VMware ESX Source Code Leaked Online -- Again

More source code for VMware's ESX hypervisor technology has been leaked onto the Internet.

The code, which dates back to 2004, is related to the posting of code back in April, according to VMware director of platform security Ian Mulholland. "It is possible that more related files will be posted in the future," he writes. "We take customer security seriously and have engaged our VMware Security Response Center to thoroughly investigate."

A hacker using the alias "Stun" posted on Twitter a link where the code could be downloaded. He wrote that while VMware would try to downplay the issue by pointing to the age of the code, "thanks god, there is still such as [sic] thing as reverse engineering that will prove it's true destiny."

"Little sidenote about this release," the alleged hacker writes, "it is the VMKernel from between 1998 and 2004, but as we all know, kernels don't change that much in programs, they get extended or adapted but some core functionality still stays the same."

The source of the April leak was widely believed to be a hacker by the name of "Hardcore Charlie," who also posted internal emails from VMware and claimed to have compromised a system belonging to the China Electronics Import-Export Corporation (CEIEC). At the time, VMware said the leak did not necessarily pose a risk to customers, and that it shares its source code and interfaces with other industry partners to "enable the broad virtualization ecosystem."

"Ensuring customer security is our top priority," VMware's Mulholland blogged Sunday. "As a matter of best practices with respect to security, VMware strongly encourages all customers to apply the latest product updates and security patches made available for their specific environment. We also recommend customers review our security hardening guides. By applying the combination of the most current product updates and the relevant security patches, we believe our customer environments will be best protected."

Earlier this year, hackers posted source code for Symantec's pcAnywhere software online after a failed extortion attempt.

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