Microsoft admits Freak SSL/TLS flaw affects all supported versions of Windows

HTTPS is not as secure as it might appear if it can be tricked into using old encryption standards

Microsoft has confirmed that all supported versions of Windows are affected by the ‘Freak’ SSL/TLS protocols flaw that came to light earlier this week.

It was thought at first that Windows systems were not affected, but Microsoft has now revealed that all versions of its supported operating system software are at risk from the flaw.

“Our investigation has verified that the vulnerability could allow an attacker to force the downgrading of the cipher suites used in an SSL/TLS connection on a Windows client system,” Microsoft said on a webpage about the flaw.

“The vulnerability facilitates exploitation of the publicly disclosed Freak technique, which is an industry-wide issue that is not specific to Windows operating systems.”

Microsoft said it had not received any information to suggest that any customers had been affected by Freak. It has also published a list of suggested workarounds, including disabling RSA key exchange ciphers.

Freak is an SSL/TLS vulnerability discovered by researchers who found  that it was possible to decrypt the HTTPS encryption protocols used between websites and browsers on Apple and Android devices.

The flaw has been dubbed Freak (Factoring attack on RSA-Export Keys) and information on the specifically created freakattack.com website explains that it works by forcing a mobile device browser to use an older, breakable encryption standard.

“The vulnerability allows attackers to intercept HTTPS connections between vulnerable clients and servers and force them to use ‘export-grade’ cryptography, which can then be decrypted or altered,” it said.

“Vulnerable clients include many Google and Apple devices (which use unpatched OpenSSL), a large number of embedded systems, and many other software products that use TLS behind the scenes without disabling the vulnerable cryptographic suites.”

The flaw was uncovered by a team of researchers at SmackTLS.com, who explained that the problem exists because of former US government policy concerning encryption technologies.

“This attack targets a class of deliberately weak export cipher suites. As the name implies, this class of algorithms has been introduced under the pressure of US governments agencies to ensure that the National Security Agency would be able to decrypt all foreign encrypted communication, while stronger algorithms were banned from export as they were classified as weapons of war.”

This means that attackers can force a server into deliberately using an encryption key that can be broken in about 12 hours.

“Thus, if a server is willing to negotiate an export cipher suite, a man-in-the-middle [attack] may trick a browser (which normally doesn’t allow it) to use a weak export key,” the team explained.

Numerous high-profile websites are affected by the flaw, such as americanexpress.com, groupon.com and whitehouse.gov. Overall, almost 10 percent of the Alexa top million websites could be affected.

V3 contacted Apple and Google for comment on the flaw but had received no reply at the time of publication.

F-Secure researcher Sean Sullivan told V3 that the discovery underlined the risks of trying to control technology like encryption, something that David Cameron has recently made noises about in the UK.

“In the 1990s there was this idea that they could control encryption and code as if it was a tangible thing and ban its export. Here we are 20 years later and you can see how that ideal has backfired,” he said.

“Cameron is making this same point today, but our reliance on encryption is only increasing and, if you try to introduce some ‘weaker’ standards that you want to control, it will come back to haunt you.”

Sullivan added that the risk to web users from the Freak flaw is more theoretical than anything else, as an attacker would need to compromise a website’s server and then force a device to accept the older standard.

Nevertheless, the incident demonstrates the risks posed by web browsers and the unintended consequences of trying to create two-tier technology systems.

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6 March 2015 | 10:16 am – Source: v3.co.uk

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