Cross-VM Side-channel attacks against cryptography keys
Nov 05, 2012
A group of researchers has developed a side-channel attack targeting virtual machines that could pose a threat to cloud computing environments. Side-channel attacks against cryptography keys have, until now, been limited to physical machines, this attack is the first such attack demonstrated on a symmetric multiprocessing system virtualized using a modern VMM (Xen). A side channel is a form of information leakage that arises as a byproduct of resource exposure, such as the sharing of memory caches. A side-channel attack exploits such leakage to steal secrets, such as cryptographic keys. " In this attack, the researchers were able to extract a private ElGamal decryption key from the target VM's libgcrypt library; the target was running Gnu Privacy Guard. Over the course of a few hours of observations, they were able to reconstruct a 457-bit exponent accompanying a 4096-bit modulus with high accuracy. So high that the attacker was then left to search fewer than 10,000 possible...
