CVE-2018-17144 Full Disclosure

CVE-2018-17144, a fix for which was released on September 18th in bitcoin Core versions 0.16.3 and 0.17.0rc4, includes both a Denial of Service component and a critical inflation vulnerability. It was originally reported to several developers working on bitcoin Core, as well as projects supporting other cryptocurrencies, including ABC and Unlimited on September 17th as a Denial of Service bug only, however we quickly determined that the issue was also an inflation vulnerability with the same root cause and fix.

In order to encourage rapid upgrades, the decision was made to immediately patch and disclose the less serious Denial of Service vulnerability, concurrently with reaching out to miners, businesses, and other affected systems while delaying publication of the full issue to give times for systems to upgrade. On September 20th a post in a public forum reported the full impact and although it was quickly retracted the claim was further circulated.

At this time we believe over half of the bitcoin hashrate has upgraded to patched nodes. We are unaware of any attempts to exploit this vulnerability.

However, it still remains critical that affected users upgrade and apply the latest patches to ensure no possibility of large reorganizations, mining of invalid blocks, or acceptance of invalid transactions occurs.

In bitcoin Core 0.14, an optimization was added (bitcoin Core PR #9049) which avoided a costly check during initial pre-relay block validation that multiple inputs within a single transaction did not spend the same input twice which was added in 2012 (PR #443). While the UTXO-updating logic has sufficient knowledge to check that such a condition is not violated in 0.14 it only did so in a sanity check assertion and not with full error handling (it did, however, fully handle this case twice in prior to 0.8).

Thus, in bitcoin Core 0.14.X, any attempts to double-spend a transaction output within a single transaction inside of a block will result in an assertion failure and a crash, as was originally reported.

In bitcoin Core 0.15, as a part of a larger redesign to simplify unspent transaction output tracking and correct a resource exhaustion attack the assertion was changed subtly. Instead of asserting that the output being marked spent was previously unspent, it only asserts that it exists.

Thus, in bitcoin Core 0.15.X, 0.16.0, 0.16.1, and 0.16.2, any attempts to double-spend a transaction output within a single transaction inside of a block where the output being spent was created in the same block, the same assertion failure will occur (as exists in the test case which was included in the 0.16.3 patch). However, if the output being double-spent was created in a previous block, an entry will still remain in the CCoin map with the DIRTY flag set and having been marked as spent, resulting in no such assertion. This could allow a miner to inflate the supply of bitcoin as they would be then able to claim the value being spent twice.

Timeline for September 17, 2018: (all times UTC)

14:57 anonymous reporter reports crash bug to: Pieter Wuille, Greg Maxwell, Wladimir Van Der Laan of bitcoin Core, deadalnix of bitcoin ABC, and sickpig of bitcoin Unlimited.
15:15 Greg Maxwell shares the original report with Cory Fields, Suhas Daftuar, Alex Morcos and Matt Corallo
17:47 Matt Corallo identifies inflation bug
19:15 Matt Corallo first tries to reach slushpool CEO to have a line of communication open to apply a patch quickly
19:29 Greg Maxwell timestamps the hash of a test-case which demonstrates the inflation vulnerability (a47344b7dceddff6c6cc1c7e97f1588d99e6dba706011b6ccc2e615b88fe4350)
20:15 John Newbery and James O’Beirne are informed of the vulnerability so they can assist in alerting companies to a pending patch for a DoS vulnerability
20:30 Matt Corallo speaks with slushpool CTO and CEO and shares patch with disclosure of the Denial of Service
20:48 slushpool confirmed upgraded
21:08 Alert was sent to bitcoin ABC that a patch will be posted publicly by 22:00
21:30 (approx) Responded to original reporter with an acknowledgment
21:57 bitcoin Core PR 14247 published with patch and test demonstrating the Denial of Service bug
21:58 bitcoin ABC publishes their patch
22:07 Advisory email with link to bitcoin Core PR and patch goes out to Optech members, among others
23:21 bitcoin Core version 0.17.0rc4 tagged

September 18, 2018:

00:24 bitcoin Core version 0.16.3 tagged
20:44 bitcoin Core release binaries and release announcements were available
21:47 Bitcointalk and reddit have public banners urging people to upgrade

September 19, 2018:

14:06 The mailing list distributes an additional message urging people to upgrade by Pieter Wuille

September 20, 2018:

19:50 David Jaenson independently discovered the vulnerability, and it was reported to the bitcoin Core security contact email.

