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Debian Security Advisory: two gpg problems

Dec 25, 2000, 05:27 (0 Talkback[s])

Date: Mon, 25 Dec 2000 05:34:02 +0100
From: Wichert Akkerman wichert@cistron.nl
To: debian-security-announce@lists.debian.org
Subject: [SECURITY] [DSA-010-1] two gpg problems

Debian Security Advisory DSA-010-1                              security@debian.org
http://www.debian.org/security/                           Wichert Akkerman 
December 25, 2000

Package        : gnupg
Problem type   : cheating with detached signatures,
                 circumvention of web of trust
Debian-specific: no
Two bugs in GnuPG have recently been found:

1. false positives when verifying detached signatures

There is a problem in the way gpg checks detached signatures which can lead to false positives. Detached signature can be verified with a command like this:

gpg --verify detached.sig < mydata

If someone replaced detached.sig with a signed text (ie not a detached signature) and then modified mydata gpg would still report a successfully verified signature.

To fix the way the --verify option works has been changes: it now needs two options when verifying detached signatures: both the file with the detached signature, and the file with the data to be verified. Please note that this makes it incompatible with older versions!

2. secret keys are silently imported

Florian Weimer discovered that gpg would import secret keys from key-servers. Since gpg considers public keys corresponding to known secret keys to be ultimately trusted an attacked can use this circumvent the web of trust.

To fix this a new option was added to to tell gpg it is allowed to import secret keys: --allow-key-import.

Both these fixes are in version 1.0.4-1.1 and we recommend that you upgrade your gnupg package immediately.

wget url
        will fetch the file for you
dpkg -i file.deb
        will install the referenced file.
Debian GNU/Linux 2.2 alias potato

Potato was released for alpha, arm, i386, m68k, powerpc and sparc.

Source archives:
http://security.debian.org/dists/stable/updates/main/source/gnupg_1.0.4-1.1.diff.gz MD5 checksum: 3e6a792f3bbb566650ea37a286feedf4
http://security.debian.org/dists/stable/updates/main/source/gnupg_1.0.4-1.1.dsc MD5 checksum: 866059ad036f47c59bad9e5c3a0f0749
http://security.debian.org/dists/stable/updates/main/source/gnupg_1.0.4.orig.tar.gz MD5 checksum: bef2267bfe9b74a00906a78db34437f9

Alpha architecture:
http://security.debian.org/dists/stable/updates/main/binary-alpha/gnupg_1.0.4-1.1_alpha.deb MD5 checksum: 616e391a4eb5561bf32714e40bed38c5

ARM architecture:
http://security.debian.org/dists/stable/updates/main/binary-arm/gnupg_1.0.4-1.1_arm.deb MD5 checksum: e496f7aed98098feef2869be81b774b7

Intel ia32 architecture:
http://security.debian.org/dists/stable/updates/main/binary-i386/gnupg_1.0.4-1.1_i386.deb MD5 checksum: a6c0494c737250b0ccc7dc33056d8e7c

Motorola 680x0 architecture:
http://security.debian.org/dists/stable/updates/main/binary-m68k/gnupg_1.0.4-1.1_m68k.deb MD5 checksum: a07cbf5bce2890fe85cfae4d796c5b0d

PowerPC architecture:
http://security.debian.org/dists/stable/updates/main/binary-powerpc/gnupg_1.0.4-1.1_powerpc.deb MD5 checksum: e251364c24066cc88a3de11b4ba23275

Sun Sparc architecture:
http://security.debian.org/dists/stable/updates/main/binary-sparc/gnupg_1.0.4-1.1_sparc.deb MD5 checksum: b15f4ad07949fb0fa24a221b656691ae

These files will be moved into
ftp://ftp.debian.org/debian/dists/stable/*/binary-$arch/ soon.

For not yet released architectures please refer to the appropriate directory
ftp://ftp.debian.org/debian/dists/sid/binary-$arch/ .

apt-get: deb http://security.debian.org/ stable/updates main
dpkg-ftp: ftp://security.debian.org/debian-security dists/stable/updates/main
Mailing list: debian-security-announce@lists.debian.org

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