Date:         Fri, 10 Nov 2000 14:45:11 -0800
From: FreeBSD Security Advisories <security-advisories@FREEBSD.ORG>
Subject:      FreeBSD Ports Security Advisory: FreeBSD-SA-00:67.gnupg
To: BUGTRAQ@SECURITYFOCUS.COM

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=============================================================================
FreeBSD-SA-00:67                                           Security Advisory
                                                                FreeBSD, Inc.

Topic:          gnupg fails to correctly verify signatures

Category:       ports
Module:         gnupg
Announced:      2000-11-10
Credits:        Jim Small <cavenewt@MY-DEJA.COM>
Affects:        Ports collection prior to the correction date.
Corrected:      2000-10-18
Vendor status:  Updated version released
FreeBSD only:   NO

I.   Background

GnuPG is an implementation of the PGP digital signature/encryption
protocol.

II.  Problem Description

Versions of gnupg prior to 1.04 fail to correctly verify multiple
signatures contained in a single document. Only the first signature
encountered is actually verified, meaning that other data with invalid
signatures (e.g. data which has been tampered with by an attacker)
will not be verified, and the entire document will be treated as
having valid signatures.

The gnupg port is not installed by default, nor is it "part of
FreeBSD" as such: it is part of the FreeBSD ports collection, which
contains over 4100 third-party applications in a ready-to-install
format. The ports collections shipped with FreeBSD 3.5.1 and 4.1.1 are
vulnerable to this problem since it was discovered after the releases,
but it was corrected prior to the release of FreeBSD 4.2.

FreeBSD makes no claim about the security of these third-party
applications, although an effort is underway to provide a security
audit of the most security-critical ports.

III. Impact

Documents containing multiple signed regions of data can be corrupted
or tampered with by an attacker without detection, as long as the
first signature in the document remains valid.

IV.  Workaround

Deinstall the gnupg port/package, if you you have installed it.

V.   Solution

One of the following:

1) Upgrade your entire ports collection and rebuild the gnupg port.

2) Deinstall the old package and install a new package dated after the
correction date, obtained from the following directories:

ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-3-stable/security/gnupg-1.04.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-4-stable/security/gnupg-1.04.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/alpha/packages-4-stable/security/gnupg-1.04.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-5-current/security/gnupg-1.04.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/alpha/packages-5-current/security/gnupg-1.04.tgz

3) download a new port skeleton for the gnupg port from:

http://www.freebsd.org/ports/

and use it to rebuild the port.

4) Use the portcheckout utility to automate option (3) above. The
portcheckout port is available in /usr/ports/devel/portcheckout or the
package can be obtained from:

ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-3-stable/devel/portcheckout-2.0.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-4-stable/devel/portcheckout-2.0.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/alpha/packages-4-stable/devel/portcheckout-2.0.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-5-current/devel/portcheckout-2.0.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/alpha/packages-5-current/devel/portcheckout-2.0.tgz
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Comment: For info see http://www.gnupg.org

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