Gentoo: openssl timing based attack vulnerability
Posted by LinuxSecurity.com Team   
Gentoo This update fixes a timing-based attack on CBC cipher suites used in SSL and TLS which OpenSSL was found to be vulnerable to.

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GENTOO LINUX SECURITY ANNOUNCEMENT 200302-10
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PACKAGE : openssl
SUMMARY : timing based attack
DATE    : 2003-02-20 17:28 UTC
EXPLOIT : remote

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From advisory:

"The attack assumes that multiple SSL or TLS connections involve a
common fixed plaintext block, such as a password.  An active attacker
can substitute specifically made-up ciphertext blocks for blocks sent
by legitimate SSL/TLS parties and measure the time until a response
arrives: SSL/TLS includes data authentication to ensure that such
modified ciphertext blocks will be rejected by the peer (and the
connection aborted), but the attacker may be able to use timing
observations to distinguish between two different error cases, namely
block cipher padding errors and MAC verification errors.  This is
sufficient for an adaptive attack that finally can obtain the complete
plaintext block."

Read the full advisory at: 
http://www.openssl.org/news/secadv_20030219.txt

SOLUTION

It is recommended that all Gentoo Linux users who are running
dev-libs/openssl upgrade to openssl-0.9.6i or openssl-0.9.7a
as follows:

emerge sync
emerge -u openssl
emerge clean

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aliz@gentoo.org - GnuPG key is available at  http://cvs.gentoo.org/~aliz
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