Published at Thu, 20 Sep 2018 04:00:00 +0000

December 9, 2017

NEO BEARS ARE FADING OUT AS NEM PRICE MORE THAN TRIPLE AFTER WECHAT INTEGRATION TECHNICAL ANALYSIS December 9, 2017

NEO bears are fading out which is encouraging for bulls who are now aiming at $45 after bouncing from the double bottoms and this week’s low. Other than NEO, NEM bears were obliterated after announcement of NEM-WeChat integration which would make it more accessible to chine. Otherwise, all other cryptocurrencies like DASH, IOTA and Monero are trending higher.

Let’s look at the charts:

NEM BULLS UP 150% AND CLEAR 61.8% FIBONACCI EXTENSION LEVEL

alt coin NEM Bulls chart technical analysis — *XEMUSD Weekly Chart for December 9, 2017*

After Poloniex dump, prices were cheap enough for whales to buy in at a discount. Anyhow, thanks to WeChat integration, NEM bulls are surging and aiming at the moon.

This is awesome news and as such NEM bulls are up 150% and market capitalization is past $4B making this cryptocurrency the cheapest in the top 10.

As we can see in the weekly chart, the first level of our Fibonacci extension at $0.59 has been hit and now, August’s highs of $0.36 is now our immediate support. NEM bulls should be looking for any dip as another buy opportunity.

DASH BULLS SURGE AND CLOSE ABOVE $670 SIGNALLING BULLS

alt coin DASH 4HR chart technical analysis — *DASHUSD 4HR Chart for December 9, 2017*

As per our trade recommendation, DASH bulls ended up leading the way and closing above our immediate resistance line at $670.

Even after a couple of testing support, price continued to make higher highs closing above the 20 period MA.

Therefore, at current prices and a stochastics buy signal in place, DASH is realigning itself and moving as per the weekly chart’s bullish trend.

In light of this, any break and close above this resistance line means we enter long. Better entry prices will definitely be found if there is a retest of support-previous resistance-after break out.

IOTA BULLS AIM AT $5.65

alt coin IOTA 4HR chart technical analysis — *IOTUSD 4HR Chart for December 9, 2017*

With any buy entry, the bulls get stronger and as it is, it is likely to surge past December 6 highs.

As we can see in the chart, after IOTA bulls picked up from our $3.2 support. To support this, price action has been strong and moving along the 20 period MA. There is also a stochastics buy signal in place.

We are certain that bulls are in charge just by looking at the diverging %k and %d of the stochastics which are almost parallel meaning many IOTA buyers are in the trade.

For now, short term traders should eye $5.65.

MONERO BULLS CLOSE IN ON $300

alt coin Monero chart technical analysis — *XMRUSD 4HR Chart for December 9, 2017*

As the chart shows, Monero bulls are in charge. Because of price action alignment in the higher time frame this bull trend might continue past $300.

First off, after that rebound from the 20 period MA, prices are moving higher but with strong bull momentum.

Moreover, stochastic signals are almost parallel and in sync with the weekly trend which is also bullish.

For now, any retest and bullish confirmation of the 20 period MA will represent a buy opportunity. Bull short term target is December 6 highs at around $300.

NEO BEARS ARE FADING OUT AS BULLS AIM AT $45

alt coin NEO BEARS Technical analysis — *NEOUSD 4HR Chart for December 9, 2017*

Even though NEO bears are fading out, bull movement is still low. NEO price action is inching higher and in fact it is trending above $34.

Additionally, judging from price action NEO bulls are likely to expand in coming days. Price action is bouncing from our double bottoms towards $45 which is around the upper limit of the W-formation.

Otherwise, buyers are in charge and we shall be taking long positions with stop losses tucked below $34.

All charts courtesy of Trading View

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