OpenSSL: SSL 2.0 protocol rollback

1. Gentoo Linux Security Advisory

Advisory Reference	GLSA 200510-11 / OpenSSL
Release Date	October 12, 2005
Latest Revision	November 07, 2005: 02
Impact	low
Exploitable	remote

Package	Vulnerable versions	Unaffected versions	Architecture(s)
dev-libs/openssl	< 0.9.7h	>= 0.9.7h, revision >= 0.9.7g-r1, revision >= 0.9.7e-r2	All supported architectures

Related bugreports: #108852

Synopsis

When using a specific option, OpenSSL can be forced to fallback to the less secure SSL 2.0 protocol.

2. Impact Information

Background

OpenSSL is a toolkit implementing the Secure Sockets Layer, Transport Layer Security protocols and a general-purpose cryptography library.

Description

Applications setting the SSL_OP_MSIE_SSLV2_RSA_PADDING option (or the SSL_OP_ALL option, that implies it) can be forced by a third-party to fallback to the less secure SSL 2.0 protocol, even if both parties support the more secure SSL 3.0 or TLS 1.0 protocols.

Impact

A man-in-the-middle attacker can weaken the encryption used to communicate between two parties, potentially revealing sensitive information.

3. Resolution Information

Workaround

If possible, disable the use of SSL 2.0 in all OpenSSL-enabled applications.

Resolution

All OpenSSL users should upgrade to the latest version:

Code Listing 3.1: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose dev-libs/openssl

4. References

Updated October 12, 2005

Summary: This is a Gentoo Linux Security Advisory

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