victim from seeing the replacement. > > More generally, however, similar discoverability is true for mining pools. > An attacker performing > this attack is likely to do the replacement attack on a miner's node > directly, potentially reducing > the reach of the intermediate transaction to only miners, such that the > victim can never discover it > at all. > > The second mitigation is similarly pathetic. Re-signing and re-broadcasting > the victim's transaction > in an attempt to get it to miners even if its been removed may work, if the > attacker is super lazy > and didn't finish writing their attack system. If the attacker is connected > to a large majority of > hashrate (which has historically been fairly doable), they can simply do > their replacement in a > cycle aggressively and arbitrarily reduce the probability that the victim's > transaction gets confirmed. > > Now, the above is all true in a spherical cow kinda world, and the P2P > network has plenty of slow > nodes and strange behavior. Its possible that these mitigations might, by > some stroke of luck, > happen to catch such an attack and prevent it, because something took longer > than the attacker > intended or whatever. But, that's a far cry from any kind of material "fix" > for the issue. > > Ultimately the only fix for this issue will be when miners keep a history of > transactions they've > seen and try them again after they may be able to enter the mempool because > of an attack like this. > > Matt > > On 10/16/23 12:57 PM, Antoine Riard wrote: >> (cross-posting mempool issues identified are exposing lightning chan to >> loss of funds risks, other >> multi-party bitcoin apps might be affected) >> >> Hi, >> >> End of last year (December 2022), amid technical discussions on eltoo >> payment channels and >> incentives compatibility of the mempool anti-DoS rules, a new >> transaction-relay jamming attack >> affecting lightning channels was discovered. >> >> After careful analysis, it turns out this attack is practical and >> immediately exposed lightning >> routing hops carrying HTLC traffic to loss of funds security risks, both >> legacy and anchor output >> channels. A potential exploitation plausibly happening even without >> network mempools congestion. >> >> Mitigations have been designed, implemented and deployed by all major >> lightning implementations >> during the last months. >> >> Please find attached the release numbers, where the mitigations should be >> present: >> - LDK: v0.0.118 - CVE-2023 -40231 >> - Eclair: v0.9.0 - CVE-2023-40232 >> - LND: v.0.17.0-beta - CVE-2023-40233 >> - Core-Lightning: v.23.08.01 - CVE-2023-40234 >> >> While neither replacement cycling attacks have been observed or reported >> in the wild since the last >> ~10 months or experimented in real-world conditions on bitcoin mainet, >> functional test is available >> exercising the affected lightning channel against bitcoin core mempool >> (26.0 release cycle). >> >> It is understood that a simple replacement cycling attack does not demand >> privileged capabilities >> from an attacker (e.g no low-hashrate power) and only access to basic >> bitcoin and lightning >> software. Yet I still think executing such an attack successfully requests >> a fair amount of bitcoin >> technical know-how and decent preparation. >> >> From my understanding of those issues, it is yet to be determined if the >> mitigations deployed are >> robust enough in face of advanced replacement cycling attackers, >> especially ones able to combine >> different classes of transaction-relay jamming such as pinnings or vetted >> with more privileged >> capabilities. >> >> Please find a list of potential affected bitcoin applications in this full >> disclosure report using >> bitcoin script timelocks or multi-party transactions, albeit no immediate >> security risk exposure as >> severe as the ones affecting lightning has been identified. Only cursory >> review of non-lightning >> applications has been conducted so far. >> >> There is a paper published summarizing replacement cycling attacks on the >> lightning network: >> https://github.com/ariard/mempool-research/blob/2023-10-replacement-paper/r… >> >> <https://github.com/ariard/mempool-research/blob/2023-10-replacement-paper/r…> >> >> ## Problem >> >> A lightning node allows HTLCs forwarding (in bolt3's parlance accepted >> HTLC on incoming link and >> offered HTLC on outgoing link) should settle the outgoing state with >> either a success or timeout >> before the incoming state timelock becomes final and an asymmetric >> defavorable settlement might >> happen (cf "Flood & Loot: A Systematic Attack on The Lightning Network" >> section 2.3 for a classical >> exposition of this lightning security property). >> >> Failure to satisfy this settlement requirement exposes a forwarding hop to >> a loss of fund risk where >> the offered HTLC is spent by the outgoing link counterparty's >> HTLC-preimage and the accepted HTLC is >> spent by the incoming link counterparty's HTLC-timeout. >> >> The specification mandates the incoming HTLC expiration timelock to be >> spaced out by an interval of >> `cltv_expiry_delta` from the outgoing HTLC expiration timelock, this exact >> interval value being an >> implementation and node policy setting. As a minimal value, the >> specification recommends 34 blocks >> of interval. If the timelock expiration I of the inbound HTLC is equal to >> 100 from chain tip, the >> timelock expiration O of the outbound HTLC must be equal to 66 blocks from >> chain tip, giving a >> reasonable buffer of reaction to the lightning forwarding node. >> >> In the lack of cooperative off-chain settlement of the HTLC on the >> outgoing link negotiated with the >> counterparty (either `update_fulfill_htlc` or `update_fail_htlc`) when O >> is reached, the lightning >> node should broadcast its commitment transaction. Once the commitment is >> confirmed (if anchor and >> the 1 CSV encumbrance is present), the lightning node broadcasts and >> confirms its HTLC-timeout >> before I height is reached. >> >> Here enter a replacement cycling attack. A malicious channel counterparty >> can broadcast its >> HTLC-preimage transaction with a higher absolute fee and higher feerate >> than the honest HTLC-timeout >> of the victim lightning node and triggers a replacement. Both for legacy >> and anchor output channels, >> a HTLC-preimage on a counterparty commitment transaction is malleable, i.e >> additional inputs or >> outputs can be added. The HTLC-preimage spends an unconfirmed and >> unrelated to the channel parent >> transaction M and conflicts its child. >> >> As the HTLC-preimage spends an unconfirmed input that was already included >> in the unconfirmed and >> unrelated child transaction (rule 2), pays an absolute higher fee of at >> least the sum paid by the >> HTLC-timeout and child transaction (rule 3) and the HTLC-preimage feerate >> is greater than all >> directly conflicting transactions (rule 6), the replacement is accepted. >> The honest HTLC-timeout is >> evicted out of the mempool. >> >> In an ulterior move, the malicious counterparty can replace the parent >> transaction itself with >> another candidate N satisfying the replacement rules, triggering the >> eviction of the malicious >> HTLC-preimage from the mempool as it was a child of the parent T. >> >> There is no spending candidate of the offered HTLC output for the current >> block laying in network >> mempools. >> >> This replacement cycling tricks can be repeated for each rebroadcast >> attempt of the HTLC-timeout by >> the honest lightning node until expiration of the inbound HTLC timelock I. >> Once this height is >> reached a HTLC-timeout is broadcast by the counterparty's on the incoming >> link in collusion with the >> one on the outgoing link broadcasting its own HTLC-preimage. >> >> The honest Lightning node has been "double-spent" in its HTLC forwarding. >> >> As a notable factor impacting the success of the attack, a lightning >> node's honest HTLC-timeout >> might be included in the block template of the miner winning the block >> race and therefore realizes a >> spent of the offered output. In practice, a replacement cycling attack >> might over-connect to miners' >> mempools and public reachable nodes to succeed in a fast eviction of the >> HTLC-timeout by