Your message dated Wed, 09 Jul 2025 13:05:31 +0000 with message-id <e1uzuun-00ce6m...@fasolo.debian.org> and subject line Bug#1109001: fixed in rust-sequoia-octopus-librnp 1.11.1-1 has caused the Debian Bug report #1109001, regarding rust-sequoia-octopus-librnp: denial of service via specially crafted compressed message to be marked as done.
This means that you claim that the problem has been dealt with. If this is not the case it is now your responsibility to reopen the Bug report if necessary, and/or fix the problem forthwith. (NB: If you are a system administrator and have no idea what this message is talking about, this may indicate a serious mail system misconfiguration somewhere. Please contact ow...@bugs.debian.org immediately.) -- 1109001: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1109001 Debian Bug Tracking System Contact ow...@bugs.debian.org with problems
--- Begin Message ---Package: rust-sequoia-octopus-librnp Version: 1.11.0-1 Severity: important Dear Maintainer, reported by codean via the YesWeHack bug bounty program: DoS via bzip2 decompression bomb Bug type: Denial of Service (CWE-400) Scope: octopus Endpoint: decompression mechanism Vulnerable part: Others Part name: BZip Payload: An openpgp message containing a specially crafted compressed message Technical env.: OS App. fingerprint: CVE: Impact: IP used: 0.0.0.0 Description The OpenPGP standard supports the use of a Compressed Data packet to include compressed content in OpenPGP messages. The sequoia-pgp implementation supports the zip, zlib, and bzip2 compression algorithms. Decompression for bzip2 is handled using the bzip2 library. This decompression function is applied directly to the compressed content without checking the size of the resulting decompressed payload. As a result, the library decompresses the entire content, regardless of size. This behavior is also present in octopus, the drop-in replacement for the RNP library used by Thunderbird. Because sequoia-pgp does not enforce size limits on OpenPGP messages and due to the very high compression ratio achievable with bzip2 (greater than 5,000,000), an attacker can craft a small message that, when processed by sequoia-pgp in octopus, causes CPU usage to spike to 100% for a significant amount of time. This leads to resource exhaustion and renders Thunderbird unresponsive. Similar behavior will occur in any application or library that makes use of sequoia-pgp in a single-threaded manner. The decompression factor could potentially be increased even further by using nested Compressed Data packets, but this was not tested. Impact An attacker is able to craft a PGP message that will force sequoia-pgp to drammatically increase the CPU usage, freezing the Thunderbird application when sequoia-octopus-librnp is used. Decompressing a 98KB message, which inflates to 20GB of uncompressed content, takes up to 3 minutes on an AMD Ryzen 7 PRO 7840U machine. While this applies to all supported compression algorithms, it has a significantly higher impact with bzip2, due to the much larger achievable compression ratio. Solution A suitable mitigation for libraries like sequoia-pgp is to implement a configurable size limit on the decompressed payload. This would help prevent Denial-of-Service attacks that exploit this behavior. Attachment: Proof of Concept In order to generate a small compressed PGP message we can use the following command, which will generate a 50KB ASCII-armored message with a 10GB decompressed payload: dd if=/dev/zero bs=1M status=none count=10240 | gpg --compress-algo BZIP2 --sign --armor --output dos_message.pgp.asc Once generated, send the content as the body of an email and open it using Thunderbird with sequoia-octopus-librnp installed. You will notice that the application freezes and CPU usage spikes. Triager Hello, We were able to reproduce the described behavior. A Decompression Bomb (or Zip Bomb) is a maliciously crafted compressed file designed to consume excessive system resources when decompressed, potentially leading to denial of service or application crashes. Because sequoia-pgp does not enforce size limits on OpenPGP messages and due to the very high compression ratio achievable with bzip2 (greater than 5,000,000), an attacker can craft a small message that, when processed by sequoia-pgp in octopus, causes CPU usage to spike to 100% for a significant amount of time. This leads to resource exhaustion and renders Thunderbird unresponsive. Similar behavior will occur in any application or library that makes use of sequoia-pgp in a single-threaded manner. Proof of Concept The attacker crafts a small compressed PGP message : dd if=/dev/zero bs=1M status=none count=10240 | gpg --compress-algo BZIP2 --sign --armor --output dos_message.pgp.asc This create a 50KB with a 10GB decompressed payload The attacker send this message as a body of an email The victims open the email using Thunderbird with sequoia-octopus-librnp https://crates.io/crates/sequoia-octopus-librnp#building-on-linux Then, attempt to decrypt the message and observe it dramatically increase the CPU usage, freezing the Thunderbird application. Note that the proposed CVSS score serves as a starting point to support further discussion. Please feel free to reach out if you'd like to review or adjust it. About the CVSS vector, it seems correct. -- cheers, Holger ⢀⣴⠾⠻⢶⣦⠀ ⣾⠁⢠⠒⠀⣿⡁ holger@(debian|reproducible-builds|layer-acht).org ⢿⡄⠘⠷⠚⠋⠀ OpenPGP: B8BF54137B09D35CF026FE9D 091AB856069AAA1C ⠈⠳⣄ It's the end of the world as we know it - and I feel fine.
