RHSA-2003:063 - Security Advisory

Topic

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

[Updated 12 March 2003]
Added packages for Red Hat Enterprise Linux ES and Red Hat Enterprise
Linux WS

Description

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

In a paper, Brice Canvel, Alain Hiltgen, Serge Vaudenay, and Martin
Vuagnoux describe and demonstrate a timing-based attack on CBC ciphersuites
in SSL and TLS. An active attacker may be able to use timing observations
to distinguish between two different error cases: cipher padding errors and
MAC verification errors. Over multiple connections this can leak
sufficient information to be able to retrieve the plaintext of a common,
fixed block.

In order for an attack to be sucessful an attacker must be able to act as a
man-in-the-middle to intercept and modify multiple connections which all
involve a common fixed plaintext block (such as a password), and have good
network conditions that allow small changes in timing to be reliably observed.

These updated packages contain a patch provided by the OpenSSL group that
corrects this vulnerability.

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.

Please note that this update is available via Red Hat Network. 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 - 84597 - OpenSSL CBC timing attack

CVEs

• CVE-2003-0078

References

(none)