Still reeling from Heartbleed, OpenSSL suffers from crypto bypass flaw

[InfoSec News <alerts () infosecnews org>]

http://arstechnica.com/security/2014/06/still-reeling-from-heartbleed-openssl-suffers-from-crypto-bypass-flaw/

By Dan Goodin
Ars Technica
June 5, 2014

A researcher has uncovered another severe vulnerability in the OpenSSL 
cryptographic library. It allows attackers to decrypt and modify Web, 
e-mail, and virtual private network traffic protected by the transport 
layer security (TLS) protocol, the Internet's most widely used method for 
encrypting traffic traveling between end users and servers.

The TLS bypass exploits work only when traffic is sent or received by a 
server running OpenSSL 1.0.1 and 1.0.2-beta1, maintainers of the 
open-source library warned in an advisory published Thursday. The advisory 
went on to say that servers running a version earlier than 1.0.1 should 
update as a precaution. The vulnerability has existed since the first 
release of OpenSSL, some 16 years ago. Library updates are available on 
the front page of the OpenSSL website. People who administer servers 
running OpenSSL should update as soon as possible.

The underlying vulnerability, formally cataloged as CVE-2014-0224, resides 
in the ChangeCipherSpec processing, according to an overview published 
Thursday by Lepidum, the software developer that discovered the flaw and 
reported it privately to OpenSSL. It makes it possible for attackers who 
can monitor a connection between an end user and server to force weak 
cryptographic keys on client devices. Attackers can then exploit those 
keys to decrypt the traffic or even modify the data before sending it to 
its intended destination.

"OpenSSL's ChangeCipherSpec processing has a serious vulnerability," the 
Lepidum advisory stated. "This vulnerability allows malicious intermediate 
nodes to intercept encrypted data and decrypt them while forcing SSL 
clients to use weak keys which are exposed to the malicious nodes. There 
are risks of tampering with the exploits on contents and authentication 
information over encrypted communication via web browsing, e-mail and VPN, 
when the software uses the affected version of OpenSSL."

Client devices are vulnerable no matter what older version of OpenSSL they 
are running. As stated earlier, servers are vulnerable when running 1.0.1 
and 1.0.2-bata1, according to an accompanying OpenSSL advisory. The 
attacks are possible only when both sides are running a vulnerable OpenSSL 
version.

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