AES Encryption Cracked

CRYPTOGRAPHY RESEARCHERS have identified a weakness in the Advanced Encryption Standard (AES) security algorithm that can crack secret keys faster than before.

The crack is the work of a trio of researchers at universities and Microsoft, and involved a lot of cryptanalysis – which is somewhat reassuring – and still does not present much of a real security threat.

Andrey Bogdanov, from K.U.Leuven (Katholieke Universiteit Leuven), Dmitry Khovratovich, who is full time at Microsoft Research, and Christian Rechberger at ENS Paris were the researchers.

Although there have been other attacks on the key based AES security system none have really come close, according to the researchers. But this new attack does and can be used against all versions of AES.

This is not to say that anyone is in immediate danger and, according to Bogdanov, although it is four times easier to carry out it is still something of an involved procedure.

Recovering a key is no five minute job and despite being four times easier than other methods the number of steps required to crack AES-128 is an 8 followed by 37 zeroes.

“To put this into perspective: on a trillion machines, that each could test a billion keys per second, it would take more than two billion years to recover an AES-128 key,” the Leuven University researcher added. “Because of these huge complexities, the attack has no practical implications on the security of user data.” Andrey Bogdanov told The INQUIRER that a “practical” AES crack is still far off but added that the work uncovered more about the standard than was known before.

“Indeed, we are even not close to a practical break of AES at the moment. However, our results do shed some light into the internal structure of AES and indicate where some limits of the AES design are,” he said.

He added that the advance is still significant, and is a notable progression over other work in the area.

“The result is the first theoretical break of the Advanced Encryption Standard – the de facto worldwide encryption standard,” he explained. “Cryptologists have been working hard on this challenge but with only limited progress so far: 7 out of 10 for AES-128 as well as 8 out of 12 for AES-192 and 8 out of 14 rounds for AES-256 were previously attacked. So our attack is the first result on the full AES algorithm.”

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“TDL-4″ Botnet Is Practically Indestructible

A new and improved botnet that has infected more than four million computers is “practically indestructible,” software security experts say.

“TDL-4,” the name for both the bot Trojan that infects PCs and the ensuing collection of compromised computers, is “the most sophisticated threat today,” said Kaspersky Labs researcher Sergey Golovanov in a detailed analysis Monday.

“[TDL-4] is practically indestructible,” Golovanov said and others agree.

“I wouldn’t say it’s perfectly indestructible, but it is pretty much indestructible,” said Joe Stewart, director of malware research at Dell SecureWorks and an internationally-known botnet expert, in an interview today. “It does a very good job of maintaining itself.”

Golovanov and Stewart based their assessments on a variety of TDL-4′s traits, all which make it an extremely tough character to detect, delete, suppress or eradicate.

Because TDL-4 installs its rootkit on the Master Boot Record (MBR), it is invisible to both the operating system and more, importantly, security software designed to sniff out malicious code.

Further,what makes the botnet indestructible is the combination of its advanced encryption and the use of a public peer-to-peer (P2P) network for the instructions issued to the malware by command-and-control (C&C) servers.

“The way peer-to-peer is used for TDL-4 will make it extremely hard to take down this botnet,” said Roel Schouwenberg, senior malware researcher at Kaspersky, ”The TDL guys are doing their utmost not to become the next gang to lose their botnet.”

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