OpenBSD Project Finds Two Bugs In Software's IPsec ImplementationOpenBSD Project Finds Two Bugs In Software's IPsec Implementation
Up for debate: whether the FBI created a backdoor in the open-source operating system's code base
December 22, 2010
The OpenBSD project has found two bugs in how OpenBSD, a Unix-like open source operating system, implements Internet protocol security (IPsec).
The bugs are of interest given the recent allegation made by Gregory Perry, former CTO of now-defunct Federal Bureau of Investigation contractor Network Security Technology (NetSec), that the FBI created a backdoor in the OpenBSD code base, specifically in how it implements IPsec. He also alleged that multiple developers involved in contributing code to OpenBSD were on the payroll of NetSec, and that the FBI had hired it to create the backdoors.
Are the bugs a smoking gun? According to Theo de Raadt, the founder and leader of the OpenBSD project, one IPsec bug in OpenBSD relates to a "CBC oracle problem," and was fixed in the software crypto stack by Angelos Keromytis, the architect and primary developer for its IPsec, but ignored in device drivers, overseen by device driver author Jason Wright. Interestingly, both men had worked for NetSec, at different times.
"Neither Jason nor Angelos were working for NetSec at that time, so I think this was just an accident," said de Raadt. "Pretty serious accident."
Here's more information about the vulnerability: According to comments made by Thomas Ptacek, a security researcher at Matasano Security, on Hacker News, the CBC oracle problem refers to an approach to using ciphertext that was found to be insecure, because it used a previously used -- and thus predictable -- ciphertext block to begin encrypting a new message.
Meanwhile, "oracle" refers to "the condition that the server will encrypt a block of plaintext for the attacker, thus revealing the associated ciphertext," he said. But because an attacker could know how the plaintext is set to be encrypted, "that oracle can be used to attack any previous cipherblock."
Technical explanation aside, is this vulnerability exploitable? "This is a neat attack, but also a total pain in the a-- to use, and certainly not an FBI backdoor in OpenBSD IPsec," said Ptacek.
According to de Raadt, "I do not believe that either of these two problems, or other problems not yet spotted, are a result of clear malice. So far the issues we are digging up are a function of the time in history."
But he also said, "I believe that NetSec was probably contracted to write backdoors as alleged. If those were written, I don't believe they made it into our tree. They might have been deployed as their own product."
Regardless, he said that many parts of OpenBSD, including its IPsec implementation, have been getting a fresh look. "I am happy that people are taking the opportunity to audit an important part of the tree which many had assumed -- for far too long -- to be safe as it is."
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