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Re: Bugs found by Cryptofuzz - some missing CVEs or too low impact for CVE?


From: Robert Watson <robertcwatson1 () gmail com>
Date: Tue, 8 Dec 2020 17:18:04 -0500

Question from a retired programmer but security novice... Since fuzzing is
used to find bugs in other programs, doesn't it need to be held to a bit
higher standard in order to maintain credibility?

On Tue, Dec 8, 2020, 16:12 Eric Biggers <ebiggers () kernel org> wrote:

On Tue, Dec 08, 2020 at 08:01:14PM +0100, yersinia wrote:
At this link, multiple security bugs of various kinds are highlighted in
very widespread basic cryptographic applications, which have then been
corrected. I haven't done a deep analysis on all of them but I haven't
found any associated CVEs of some of them. Do I have to assume that they
weren't all that important or that the process of reporting them was
missing? Thanks

https://github.com/guidovranken/cryptofuzz

Fuzzing can easily find large numbers of bugs, and it's usually unclear
what the
security impact of them is.  So if people want CVEs, someone has to
actually put
the effort into analyzing each bug and (if applicable) filing for a CVE.
Presumably just no one has done that for the above bugs.

Something similar happened when I added fuzz tests to the Linux kernel's
crypto
API last year.  In less than a year they had resulted in over 100 bug
fixes.
Most didn't *seem* too concerning, e.g. most were bugs in crypto drivers
that
seemed to be rarely used, or crypto algorithms that seemed to be rarely
used, or
edge cases in the crypto API that seemed to be rarely or never encountered.

The bugs in userspace libraries found by cryptofuzz look somewhat
similar.  They
include some of the same kinds of bugs, like mishandling zero-length
inputs,
mishandling data passed in specific chunk sizes, or bugs in weird
algorithms.

However, in both cases it isn't possible to be certain of the impact and
applicability for a CVE of each bug without analyzing each bug in detail,
which
would be very time-consuming, and in general it's no one's job to do that.

Likewise, syzkaller has found thousands of Linux kernel bugs and most
haven't
had CVEs filed.

- Eric


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