its >> HTLC-preimage. As this latter transaction can come with a better >> ancestor-score, it should be picked >> up on the flight by economically competitive miners. >> >> A functional test exercising a simple replacement cycling of a HTLC >> transaction on bitcoin core >> mempool is available: >> https://github.com/ariard/bitcoin/commits/2023-test-mempool >> <https://github.com/ariard/bitcoin/commits/2023-test-mempool> >> >> ## Deployed LN mitigations >> >> Aggressive rebroadcasting: As the replacement cycling attacker benefits >> from the HTLC-timeout being >> usually broadcast by lightning nodes only once every block, or less the >> replacement cycling >> malicious transactions paid only equal the sum of the absolute fees paid >> by the HTLC, adjusted with >> the replacement penalty. Rebroadcasting randomly and multiple times before >> the next block increases >> the absolute fee cost for the attacker. >> >> Implemented and deployed by Eclair, Core-Lightning, LND and LDK . >> >> Local-mempool preimage monitoring: As the replacement cycling attacker in >> a simple setup broadcast >> the HTLC-preimage to all the network mempools, the honest lightning node >> is able to catch on the >> flight the unconfirmed HTLC-preimage, before its subsequent mempool >> replacement. The preimage can be >> extracted from the second-stage HTLC-preimage and used to fetch the >> off-chain inbound HTLC with a >> cooperative message or go on-chain with it to claim the accepted HTLC >> output. >> >> Implemented and deployed by Eclair and LND. >> >> CLTV Expiry Delta: With every jammed block comes an absolute fee cost paid >> by the attacker, a risk >> of the HTLC-preimage being detected or discovered by the honest lightning >> node, or the HTLC-timeout >> to slip in a winning block template. Bumping the default CLTV delta >> hardens the odds of success of a >> simple replacement cycling attack. >> >> Default setting: Eclair 144, Core-Lightning 34, LND 80 and LDK 72. >> >> ## Affected Bitcoin Protocols and Applications >> >> From my understanding the following list of Bitcoin protocols and >> applications could be affected by >> new denial-of-service vectors under some level of network mempools >> congestion. Neither tests or >> advanced review of specifications (when available) has been conducted for >> each of them: >> - on-chain DLCs >> - coinjoins >> - payjoins >> - wallets with time-sensitive paths >> - peerswap and submarine swaps >> - batch payouts >> - transaction "accelerators" >> >> Inviting their developers, maintainers and operators to investigate how >> replacement cycling attacks >> might disrupt their in-mempool chain of transactions, or fee-bumping flows >> at the shortest delay. >> Simple flows and non-multi-party transactions should not be affected to >> the best of my understanding. >> >> ## Open Problems: Package Malleability >> >> Pinning attacks have been known for years as a practical vector to >> compromise lightning channels >> funds safety, under different scenarios (cf. current bip331's motivation >> section). Mitigations at >> the mempool level have been designed, discussed and are under >> implementation by the community >> (ancestor package relay + nverrsion=3 policy). Ideally, they should >> constraint a pinning attacker to >> always attach a high feerate package (commitment + CPFP) to replace the >> honest package, or allow a >> honest lightning node to overbid a malicious pinning package and get its >> time-sensitive transaction >> optimistically included in the chain. >> >> Replacement cycling attack seem to offer a new way to neutralize the >> design goals of package relay >> and its companion nversion=3 policy, where an attacker package RBF a >> honest package out of the >> mempool to subsequently double-spend its own high-fee child with a >> transaction unrelated to the >> channel. As the remaining commitment transaction is pre-signed with a >> minimal relay fee, it can be >> evicted out of the mempool. >> >> A functional test exercising a simple replacement cycling of a lightning >> channel commitment >> transaction on top of the nversion=3 code branch is available: >> https://github.com/ariard/bitcoin/commits/2023-10-test-mempool-2 >> <https://github.com/ariard/bitcoin/commits/2023-10-test-mempool-2> >> >> ## Discovery >> >> In 2018, the issue of static fees for pre-signed lightning transactions is >> made more widely known, >> the carve-out exemption in mempool rules to mitigate in-mempool package >> limits pinning and the >> anchor output pattern are proposed. >> >> In 2019, bitcoin core 0.19 is released with carve-out support. Continued >> discussion of the anchor >> output pattern as a dynamic fee-bumping method. >> >> In 2020, draft of anchor output submitted to the bolts. Initial finding of >> economic pinning against >> lightning commitment and second-stage HTLC transactions. Subsequent >> discussions of a >> preimage-overlay network or package-relay as mitigations. Public call made >> to inquiry more on >> potential other transaction-relay jamming attacks affecting lightning. >> >> In 2021, initial work in bitcoin core 22.0 of package acceptance. >> Continued discussion of the >> pinning attacks and shortcomings of current mempool rules during >> community-wide online workshops. >> Later the year, in light of all issues for bitcoin second-layers, a >> proposal is made about killing >> the mempool. >> >> In 2022, bip proposed for package relay and new proposed v3 policy design >> proposed for a review and >> implementation. Mempoolfullrbf is supported in bitcoin core 24.0 and >> conceptual questions about >> alignment of mempool rules w.r.t miners incentives are investigated. >> >> Along this year 2022, eltoo lightning channels design are discussed, >> implemented and reviewed. In >> this context and after discussions on mempool anti-DoS rules, I discovered >> this new replacement >> cycling attack was affecting deployed lightning channels and immediately >> reported the finding to >> some bitcoin core developers and lightning maintainers. >> >> ## Timeline >> >> - 2022-12-16: Report of the finding to Suhas Daftuar, Anthony Towns, Greg >> Sanders and Gloria Zhao >> - 2022-12-16: Report to LN maintainers: Rusty Russell, Bastien Teinturier, >> Matt Corallo and Olaoluwa >> Osuntunkun >> - 2022-12-23: Sharing to Eugene Siegel (LND) >> - 2022-12-24: Sharing to James O'Beirne and Antoine Poinsot (non-lightning >> potential affected projects) >> - 2022-01-14: Sharing to Gleb Naumenko (miners incentives and cross-layers >> issuers) and initial >> proposal of an early public disclosure >> - 2022-01-19: Collection of analysis if other second-layers and >> multi-party applications affected. >> LN mitigations development starts. >> - 2023-05-04: Sharing to Wilmer Paulino (LDK) >> - 2023-06-20: LN mitigations implemented and progressively released. Week >> of the 16 october proposed >> for full disclosure. >> - 2023-08-10: CVEs assigned by MITRE >> - 2023-10-05: Pre-disclosure of LN CVEs numbers and replacement cycling >> attack existence to >> security(a)bitcoincore.org <mailto:security@bitcoincore.org>. >> - 2023-10-16: Full disclosure of CVE-2023-40231 / CVE-2023-40232 / >> CVE-2023-40233 / CVE-2023-40234 >> and replacement cycling attacks >> >> ## Conclusion >> >> Despite the line of mitigations adopted and deployed by current major >> lightning implementations, I >> believe replacement cycling attacks are still practical for advanced >> attackers. Beyond this new >> attack might come as a way to partially or completely defeat some of the >> pinning mitigations which >> have been working for years as a community. >> >> As of today, it is uncertain to me if lightning is not affected by a more >> severe long-term package >> malleability critical security issue under current consensus rules, and if >> any other time-sensitive >> multi-party protocol, designed or deployed isn't de facto affected too >> (loss of funds or denial of >> service). >> >> Assuming analysis on package malleability is correct, it is unclear to me >> if it can be corrected by >> changes in replacement / eviction rules or mempool chain of transactions >> processing strategy. >> Inviting my technical peers and the bitcoin community to look more on this >> issue, including to >> dissent. I'll be the first one pleased