Fine grain Cross-VM Attacks on Xen and VMware (AES)

[Griffin Boyce]

'AES in a number popular cryptographic libraries including OpenSSL, 
PolarSSL and Libgcrypt are vulnerable to Bernstein’s correlation attack 
when run in Xen and VMware virtual machines, the most popular VMs used 
by cloud service providers.'

Abstract: http://eprint.iacr.org/2014/248
Paper: http://eprint.iacr.org/2014/248.pdf

So in a nutshell, if you want to steal a website's private keys, you can 
get an account on their hosting provider and at least have a shot at 
getting on the same physical server ;-)

~Griffin