[#48745] [ruby-trunk - Bug #7267][Open] Dir.glob on Mac OS X returns unexpected string encodings for unicode file names — "kennygrant (Kenny Grant)" <kennygrant@...>

17 messages 2012/11/02

[#48773] [ruby-trunk - Bug #7269][Open] Refinement doesn't work if using locate after method — "ko1 (Koichi Sasada)" <redmine@...>

12 messages 2012/11/03

[#48847] [ruby-trunk - Bug #7274][Open] UnboundMethods should be bindable to any object that is_a?(owner of the UnboundMethod) — "rits (First Last)" <redmine@...>

21 messages 2012/11/04

[#48854] [ruby-trunk - Bug #7276][Open] TestFile#test_utime failure — "jonforums (Jon Forums)" <redmine@...>

14 messages 2012/11/04

[#48988] [ruby-trunk - Feature #7292][Open] Enumerable#to_h — "marcandre (Marc-Andre Lafortune)" <ruby-core@...>

40 messages 2012/11/06

[#48997] [ruby-trunk - Feature #7297][Open] map_to alias for each_with_object — "nathan.f77 (Nathan Broadbent)" <nathan.f77@...>

19 messages 2012/11/06

[#49001] [ruby-trunk - Bug #7298][Open] Behavior of Enumerator.new different between 1.9.3 and 2.0.0 — "ayumin (Ayumu AIZAWA)" <ayumu.aizawa@...>

12 messages 2012/11/06

[#49018] [ruby-trunk - Feature #7299][Open] Ruby should not completely ignore blocks. — "marcandre (Marc-Andre Lafortune)" <ruby-core@...>

13 messages 2012/11/07

[#49044] [ruby-trunk - Bug #7304][Open] Random test failures around test_autoclose_true_closed_by_finalizer — "luislavena (Luis Lavena)" <luislavena@...>

11 messages 2012/11/07

[#49196] [ruby-trunk - Feature #7322][Open] Add a new operator name #>< for bit-wise "exclusive or" — "alexeymuranov (Alexey Muranov)" <redmine@...>

18 messages 2012/11/10

[#49211] [ruby-trunk - Feature #7328][Open] Move ** operator precedence under unary + and - — "boris_stitnicky (Boris Stitnicky)" <boris@...>

20 messages 2012/11/11

[#49229] [ruby-trunk - Bug #7331][Open] Set the precedence of unary `-` equal to the precedence `-`, same for `+` — "alexeymuranov (Alexey Muranov)" <redmine@...>

17 messages 2012/11/11

[#49256] [ruby-trunk - Feature #7336][Open] Flexiable OPerator Precedence — "trans (Thomas Sawyer)" <transfire@...>

18 messages 2012/11/12

[#49354] review open pull requests on github — Zachary Scott <zachary@...>

Could we get a review on any open pull requests on github before the

12 messages 2012/11/15
[#49355] Re: review open pull requests on github — "NARUSE, Yui" <naruse@...> 2012/11/15

2012/11/15 Zachary Scott <zachary@zacharyscott.net>:

[#49356] Re: review open pull requests on github — Zachary Scott <zachary@...> 2012/11/15

Ok, I was hoping one of the maintainers might want to.

[#49451] [ruby-trunk - Bug #7374][Open] File.expand_path resolving to first file/dir instead of absolute path — mdube@... (Martin Dubé) <mdube@...>

12 messages 2012/11/16

[#49463] [ruby-trunk - Feature #7375][Open] embedding libyaml in psych for Ruby 2.0 — "tenderlovemaking (Aaron Patterson)" <aaron@...>

21 messages 2012/11/16
[#49494] [ruby-trunk - Feature #7375] embedding libyaml in psych for Ruby 2.0 — "vo.x (Vit Ondruch)" <v.ondruch@...> 2012/11/17

[#49467] [ruby-trunk - Feature #7377][Open] #indetical? as an alias for #equal? — "aef (Alexander E. Fischer)" <aef@...>

13 messages 2012/11/17

[#49558] [ruby-trunk - Bug #7395][Open] Negative numbers can't be primes by definition — "zzak (Zachary Scott)" <zachary@...>

10 messages 2012/11/19

[#49566] [ruby-trunk - Feature #7400][Open] Incorporate OpenSSL tests from JRuby. — "zzak (Zachary Scott)" <zachary@...>

11 messages 2012/11/19

[#49770] [ruby-trunk - Feature #7414][Open] Now that const_get supports "Foo::Bar" syntax, so should const_defined?. — "robertgleeson (Robert Gleeson)" <rob@...>