if I'm fundamentally wrong on those >> issues, or if any element >> has not been weighted with the adequate technical accuracy it deserves. >> >> Do not trust, verify. All mistakes and opinions are my own. >> >> Antoine >> >> "meet with Triumph and Disaster. And treat those two impostors just the >> same" - K. >> >> _______________________________________________ >> Lightning-dev mailing list >> Lightning-dev(a)lists.linuxfoundation.org >> https://lists.linuxfoundation.org/mailman/listinfo/lightning-dev > _______________________________________________ > bitcoin-dev mailing list > bitcoin-dev(a)lists.linuxfoundation.org > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev >

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Re: [bitcoin-dev] [Lightning-dev] Full Disclosure: CVE-2023-40231 / CVE-2023-40232 / CVE-2023-40233 / CVE-2023-40234 "All your mempool are belong to us"
by Undescribed Horrific Abuse, One Victim & Survivor of Many 20 Oct '23

20 Oct '23

On 10/17/23, Antoine Riard via bitcoin-dev <bitcoin-dev(a)lists.linuxfoundation.org> wrote: > Hi Zeeman, > >> At block height 100, `B` notices the `B->C` HTLC timelock is expired > without `C` having claimed it, so `B` forces the `B====C` channel onchain. >> However, onchain feerates have risen and the commitment transaction and > HTLC-timeout transaction do not confirm. > > This is not that the HTLC-timeout does not confirm. It is replaced in > cycles by C's HTLC-preimage which is still valid after `B->C` HTLC timelock > has expired. And this HTLC-preimage is subsequently replaced itself. > > See the test here: > https://github.com/ariard/bitcoin/commit/19d61fa8cf22a5050b51c4005603f43d72… > >> At block height 144, `B` is still not able to claim the `A->B` HTLC, so > `A` drops the `A====B` channel onchain. >> As the fees are up-to-date, this confirms immediately and `A` is able to > recover the HTLC funds. >> However, the feerates of the `B====C` pre-signed transactions remain at > the old, uncompetitive feerates. > > This is correct that A tries to recover the HTLC funds on the `A===B` > channel. > > However, there is no need to consider the fee rates nor mempool congestion > as the exploit lays on the replacement mechanism itself (in simple > scenario). > >> At this point, `C` broadcasts an HTLC-success transaction with high > feerates that CPFPs the commitment tx. >> However, it replaces the HTLC-timeout transaction, which is at the old, > low feerate. >> `C` is thus able to get the value of the HTLC, but `B` is now no longer > able to use the knowledge of the preimage, as its own incoming HTLC was > already confirmed as claimed by `A`. > > This is correct that `C` broadcasts an HTLC-success transaction at block > height 144. > > However `C` broadcasts this high feerate transaction at _every block_ > between blocks 100 and 144 to replace B's HTLC-timeout transaction. > >> Let me also explain to non-Lightning experts why HTLC-timeout is > presigned in this case and why `B` cannot feebump it. > > Note `B` can feebump the HTLC-timeout for anchor output channels thanks to > sighash_single | anyonecanpay on C's signature. > > Le mar. 17 oct. 2023 à 11:34, ZmnSCPxj <ZmnSCPxj(a)protonmail.com> a écrit : > >> Good morning Antoine et al., >> >> Let me try to rephrase the core of the attack. >> >> There exists these nodes on the LN (letters `A`, `B`, and `C` are nodes, >> `==` are channels): >> >> A ===== B ===== C >> >> `A` routes `A->B->C`. >> >> The timelocks, for example, could be: >> >> A->B timeelock = 144 >> B->C timelock = 100 >> >> The above satisfies the LN BOLT requirements, as long as `B` has a >> `cltv_expiry_delta` of 44 or lower. >> >> After `B` forwards the HTLC `B->C`, C suddenly goes offline, and all the >> signed transactions --- commitment transaction and HTLC-timeout >> transactions --- are "stuck" at the feerate at the time. >> >> At block height 100, `B` notices the `B->C` HTLC timelock is expired >> without `C` having claimed it, so `B` forces the `B====C` channel >> onchain. >> However, onchain feerates have risen and the commitment transaction and >> HTLC-timeout transaction do not confirm. >> >> In the mean time, `A` is still