FREAK is another serious flaw in the web's encryption
FREAK is another serious flaw in the web's encryption
By Jeremy Kirk
IDG News Service | Mar 3, 2015 4:25 PM PT
Experts are warning of a serious security flaw that has
apparently gone undetected for years and can weaken encrypted connections
between computers and websites, potentially undermining security across the
Internet.
The flaw, which has been dubbed FREAK, affects the widely
used Secure Sockets Layer protocol and its successor, Transport Layer Security,
and can allow an attacker to intercept supposedly encrypted traffic as it moves
between clients and servers.
The flaw affects many popular websites, as well as
programs including Apple’s Safari browser and Google’s Android mobile OS,
security experts say. Applications that use a version of OpenSSL prior to
1.0.1k are also vulnerable to the bug, detailed in this advisory.
The problem stems from export restrictions imposed by the
U.S. government in the early 1990s, which prohibited software makers from
shipping products with strong encryption overseas, wrote Ed Felten, professor
of computer science and public affairs at Princeton University.
That meant some companies shipped a version of their
products with weaker encryption keys for use overseas. When the law was changed
and it became legal to export stronger encryption, “the export mode feature was
not removed from the protocol because some software still depended on it,”
Felten wrote.
The vulnerability that has come to light now essentially
allows attackers to downgrade the security of connections from strong
encryption to that of the weaker, export-grade encryption.
Servers and devices that use OpenSSL, an open-source
encryption program, are vulnerable, including many Google and Apple devices,
embedded systems and other products, according to an advisory. Servers or
clients that accept the RSA_EXPORT cipher suites are at risk. FREAK stands for
Factoring attack on RSA-EXPORT Keys.
The keys can be downgraded by performing a
man-in-the-middle attack that interferes with the set-up process of an
encrypted connection. Although there are defenses in the SSL/TLS protocol to
prevent such tampering, they can be worked around. The weaker, 512-bit key can
be revealed using today’s powerful computers, and the data traffic can then be
decrypted.
Today’s protocols use longer encryption keys, and the
standard is 2,048-bit RSA. The 512-bit keys were considered secure two decades
ago, but an attacker could recover the key they need quite easily today using a
public cloud service.
“Back in the ‘90s, that would have required a heavy-duty
computation, but today it takes about seven hours on Amazon EC2 and costs about
$100,” Felten wrote.
Companies are moving fast to fix the issue. Akamai, a
content delivery network that supports a high number of websites, said it has
distributed a fix for its network.
However, some clients may still be vulnerable, wrote Bill
Brenner of Akamai.
“We can’t fix those clients, but we can avoid the problem
by disabling export ciphers,” he wrote. “Because this is a client side issue,
we’ve reached out to our customers and are working with them to make this
change.”
The vulnerability was discovered by Karthikeyan Bhargavan
of INRIA, a French science and technology research institute, and by Microsoft
Research. A technical paper describing FREAK is due to be presented at the
IEEE’s Security and Privacy conference in San Jose, California, in May.
Comments
Post a Comment