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Matthew Green

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Given that we now know that the National Security Agency (NSA) has the ability to compromise some, if not all of VPN, SSL, and TLS forms of data transmission hardening, it’s worth considering the various vectors of technical and legal data-gathering that high-level adversaries in America and Britain (and likely other countries, at least in the “Five Eyes” group of anglophone allies) are likely using in parallel to go after a given target. So far, the possibilities include:

  • A company volunteers to help (and gets paid for it)
  • Spies copy the traffic directly off the fiber
  • A company complies under legal duress
  • Spies infiltrate a company
  • Spies coerce upstream companies to weaken crypto in their products/install backdoors
  • Spies brute force the crypto
  • Spies compromise a digital certificate
  • Spies hack a target computer directly, stealing keys and/or data, sabotage.

Let’s take these one at a time.

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Werwin15

Researchers have devised two new attacks on the Transport Layer Security and Secure Sockets Layer protocols, the widely used encryption schemes used to secure e-commerce transactions and other sensitive traffic on the Internet.

The pair of exploits—one presented at the just-convened 20th International Workshop on Fast Software Encryption and the other scheduled to be unveiled on Thursday at the Black Hat security conference in Amsterdam—don't pose an immediate threat to the millions of people who rely on the Web-encryption standards. Still, they're part of a growing constellation of attacks with names including BEAST, CRIME, and Lucky 13 that allow determined hackers to silently decrypt protected browser cookies used to log in to websites. Together, they underscore the fragility of the aging standards as they face an arsenal of increasingly sophisticated exploits.

"It illustrates how serious this is that there are so many attacks going on involving a protocol that's been around for years and that's so widely trusted and used," Matthew Green, a professor specializing in cryptography at Johns Hopkins University, told Ars. "The fact that you now have CRIME, BEAST, Lucky 13, and these new two attacks within the same week really illustrates what a problem we're facing."

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A representation of how TLS works.

Nadhem J. AlFardan and Kenneth G. Paterson

Software developers are racing to patch a recently discovered vulnerability that allows attackers to recover the plaintext of authentication cookies and other encrypted data as they travel over the Internet and other unsecured networks.

The discovery is significant because in many cases it makes it possible for attackers to completely subvert the protection provided by the secure sockets layer and transport layer protocols. Together, SSL, TLS, and a close TLS relative known as Datagram Transport Layer Security are the sole cryptographic means for websites to prove their authenticity and to encrypt data as it travels between end users and Web servers. The so-called "Lucky Thirteen" attacks devised by computer scientists to exploit the weaknesses work against virtually all open-source TLS implementations, and possibly implementations supported by Apple and Cisco Systems as well. (Microsoft told the researchers it has determined its software isn't susceptible.)

The attacks are extremely complex, so for the time being, average end users are probably more susceptible to attacks that use phishing e-mails or rely on fraudulently issued digital certificates to defeat the Web encryption protection. Nonetheless, the success of the cryptographers' exploits—including the full plaintext recovery of data protected by the widely used OpenSSL implementation—has clearly gotten the attention of the developers who maintain those programs. Already, the Opera browser and PolarSSL have been patched to plug the hole, and developers for OpenSSL, NSS, and CyaSSL are expected to issue updates soon.

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Enlarge / A diagram of a side-channel attack on a virtual machine. Using a malicious VM running on the same hardware, scientists were able to recover a private encryption key.

Zhang et al.

Piercing a key defense found in cloud environments such as Amazon's EC2 service, scientists have devised a virtual machine that can extract private cryptographic keys stored on a separate virtual machine when it resides on the same piece of hardware.

The technique, unveiled in a research paper published by computer scientists from the University of North Carolina, the University of Wisconsin, and RSA Laboratories, took several hours to recover the private key for a 4096-bit ElGamal-generated public key using the libgcrypt v.1.5.0 cryptographic library. The attack relied on "side-channel analysis," in which attackers crack a private key by studying the electromagnetic emanations, data caches, or other manifestations of the targeted cryptographic system.

One of the chief selling points of virtual machines is their ability to run a variety of tasks on a single computer rather than relying on a separate machine to run each one. Adding to the allure, engineers have long praised the ability of virtual machines to isolate separate tasks, so one can't eavesdrop or tamper with the other. Relying on fine-grained access control mechanisms that allow each task to run in its own secure environment, virtual machines have long been considered a safer alternative for cloud services that cater to the rigorous security requirements of multiple customers.

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An overview of a chosen-prefix collision

Marc Stevens

Flame

The Flame espionage malware that infected computers in Iran achieved mathematic breakthroughs that could only have been accomplished by world-class cryptographers, two of the world's foremost cryptography experts said.

"We have confirmed that Flame uses a yet unknown MD5 chosen-prefix collision attack," Marc Stevens and B.M.M. de Weger wrote in an e-mail posted to a cryptography discussion group earlier this week. "The collision attack itself is very interesting from a scientific viewpoint, and there are already some practical implications."

"Collision" attacks, in which two different sources of plaintext generate identical cryptographic hashes, have long been theorized. But it wasn't until late 2008 that a team of researchers made one truly practical. By using a bank of 200 PlayStation 3 consoles to find collisions in the MD5 algorithm—and exploiting weaknesses in the way secure sockets layer certificates were issued—they constructed a rogue certificate authority that was trusted by all major browsers and operating systems. Stevens, from the Centrum Wiskunde & Informatica in Amsterdam, and de Weger, of the Technische Universiteit Eindhoven were two of the driving forces behind the research that made it possible.

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