online with `B` and updates the onchain >> fees of the `A====B` channel pre-signed transactions (commitment tx and >> HTLC-timeout tx) to the latest. >> >> At block height 144, `B` is still not able to claim the `A->B` HTLC, so >> `A` drops the `A====B` channel onchain. >> As the fees are up-to-date, this confirms immediately and `A` is able to >> recover the HTLC funds. >> However, the feerates of the `B====C` pre-signed transactions remain at >> the old, uncompetitive feerates. >> >> At this point, `C` broadcasts an HTLC-success transaction with high >> feerates that CPFPs the commitment tx. >> However, it replaces the HTLC-timeout transaction, which is at the old, >> low feerate. >> `C` is thus able to get the value of the HTLC, but `B` is now no longer >> able to use the knowledge of the preimage, as its own incoming HTLC was >> already confirmed as claimed by `A`. >> >> Is the above restatement accurate? >> >> ---- >> >> Let me also explain to non-Lightning experts why HTLC-timeout is >> presigned >> in this case and why `B` cannot feebump it. >> >> In the Poon-Dryja mechanism, the HTLCs are "infected" by the Poon-Dryja >> penalty case, and are not plain HTLCs. >> >> A plain HTLC offerred by `B` to `C` would look like this: >> >> (B && OP_CLTV) || (C && OP_HASH160) >> >> However, on the commitment transaction held by `B`, it would be infected >> by the penalty case in this way: >> >> (B && C && OP_CLTV) || (C && OP_HASH160) || (C && revocation) >> >> There are two changes: >> >> * The addition of a revocation branch `C && revocation`. >> * The branch claimable by `B` in the "plain" HTLC (`B && OP_CLTV`) also >> includes `C`. >> >> These are necessary in case `B` tries to cheat and this HTLC is on an >> old, >> revoked transaction. >> If the revoked transaction is *really* old, the `OP_CLTV` would already >> impose a timelock far in the past. >> This means that a plain `B && OP_CLTV` branch can be claimed by `B` if it >> retained this very old revoked transaction. >> >> To prevent that, `C` is added to the `B && OP_CLTV` branch. >> We also introduce an HTLC-timeout transaction, which spends the `B && C >> && >> OP_CLTV` branch, and outputs to: >> >> (B && OP_CSV) || (C && revocation) >> >> Thus, even if `B` held onto a very old revoked commitment transaction and >> attempts to spend the timelock branch (because the `OP_CLTV` is for an >> old >> blockheight), it still has to contend with a new output with a *relative* >> timelock. >> >> Unfortunately, this means that the HTLC-timeout transaction is >> pre-signed, >> and has a specific feerate. >> In order to change the feerate, both `B` and `C` have to agree to re-sign >> the HTLC-timeout transaction at the higher feerate. >> >> However, the HTLC-success transaction in this case spends the plain `(C >> && >> OP_HASH160)` branch, which only involves `C`. >> This allows `C` to feebump the HTLC-success transaction arbitrarily even >> if `B` does not cooperate. >> >> While anchor outputs can be added to the HTLC-timeout transaction as >> well, >> `C` has a greater advantage here due to being able to RBF the >> HTLC-timeout >> out of the way (1 transaction), while `B` has to get both HTLC-timeout >> and >> a CPFP-RBF of the anchor output of the HTLC-timeout transaction (2 >> transactions). >> `C` thus requires a smaller fee to achieve a particular feerate due to >> having to push a smaller number of bytes compared to `B`. >> >> Regards, >> ZmnSCPxj >> >

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Re: [bitcoin-dev] [Lightning-dev] Full Disclosure: CVE-2023-40231 / CVE-2023-40232 / CVE-2023-40233 / CVE-2023-40234 "All your mempool are belong to us"
by Undescribed Horrific Abuse, One Victim & Survivor of Many 20 Oct '23

20 Oct '23

