RHSA-2003:102 - Security Advisory

Topic

Updated OpenSSL packages are available that fix a potential timing-based
attack and a modified Bleichenbacher attack.

[Updated 30 May 2003]
Added missing i686 packages.

Description

OpenSSL is a commercial-grade, full-featured, open source toolkit that
implements the Secure Sockets Layer (SSL v2/v3) and Transport Layer
Security (TLS v1) protocols, and provides a full-strength general purpose
cryptography library.

Researchers discovered a timing attack on RSA keys. Applications making
use of OpenSSL are generally vulnerable to such an attack, unless RSA
blinding has been turned on. OpenSSL does not use RSA blinding by default
and most applications do not enable RSA blinding.

A local or remote attacker could use this attack to obtain the server's
private key by determining factors using timing differences on (1) the
number of extra reductions during Montgomery reduction, and (2) the use of
different integer multiplication algorithms (Karatsuba and normal).

In order for an attack to be sucessful, an attacker must have good
network conditions that allow small changes in timing to be reliably
observed.

Additionally, the SSL and TLS components for OpenSSL allow remote attackers
to perform an unauthorized RSA private key operation via a modified
Bleichenbacher attack. This attack (also known as the Klima-Pokorny-Rosa
attack) uses a large number of SSL or TLS connections using PKCS #1 v1.5
padding to cause OpenSSL to leak information regarding the relationship
between ciphertext and the associated plaintext.

These erratum packages contain a patch provided by the OpenSSL group that
enables RSA blinding by default, and protects against the
Klima-Pokorny-Rosa attack.

Because server applications are affected by these vulnerabilities, we
advise users to restart all services that use OpenSSL functionality or,
alternatively, reboot their systems after installing these updates.

Solution

Before applying this update, make sure all previously released errata
relevant to your system have been applied.

To update all RPMs for your particular architecture, run:

rpm -Fvh [filenames]

where [filenames] is a list of the RPMs you wish to upgrade. Only those
RPMs which are currently installed will be updated. Those RPMs which are
not installed but included in the list will not be updated. Note that you
can also use wildcards (*.rpm) if your current directory *only* contains
the desired RPMs.

Please note that this update is also available via Red Hat Network. Many
people find this an easier way to apply updates. To use Red Hat Network,
launch the Red Hat Update Agent with the following command:

up2date

This will start an interactive process that will result in the appropriate
RPMs being upgraded on your system.

Affected Products

• Red Hat Enterprise Linux Server 2 ia64
• Red Hat Enterprise Linux Server 2 i386
• Red Hat Enterprise Linux Workstation 2 ia64
• Red Hat Enterprise Linux Workstation 2 i386

Fixes

• BZ - 86206 - New timing attack on OpenSSL applications

CVEs

• CVE-2003-0131
• CVE-2003-0147

References

(none)