[Pkg-openssl-devel] Bug#333500: CAN-2005-2969: Potential SSL2 fallback

Moritz Muehlenhoff jmm at inutil.org
Wed Oct 12 08:18:25 UTC 2005


Package: openssl
Version: 0.9.8-2
Severity: important
Tags: security

Yutaka Oiwa found a vulnerability in OpenSSL:

A vulnerability has been found in all previously released versions of
OpenSSL (all versions up to 0.9.7h and 0.9.8a).  Versions 0.9.7h and
0.9.8a have been released to address the issue.  The vulnerability
potentially affects applications that use the SSL/TLS server
implementation provided by OpenSSL.

Such applications are affected if they use the option
SSL_OP_MSIE_SSLV2_RSA_PADDING.  This option is implied by use of
SSL_OP_ALL, which is intended to work around various bugs in
third-party software that might prevent interoperability.  The
SSL_OP_MSIE_SSLV2_RSA_PADDING option disables a verification step in
the SSL 2.0 server supposed to prevent active protocol-version
rollback attacks.  With this verification step disabled, an attacker
acting as a "man in the middle" can force a client and a server to
negotiate the SSL 2.0 protocol even if these parties both support SSL
3.0 or TLS 1.0.  The SSL 2.0 protocol is known to have severe
cryptographic weaknesses and is supported as a fallback only.

Applications using neither SSL_OP_MSIE_SSLV2_RSA_PADDING nor
SSL_OP_ALL are not affected.  Also, applications that disable
use of SSL 2.0 are not affected.

Please see http://www.openssl.org/news/secadv_20051011.txt for the
full advisory, which contains patches for 0.9.7 and 0.9.8.

This has been assigned CAN-2005-2969, please mention so in the changelog
when fixing this.

Cheers,
        Moritz


-- System Information:
Debian Release: testing/unstable
  APT prefers unstable
  APT policy: (500, 'unstable')
Architecture: i386 (i686)
Shell:  /bin/sh linked to /bin/bash
Kernel: Linux 2.6.14-rc1
Locale: LANG=C, LC_CTYPE=de_DE.ISO-8859-15 at euro (charmap=ISO-8859-15)

Versions of packages openssl depends on:
ii  libc6                         2.3.5-6    GNU C Library: Shared libraries an
ii  libssl0.9.8                   0.9.8-2    SSL shared libraries

openssl recommends no packages.

-- no debconf information




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