On 10/17/23, ZmnSCPxj via bitcoin-dev <bitcoin-dev(a)lists.linuxfoundation.org> wrote: > Good morning Antoine et al., > > Let me try to rephrase the core of the attack. > > There exists these nodes on the LN (letters `A`, `B`, and `C` are nodes, > `==` are channels): > > A ===== B ===== C > > `A` routes `A->B->C`. > > The timelocks, for example, could be: > > A->B timeelock = 144 > B->C timelock = 100 > > The above satisfies the LN BOLT requirements, as long as `B` has a > `cltv_expiry_delta` of 44 or lower. > > After `B` forwards the HTLC `B->C`, C suddenly goes offline, and all the > signed transactions --- commitment transaction and HTLC-timeout transactions > --- are "stuck" at the feerate at the time. > > At block height 100, `B` notices the `B->C` HTLC timelock is expired without > `C` having claimed it, so `B` forces the `B====C` channel onchain. > However, onchain feerates have risen and the commitment transaction and > HTLC-timeout transaction do not confirm. > > In the mean time, `A` is still online with `B` and updates the onchain fees > of the `A====B` channel pre-signed transactions (commitment tx and > HTLC-timeout tx) to the latest. > > At block height 144, `B` is still not able to claim the `A->B` HTLC, so `A` > drops the `A====B` channel onchain. > As the fees are up-to-date, this confirms immediately and `A` is able to > recover the HTLC funds. > However, the feerates of the `B====C` pre-signed transactions remain at the > old, uncompetitive feerates. > > At this point, `C` broadcasts an HTLC-success transaction with high feerates > that CPFPs the commitment tx. > However, it replaces the HTLC-timeout transaction, which is at the old, low > feerate. > `C` is thus able to get the value of the HTLC, but `B` is now no longer able > to use the knowledge of the preimage, as its own incoming HTLC was already > confirmed as claimed by `A`. > > Is the above restatement accurate? > > ---- > > Let me also explain to non-Lightning experts why HTLC-timeout is presigned > in this case and why `B` cannot feebump it. > > In the Poon-Dryja mechanism, the HTLCs are "infected" by the Poon-Dryja > penalty case, and are not plain HTLCs. > > A plain HTLC offerred by `B` to `C` would look like this: > > (B && OP_CLTV) || (C && OP_HASH160) > > However, on the commitment transaction held by `B`, it would be infected by > the penalty case in this way: > > (B && C && OP_CLTV) || (C && OP_HASH160) || (C && revocation) > > There are two changes: > > * The addition of a revocation branch `C && revocation`. > * The branch claimable by `B` in the "plain" HTLC (`B && OP_CLTV`) also > includes `C`. > > These are necessary in case `B` tries to cheat and this HTLC is on an old, > revoked transaction. > If the revoked transaction is *really* old, the `OP_CLTV` would already > impose a timelock far in the past. > This means that a plain `B && OP_CLTV` branch can be claimed by `B` if it > retained this very old revoked transaction. > > To prevent that, `C` is added to the `B && OP_CLTV` branch. > We also introduce an HTLC-timeout transaction, which spends the `B && C && > OP_CLTV` branch, and outputs to: > > (B && OP_CSV) || (C && revocation) > > Thus, even if `B` held onto a very old revoked commitment transaction and > attempts to spend the timelock branch (because the `OP_CLTV` is for an old > blockheight), it still has to contend with a new output with a *relative* > timelock. > > Unfortunately, this means that the HTLC-timeout transaction is pre-signed, > and has a specific feerate. > In order to change the feerate, both `B` and `C` have to agree to re-sign > the HTLC-timeout transaction at the higher feerate. > > However, the HTLC-success transaction in this case spends the plain `(C && > OP_HASH160)` branch, which only involves `C`. > This allows `C` to feebump the HTLC-success transaction arbitrarily even if > `B` does not cooperate. > > While anchor outputs can be added to the HTLC-timeout transaction as well, > `C` has a greater advantage here due to being able to RBF the HTLC-timeout > out of the way (1 transaction), while `B` has to get both HTLC-timeout and a > CPFP-RBF of the anchor output of the HTLC-timeout transaction (2 > transactions). > `C` thus requires a smaller fee to achieve a particular feerate due to > having to push a smaller number of bytes compared to `B`. > > Regards, > ZmnSCPxj > _______________________________________________ > bitcoin-dev mailing list > bitcoin-dev(a)lists.linuxfoundation.org > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev >

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