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TLS/SSL Server Supports SSLv2

Severity CVSS Published Added Modified
6 (AV:N/AC:M/Au:N/C:P/I:P/A:N) January 01, 1996 February 09, 2009 October 11, 2013

Description

Although the server accepts clients using TLS or SSLv3, it also accepts clients using SSLv2. SSLv2 is an older implementation of the Secure Sockets Layer protocol. It suffers from a number of security flaws allowing attackers to capture and alter information passed between a client and the server, including the following weaknesses:

  • No protection from against man-in-the-middle attacks during the handshake.
  • Weak MAC construction and MAC relying solely on the MD5 hash function.
  • Exportable cipher suites unnecessarily weaken the MACs
  • Same cryptographic keys used for message authentication and encryption.
  • Vulnerable to truncation attacks by forged TCP FIN packets

SSLv2 has been deprecated and is no longer recommended. Note that neither SSLv2 nor SSLv3 meet the U.S. FIPS 140-2 standard, which governs cryptographic modules for use in federal information systems. Only the newer TLS (Transport Layer Security) protocol meets FIPS 140-2 requirements. In addition, the presence of an SSLv2-only service on a host is deemed a failure by the PCI (Payment Card Industry) Data Security Standard.

Note that this vulnerability will be reported when the remote server supports SSLv2 regardless of whether TLS or SSLv3 are also supported.

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References

Solution

  • Apache HTTPD

    Disable SSLv2 protocol support in Apache HTTPD

    For Apache web servers with mod_ssl, edit the Apache configuration file and change the SSLCipherSuite line to read:

    SSLCipherSuite ALL:!ADH:RC4+RSA:+HIGH:!SSLv2

    The ! (exclamation point) before SSLv2 is what disables this protocol.

  • Windows

    Disable SSLv2 protocol support in Microsoft Windows

    Configure the server to require clients to use at least SSLv3 or TLS.

    For Microsoft Windows before Windows 2003, see KB187498. For newer versions of Microsoft Windows, see KB245030.