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--- Begin Message ---Source: rust-sequoia-octopus-librnp Source-Version: 1.11.1-1 Done: Holger Levsen <hol...@debian.org> We believe that the bug you reported is fixed in the latest version of rust-sequoia-octopus-librnp, which is due to be installed in the Debian FTP archive. A summary of the changes between this version and the previous one is attached. Thank you for reporting the bug, which will now be closed. If you have further comments please address them to 1109...@bugs.debian.org, and the maintainer will reopen the bug report if appropriate. Debian distribution maintenance software pp. Holger Levsen <hol...@debian.org> (supplier of updated rust-sequoia-octopus-librnp package) (This message was generated automatically at their request; if you believe that there is a problem with it please contact the archive administrators by mailing ftpmas...@ftp-master.debian.org) -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 Format: 1.8 Date: Wed, 09 Jul 2025 14:49:09 +0200 Source: rust-sequoia-octopus-librnp Architecture: source Version: 1.11.1-1 Distribution: unstable Urgency: medium Maintainer: Debian Rust Maintainers <pkg-rust-maintain...@alioth-lists.debian.net> Changed-By: Holger Levsen <hol...@debian.org> Closes: 1109001 Changes: rust-sequoia-octopus-librnp (1.11.1-1) unstable; urgency=medium . * Package sequoia-octopus-librnp 1.11.1 from crates.io using debcargo 2.7.8 - Closes: #1109001. - refresh patches. Checksums-Sha1: 46cd817186275a65419b064a89a416cb470c417a 3876 rust-sequoia-octopus-librnp_1.11.1-1.dsc 29afad49ff7cdb67912e5b27587ca3054596c06f 155337 rust-sequoia-octopus-librnp_1.11.1.orig.tar.gz 870cebe7a577b4322ba6c3d8d5c71fb3ba1fd236 6160 rust-sequoia-octopus-librnp_1.11.1-1.debian.tar.xz 9a873d6f7950ee6c1ec106f4d9d82ccbade10b1d 7234 rust-sequoia-octopus-librnp_1.11.1-1_source.buildinfo Checksums-Sha256: 1397d2bfb1c7a383d4f3fa23e5df80b6e48e6234675b9d34839b19ed2503f896 3876 rust-sequoia-octopus-librnp_1.11.1-1.dsc 7cec5eac6fa7fa05b1eb301901bf5aa16bf950d352a98799157dd12af910e342 155337 rust-sequoia-octopus-librnp_1.11.1.orig.tar.gz 9cbd68f15cd7a5a062ca1083ea792261f21808d6c55613767ab69b463a69c9fd 6160 rust-sequoia-octopus-librnp_1.11.1-1.debian.tar.xz 7f1d4e02df0a03bb135d57bb2aab37349a2baa53a16af2dd23a6b2517f440d2e 7234 rust-sequoia-octopus-librnp_1.11.1-1_source.buildinfo Files: f858762e64b943befd49691a64a1c8d5 3876 rust optional rust-sequoia-octopus-librnp_1.11.1-1.dsc aa7b448967f4c8d40ab2604c5d30bdba 155337 rust optional rust-sequoia-octopus-librnp_1.11.1.orig.tar.gz fb2f49e83b5b72e97a434462f5b65c56 6160 rust optional rust-sequoia-octopus-librnp_1.11.1-1.debian.tar.xz b920cebaea2aa089a73c1f429e4615bd 7234 rust optional rust-sequoia-octopus-librnp_1.11.1-1_source.buildinfo -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEEuL9UE3sJ01zwJv6dCRq4VgaaqhwFAmhuZUgACgkQCRq4Vgaa qhzMxg//d0vKJKELQlKcOPX3wmBRc3Jl9OQpjolfmhcqk5ZbgZ634y092/9vroL0 s2MNxmQyXsUP83poG6UgIeKF3iRNtNX1Hq3pIdZyAg+JwH7PIe80u/YrUaG3zwgr uOo5Anmtxv+xafMtMTDlNUUtKOdFmUihr5Vg4PhvO+SB6qqd/WMVluN+ngeZ0f+j LbndLguHQEfW6pHmVE7CEhREt5vt+KaEpAvLWwLFvGf85r7Aw3zBX1Hi1+ESexMw dZu68n5Gp2KRypZiVws3FdFWBt54X66ATZ3Jy6ViHWGTVEd9iJ4VK1GsvPREKF1S 6fHXQwYmUFsCX1BFfTVrc8pXHt6OCszbVnINMnZN+Tifltrmw99UYGDe5dOwtYTA 8KCI3aLKejGTHI3zwbOW7TSX7py979FBFC5v1Dvt6z5jdT3fakklz7Xcm0zwfrkz IjmcEphKCJdHWumTZUeIm2i/dBM6xprKUHYegA3TCE8VbRoAmr91BUjJEQ7xfmMW XppSVP1HrUbRV6xpREjt4fx6iDY/VVGQWHw50HjkmWwxg5a1xbhks24DPBvRISxI 7q5ru0yyk7HuIMEaz21DI8jSIcvxISYunvRrdXugNFOzCxDzj+AB+eJueh5sf/N/ sHBzXp6ITIU9oLkVyJbVXkVj2EVsiNZtRYVCEuPVJOitYqxlu1k= =QUri -----END PGP SIGNATURE-----
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