Re: CVE request: libcrypto++ - Timing Attack Counter Measure

[cve-assign () mitre org]

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> https://github.com/weidai11/cryptopp/issues/146

> > This counter measure seems to be removed by the compiler.

> > security bug

For "removed by the compiler" issues, sometimes the CVE is associated
with the upstream source code, and sometimes the CVE is associated
with a specific binary package that chose to compile in a way that was
unintended by the source-code authors. We feel that the former is the
best choice here.
https://github.com/weidai11/cryptopp/blob/master/Readme.txt says "The
following compilers are supported for this release ... GCC 3.3 - 5.2."
https://github.com/weidai11/cryptopp/blob/master/GNUmakefile mentions
the possibility of gcc -O3:

  # Aligned access required at -O3 for GCC
  ...
  ifeq ($(findstring -O3,$(CXXFLAGS)),-O3

issues/146 mentions "Debian compiles Crypto++ with the following
flags: -Wdate-time -D_FORTIFY_SOURCE=2 -g -O2 ...."

The gcc man page mentions:

  -O3 Optimize yet more.  -O3 turns on all optimizations specified by -O2

Thus, roughly speaking, it seems that all of Crypto++ had an
expectation of working with any recent version of gcc, even if (for
example) -O2 or -O3 is used. The "code to avoid timing attacks"
doesn't meet this expectation, and thus it's a vulnerability in
Crypto++. (It is not a vulnerability in the packaging within Debian or
any other distribution, and it is not a vulnerability in gcc.)

Use CVE-2016-3995 for this Crypto++ vulnerability.

(As a side note, Crypto++ is packaged for Fedora in the
cryptopp package, e.g., see the
http://pkgs.fedoraproject.org/cgit/rpms/cryptopp.git/tree/cryptopp.spec
page.)

- -- 
CVE Assignment Team
M/S M300, 202 Burlington Road, Bedford, MA 01730 USA
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