Bitcoin: AI detects 3 flaws capable of bringing down nodes

Coin Encyclopedia Improve your knowledge of cryptos

One allows you to crash a Windows or Mac node remotely. However, the project has long preferred silence on this type of matter: Bitcoin Core had waited two years to reveal a severe flaw. Here's what you need to know.

Bitcoin Core is the software used by most nodes, the computers that verify and relay each network transaction. The three security advisories published Wednesday describe three separate bugs.

Le plus sérieux, classé de gravité moyenne, touche Windows, macOS et BSD . A malicious peer connected to the node can force-feed it data until it saturates its memory. The developers talk about a node that can be “trivially crashed”.

The second, also of medium severity, causes memory to expand more slowly. Up to 2 MB per hour for each incoming connection, 5 MB for each outgoing connection.

The third is considered weak. It corrupts the undo files, those that the node keeps to undo the last blocks in the event of a chain reorganization.

It all starts with Project Loupe. This automated scan, led by Elias Rohrer at Spiral, entrusts the Bitcoin Core code to a language model. Each result then passes through the hands of a human developer, Gregory Sanders, before reaching the security team.

For the Windows and Mac flaw, the tool hit right on October 23. On Linux, Bitcoin Core monitors its connections with the poll() function. Elsewhere, it goes through select(), which continued to watch for "urgent data" from TCP, an old network protocol priority channel. It was enough to send some to get around the pause imposed on overly talkative peers.

The machine has also outstripped humans. Loupe a repéré le deuxième bug le 15 septembre , six jours avant le développeur L0rinc. For third, she had a lead of six weeks over L0rinc and three and a half months over Andrew Dorman.

It all depends on your machine. Nodes running Linux escape the main flaw, which only targets Windows, macOS and BSD.

The undo file bug is more vicious on certain systems. The code stored their position on 32 bits, so that a file larger than 4 GiB had its old data overwritten. On a 64-bit machine, a miner would have to spend around a month of the network's total output to mine it. The developers consider the scenario “impractical”.

Windows and 32-bit systems do not have this margin. The threshold drops to 2 GiB and the node shuts down on every reboot. FAT32 drives and 32-bit machines remain exposed even after the patch.

Machine-translated from French