Home Security When F00F bug hit 20 years ago, Intel reacted the same way

When F00F bug hit 20 years ago, Intel reacted the same way

A little more than 20 years ago, Intel faced a problem with its processors, though it was not as big an issue as compared to the speculative execution bugs that were revealed this week.

The 1997 bug, which came to be known as the F00F bug, allowed a malicious person to freeze up Pentium MMX and "classic" Pentium computers. Any Intel Pentium/Pentium MMX could be remotely and anonymously caused to hang, merely by sending it the byte sequence "F0 0F C7 C8".

At the time, Intel said it learnt about the bug on 7 November 1997, but a report (which is now offline) said that at least two people had indicated on an Intel newsgroup that the company knew about it earlier before. The processor firm confirmed the existence on 10 November.

But, says veteran Linux sysadmin Rick Moen, the company's reaction to that bug was quite similar to the way it has reacted to this week's disclosures.

"Intel has a long history of trying to dissemble and misdirect their way out of paying for grave CPU flaws," Moen said in a post to the Linux Users of Victoria mailing list.

"Remember the 'Pentium Processor Invalid Instruction Erratum' of 1997, exposing all Intel Pentium and Pentium MMX CPUs to remote security attack, stopping them in their tracks if they could be induced to run processory instruction 'F0 0F C7 C8'?

"No, of course you don't. That's why Intel gave it the mind-numbingly boring official name 'Pentium Processor Invalid Instruction Erratum', hoping to replace its popular names 'F00F bug' and 'Halt-and-Catch Fire bug'."

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Moen, who is based in California, said that at the time, Intel's "judo-move response" was to create an information page claiming it dealt with the bug by linking to each of the various x86 OS vendors' bug-fix pages.

The company was effectively saying, "Here, we fixed the grave defect in our CPU by sitting on our asses and letting software coders work around our error," he wrote. "The press, of course, co-operated by simply pointing people to Intel's page and implying that Intel 'developed a fix'. That's what they're going to do this time, too, I'm sure of that."

In a detailed series of posts, from himself and many others, Moen has created a page about the F00F bug which he had put up on his own website.

He pointed out in a post on 1 March 1998, that Debian developer Robert Collins had notified Intel about the bug twice, months before it came to light on a Usenet posting. "Intel did nothing until an anonymous post from U. of Texas appeared on comp.os.linux.advocacy," Moen said. "News reports incorrectly claimed that the story broke on comp.sys.intel, and (tech news site) CNET rather pathetically credited itself."

He said that Intel had eventually opened a public relations Web page "rather soothingly dubbing the bug the 'Pentium Processor Invalid Instruction Erratum'. (Never say 'bug', and certainly never 'the Pentium bug'.) Intel released technical information only under non-disclosure, which helped BSDI release a binary-patch fix, which the Linux kernel team then reverse-engineered and implemented in improved form."

Moen, who can be caustic about the reaction of companies to situations such as this, noted in his post: "One interesting aspect of all this is how well both Intel and Microsoft have mastered the art of damage control via management of on-line bug information. This is really a much more serious bug than the infamous Pentium math bug, but never quite crossed over from geekdom into the public consciousness."

He said both companies had waited "until their more clueful customers' complaints reached an adequate volume, and then put up Web pages with mind-numbingly bureaucratic descriptions, that were as difficult to come across by accident as possible.

"This minimally placated the technical community, while avoiding alarming corporate executives, or even making them aware of the problem. With luck, the few who do stumble over the page will not recognise the problem or its severity, from the provided description."

Moen said this approach had been applied in other areas, too. "When Microsoft produced hotfixes that kinda-sorta addressed some (possibly not all) variants of the Ping of Death attack, the patch is classified as 'icmp-fix' and the symptom described as 'A Stop 0x0000000A occurs in Tcpip.sys when receiving Out of Band (OOB) data'.

"Doesn't sound much like 'An anonymous stranger crashes your system by sending it Ping of Death packets from somewhere halfway around the world", does it'?"

He noted in his March 1998 post that one would find less and less useful bug information by delving through FTP sites. "The vendors are tending not to see your serendipitous discoveries as being to their advantage. They prefer to keep a sharp eye on what you find and are interested in, accumulate mandatory survey information on you so they can spam your USPS and e-mailboxes, and present the appropriate spin on whatever knowledge they're obliged to give you.

"Welcome to 1998. We're from the Marketing department. We're here to help you."


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Sam Varghese

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A professional journalist with decades of experience, Sam for nine years used DOS and then Windows, which led him to start experimenting with GNU/Linux in 1998. Since then he has written widely about the use of both free and open source software, and the people behind the code. His personal blog is titled Irregular Expression.