9 messages 2012/11/20

[#49950] [ruby-trunk - Feature #7427][Assigned] Update Rubygems — "mame (Yusuke Endoh)" <mame@...>

17 messages 2012/11/24

[#50043] [ruby-trunk - Bug #7429][Open] Provide options for core collections to customize behavior — "headius (Charles Nutter)" <headius@...>

10 messages 2012/11/24

[#50092] [ruby-trunk - Feature #7434][Open] Allow caller_locations and backtrace_locations to receive negative params — "sam.saffron (Sam Saffron)" <sam.saffron@...>

21 messages 2012/11/25

[#50094] [ruby-trunk - Bug #7436][Open] Allow for a "granularity" flag for backtrace_locations — "sam.saffron (Sam Saffron)" <sam.saffron@...>

11 messages 2012/11/25

[#50207] [ruby-trunk - Bug #7445][Open] strptime('%s %z') doesn't work — "felipec (Felipe Contreras)" <felipe.contreras@...>

19 messages 2012/11/27

[#50424] [ruby-trunk - Bug #7485][Open] ruby cannot build on mingw32 due to missing __sync_val_compare_and_swap — "drbrain (Eric Hodel)" <drbrain@...7.net>

15 messages 2012/11/30

[#50429] [ruby-trunk - Feature #7487][Open] Cutting through the issues with Refinements — "trans (Thomas Sawyer)" <transfire@...>

13 messages 2012/11/30

[ruby-core:49792] [ruby-trunk - Feature #5741] Secure Erasure of Passwords

From: "MartinBosslet (Martin Bosslet)" <Martin.Bosslet@...>
Date: 2012-11-21 02:43:30 UTC
List: ruby-core #49792
Issue #5741 has been updated by MartinBosslet (Martin Bosslet).


FWIW, this feature is going to be an integral part of "binyo" (https://github.com/krypt/binyo).
----------------------------------------
Feature #5741: Secure Erasure of Passwords
https://bugs.ruby-lang.org/issues/5741#change-33373

Author: MartinBosslet (Martin Bosslet)
Status: Assigned
Priority: Normal
Assignee: matz (Yukihiro Matsumoto)
Category: 
Target version: 2.0.0


In other languages it is considered good practice to securely erase 
passwords immediately after they were used. Imagine authentication
in a web app - ultimately a String containing the password arrives
at the server, where it will be processed and compared to some 
previously stored value. After this is done, there is no need to
store these password Strings any longer, so they should be
discarded right away (more on why later).

In C, you would simply overwrite the array of bytes with zeroes or
random values. In Java, Strings are immutable, that's why there it
is common practice to use char[] for all things password and overwrite
them when done.

Currently, there is no way in Ruby to overwrite the memory that
was used by a String. String#clear and String#replace both use
str_discard internally, which only frees the underlying pointer 
without overwriting it.

The problem with not erasing passwords is this: the contents of the
String stay in memory until they are finally GC'ed. But even then
only the pointer will be freed, leaving the contents mostly intact
until the memory is reclaimed and overwritten later on.

This could be exploited if an attacker had access to the memory of
the server. This could happen in many ways: a core dump after a
crash, access to the host if the server runs in a VM, or even by
deep-freezing the DRAM :) [1]

It could be argued that given the examples above, much more 
devastating attacks would be possible since in all of those
cases you more or less have physical access to the machine. But
I would still consider this to be a valid concern, if not only
for the reason of never opening additional attack surfaces if
they can be avoided relatively easily.

I also found [2], which seems to show that Python deals with 
similar problems and it also contains more background info.

Eric Hodel and I discussed this yesterday and Eric came up with
a C extension that can be used to illustrate the problem (attached).

If you inspect the resulting core dump, you will find the following:

- the untouched String remains in memory fully intact
- the String#clear'ed String remains to a large extent, typically the
  first character is missing - so if you typed "PASSWORD", search for
  "ASSWORD" (unintentional pun) instead
- The String#clear_secure'ed will have been completely erased, no 
  traces remain

My questions:

1. Would you agree that we need this functionality?
2. Where would we ideally place it? I'm not sure whether
   String is the perfect place, but on the other hand, String
   is the only place where we have access to the implementation
   details.
3. Are there better alternative ways how we could achieve this?

[1] http://www.schneier.com/blog/archives/2008/02/cold_boot_attac.html
[2] http://stackoverflow.com/questions/728164/securely-erasing-password-in-memory-python


-- 
http://bugs.ruby-lang.org/

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