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Security Update:Serious Security Flaw (DROWN) Affecting Essential Cryptographic Protocols

Status Type

Security Update

Date and Time

Tuesday, March 1, 2016 - 12:49

Reason

Security Update

Impact

Servers Running SSLv2

 

WHAT HAPPENED?

A serious security flaw has been discovered that affects HTTPS and other services that rely on SSL and TLS, some of the essential cryptographic protocols for Internet security. The attack has been dubbed DROWN (Decrypting RSA with Obsolete and Weakened eNcryption) and takes advantage of websites, mail servers, and other TLS-dependent services.

Advanced Users: For a complete description of the vulnerabilities and affected versions visit The Drown Attack - https://drownattack.com/.


IS MY SERVER VULNERABLE?

A server is vulnerable to DROWN if:

  • It allows SSLv2 connections.

This is surprisingly common, due to misconfiguration and inappropriate default settings.

or:

  • Its private key is used on any other server that allows SSLv2 connections, even for another protocol.

For example: if the email server supports SSLv2 and the web server does not, an attacker can take advantage of the email server to break TLS connections to the web server.


WHAT'S THE PROBLEM?

The problem exists because many HTTPS servers still support the old and insecure SSL (Secure Sockets Layer) version 2 protocol.

  • SSLv2 was superseded by SSLv3 in 1996, but only officially deprecated in 2011.
  • SSLv3 was replaced, too, by the more modern TLS (Transport Layer Security) versions 1.0, 1.1 and 1.2.


WHAT CAN THE ATTACKERS GAIN?

Any communication between users and the server. This typically includes, but is not limited to, usernames and passwords, credit card numbers, emails, instant messages, and sensitive documents.


WHAT DO I NEED TO DO?

1. Server Administrators


2. General User

  • No action required.


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