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FreeBSD-SA-01:44                                           Security Advisory
                                                                FreeBSD, Inc.

Topic:          gnupg contains format string vulnerability

Category:       ports
Module:         gnupg
Announced:      2001-07-10
Credits:        fish stiqz <fish@analog.org>
Affects:        Ports collection prior to the correction date.
Corrected:      2001-05-30
Vendor status:  Updated version released
FreeBSD only:   NO

I.   Background

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

II.  Problem Description

The gnupg port, versions prior to gnupg-1.0.6, contains a format
string vulnerability.  If gnupg attempts to decrypt a file whose
filename does not end in '.gpg', the filename is copied to the
prompt string, allowing a user-supplied format string.  This may allow
a malicious user to cause arbitrary code to be executed as the user
running gnupg.

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 5400 third-party applications in a ready-to-install
format. The ports collection shipped with FreeBSD 4.3 is vulnerable
to this problem since it was discovered after its release.

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

A malicious user supplying a file to be decrypted by the target user
running gnupg may be able to craft a filename causing arbitrary code
to be executed as the user running gnupg.

If you have not chosen to install the gnupg port/package, then
your system is not vulnerable to this problem.

IV.  Workaround

Deinstall the gnupg port/package if 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:

[i386]
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-4-stable/security/gnupg-1.0.6_1.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-5-current/security/gnupg-1.0.6_1.tgz

[alpha]
Packages are not automatically generated for the alpha architecture at
this time due to lack of build resources.

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-4-stable/devel/portcheckout-2.0.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-5-current/devel/portcheckout-2.0.tgz

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