Disclosure of CPU/memory DoS due to many malicious peers (≤ version 0.20.0)

Bitcoin Core writes:
Disclosure of CPU/memory DoS due to many malicious peers (≤ version 0.20.0)

Bitcoin Core maintained an unlimited list of banned IP addresses and performed a quadratic operation
on it. This could lead to an OOM crash and a CPU Dos.

This issue is considered High severity.

Details

Bitcoin Core maintained a list of banned IP addresses. This list was not bounded and could be
manipulated by an adversary. Adding new entries to this list was particularly cheap for an attacker
when considering IPV6. In addition, when receiving a GETADDR message, Bitcoin Core would scan the
entire ban list for every single address to be returned (up to 2500).

Attribution

Calin Culianu first responsibly disclosed it. Calin later publicly disclosed the bug in a PR
comment
.

On the same day Jason Cox from Bitcoin ABC emailed the Bitcoin Core project to share this same
report they also received.

Timeline

  • 2020-06-08 Calin Culianu privately reports the bug to the Bitcoin Core project
  • 2020-06-08 Jason Cox privately shares the (same) report sent to Bitcoin ABC with Bitcoin Core
  • 2020-06-08 Calin Culianu publicly discloses the vulnerability on the original PR which introduced the quadratic behaviour
  • 2020-06-09 Pieter Wuille opens PR #19219 which fixes both the unbounded memory usage and the quadratic behaviour
  • 2020-06-16 Luke Dashjr gets assigned CVE-2020-14198 for this vulnerability after his request
  • 2020-07-07 Pieter’s PR is merged
  • 2020-08-01 Bitcoin Core 0.20.1 is released with the fix
  • 2021-01-14 Bitcoin Core 0.21.0 is released with the fix
  • 2022-04-25 The last vulnerable Bitcoin Core version (0.20.0) goes EOL
  • 2024-07-03 (Official) Public Disclosure