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Home » Hacking News » OpenPKG -SA-2003.020: mod_ssl RSA vulnerability

OpenPKG -SA-2003.020: mod_ssl RSA vulnerability

by Nikola Strahija on March 21st, 2003 A timing attack on OpenSSL has been researched by David Brumley. This attack allows local and remote attackers to extract the RSA private key of an SSL/TLS server like Apache/mod_ssl.


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________________________________________________________________________

OpenPKG Security Advisory The OpenPKG Project
http://www.openpkg.org/security.html http://www.openpkg.org
[email protected] [email protected]
OpenPKG-SA-2003.020 18-Mar-2003
________________________________________________________________________

Package: apache (option "with_mod_ssl" only)
Vulnerability: local and remote extraction of RSA private key
OpenPKG Specific: no

Affected Releases: Affected Packages: Corrected Packages:
OpenPKG CURRENT <= apache-1.3.27-20030305 >= apache-1.3.27-20030318
OpenPKG 1.2 <= apache-1.3.27-1.2.1 >= apache-1.3.27-1.2.2
OpenPKG 1.1 <= apache-1.3.26-1.1.3 >= apache-1.3.26-1.1.4

Dependent Packages: none

Description:
David Brumley and Dan Boneh of Stanford University have researched and
documented a timing attack on OpenSSL which allows local and remote
attackers to extract the RSA private key of an SSL/TLS server like
Apache/mod_ssl. [0] The OpenSSL [1] RSA implementation is generally
vulnerable to these type of attacks unless RSA blinding has been
turned on [2].

RSA blinding previously was not explicitly enabled by mod_ssl. If
Apache/mod_ssl is linked against the already fixed OpenSSL versions
(see security advisory OpenPKG-SA-2003.019 [3]), the problem is
already implicitly fixed inside OpenSSL. Nevertheless, mod_ssl 2.8.13
now explicitly enables RSA blinding for RSA private keys. For older
versions, we include this prevention change in OpenPKG, too.

Please check whether you are affected by running "/bin/rpm -q
apache" and "/bin/rpm -qi apache | grep with_mod_ssl". If you
have the "apache" package with option "with_mod_ssl" installed and its
version is affected (see above), we recommend that you immediately
upgrade (see Solution) [4][5].

Solution:
Select the updated source RPM appropriate for your OpenPKG release
[6][7], fetch it from the OpenPKG FTP service [8][9] or a mirror
location, verify its integrity [10], build a corresponding binary RPM
from it [4] and update your OpenPKG installation by applying the binary
RPM [5]. For the current release OpenPKG 1.2, perform the following
operations to permanently fix the security problem (for other releases
adjust accordingly).

$ ftp ftp.openpkg.org
ftp> bin
ftp> cd release/1.2/UPD
ftp> get apache-1.3.27-1.2.2.src.rpm
ftp> bye
$ /bin/rpm -v --checksig apache-1.3.27-1.2.2.src.rpm
$ /bin/rpm --rebuild apache-1.3.27-1.2.2.src.rpm
$ su -
# /bin/rpm -Fvh /RPM/PKG/apache-1.3.27-1.2.2.*.rpm
________________________________________________________________________

References:
[0] http://crypto.stanford.edu/~dabo/papers/ssl-timing.pdf
[1] http://www.openssl.org/
[2] http://www.openssl.org/news/secadv_20030317.txt
[3] http://www.openpkg.org/security/OpenPKG-SA-2003.019-openssl.html
[4] http://www.openpkg.org/tutorial.html#regular-source
[5] http://www.openpkg.org/tutorial.html#regular-binary
[6] ftp://ftp.openpkg.org/release/1.1/UPD/apache-1.3.26-1.1.4.src.rpm
[7] ftp://ftp.openpkg.org/release/1.2/UPD/apache-1.3.27-1.2.2.src.rpm
[8] ftp://ftp.openpkg.org/release/1.1/UPD/
[9] ftp://ftp.openpkg.org/release/1.2/UPD/
[10] http://www.openpkg.org/security.html#signature
________________________________________________________________________

For security reasons, this advisory was digitally signed with
the OpenPGP public key "OpenPKG " (ID 63C4CB9F)
of the OpenPKG project which you can find under the official URL
http://www.openpkg.org/openpkg.pgp or on http://keyserver.pgp.com/. To
check the integrity of this advisory, verify its digital signature by
using GnuPG (http://www.gnupg.org/). For instance, pipe this message to
the command "gpg --verify --keyserver keyserver.pgp.com".
________________________________________________________________________

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