Date: Mon, 4 Jul 2022 01:31:18 -0400 From: Demi Marie Obenour <demi@...isiblethingslab.com> To: Open Source Software Security <oss-security@...ts.openwall.com> Subject: Denial of service in GnuPG GnuPG is vulnerable to a denial of service attack when processing crafted detached signatures and/or certificates. By concatenating the same signature to itself a very large number of times, and then wrapping them in a compressed packet, I am able to cause GnuPG to take over a minute to process an input that is less than 5KB armored. https://dev.gnupg.org/D556 should fix this particular bug by refusing to process compressed packets in detached signatures and/or certificates. There may be further problems with non-detached signatures that are not addressed by D556, but I recommend applying D556 first. Signature (of /dev/null) that triggers this bug is attached, along with the corresponding public key. -- Sincerely, Demi Marie Obenour (she/her/hers) Invisible Things Lab Download attachment "test-key.cert" of type "application/octet-stream" (1209 bytes) View attachment "decomp-3" of type "text/plain" (4604 bytes) Download attachment "signature.asc" of type "application/pgp-signature" (834 bytes)
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