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Penetration Testing
mailing list archives
RE: Whitespace in passwords
From: "Bryan McAninch" <BMcAninch () PENSON COM>
Date: Mon, 19 Sep 2005 12:20:42 -0500
As I understand it, the central limit theorem states that a randomized brute force attempt only takes x^y/x or x^(y-1)
operations to crack a given keyspace, where x is the base (number of valid characters), y is the exponentiation
variable (length) and x^y is the keyspace (total combinations).
For example (pardon the formatting):
60^7/60 = 2799360000000/60 = 46656000000 -> 60^(7-1) = 60^6 = 46656000000 operations
86^7/86 = 34792782221696/86 = 404567235136 -> 86^(7-1) = 86^6 = 404567235136 operations
62^8/62 = 218340105584896/62 = 3521614606208 -> 62^(8-1) = 62^7 = 3521614606208 operations
86^8/86 = 2992179271065856/86 = 34792782221696 -> 86^(8-1) = 86^7 = 34792782221696 operations
36^14/36 = 6140942214464815497216/36 = 170581728179578208256 -> 36^(14-1)= 36^13 = 170581728179578208256 operations
This is why public key authentication is recommended over passwords authentication. Given a mere 1024-bit key, it would
theoretically take 2^1023 operations to crack the key:
2^1024 = (1.797693134862315907729305190789 * 10^308)/2 = 8.9884656743115795386465259539451 * 10^307 -> 10^1023 =
8.9884656743115795386465259539451 * 10^307
Taking the 36^14 password above and comparing it to a 1024-bit RSA keypair, you have the follwing difference:
(2^1023) - (36^13) = (8.9884656743115795386465259539451 * 10^307) - (170581728179578208256) =
8.9884656743115795386465259539451e * 10^307 more operations with a 1024-bit RSA keypair, quite a difference! :)
Cheers,
Bryan
-----Original Message-----
From: Tim [mailto:pand0ra.usa () gmail com]
Sent: Monday, September 12, 2005 01:01 PM
To: pen-test () securityfocus com
Subject: Re: Whitespace in passwords
It all about the math. Let's write it out, say you have a machine that runs 3,000,000 combinations per second (about a
1.6 GHz machine). In this example we will use the Windows LanMan Challange/Response (which is bad to begin with, but
the main key in this is that it does not use a salt).
60 possible characters and the password is 7 characters long.(no spaces)
60^7 = 2,799,360,000,000 = 10.8 days (A-Z, 0-9, special)
86 possible characters and the password is 7 characters long.(no spaces)
86^7 = 34,792,782,221,696 = 134.23 days (A-Z, a-z, 0-9, special)
62 possible characters and the password is 8 characters long.(no spaces)
62^8 = 218,340,105,584,896 = 2.3 years (A-Z, 0-9, special)
86 possible characters and the password is 8 characters long.(no spaces)
86^8 = 2992179271065856 = 31.62 years (A-Z, a-z, 0-9, special)
36 possible characters and the password is 14 characters long. (no spaces)
36^14 = 6,140,942,214,464,815,497,216 combinations = 64,909,333 years (a-z, 0-9) 2bigbrown1dogs (throw some special
characters in) We have 2 big brown dogs! (25 characters using numbers, upper and lower, and special cahracters, you do
the math). Microsoft Windows supports up to ~250 characters for the passwords/phrases.
The point here is that a 14 character all lowercase passphrase with numbers is millions of time more difficult that a
'strong' 8 character password with all sorts of characters. A space is just another character and don't believe that it
will protect you from getting your password cracked (security through obsecurity?). Also, keep in mind that if you use
a algo that has a salt and supports many characters you will be much better off. Instead of making things more complex
for your users (which also increses the risk of them posting their password on a stick-it note) make the passphrase
easy for them to remember.
Side note: Disable LanMan on all Windows machines if you are not running any Windows 95/98/ME machines. It is there for
backward compatability and is still enabled by default on Windows 2003 Servers.
On 9/11/05, dave kleiman <dave () isecureu com> wrote:
They also do not have a lot of the Extended ASCII characters:
http://www.securityfocus.com/archive/88/312263
Dave
-----Original Message-----
From: Steve.Cummings () barclayscapital com
[mailto:Steve.Cummings () barclayscapital com]
Sent: Thursday, September 08, 2005 12:54
To: AMeyers () msolgroup com; Anders.Thulin () tietoenator com;
homegrown () bryanallott net; pen-test () securityfocus com
Subject: Re: Whitespace in passwords
Alt characters are also pretty cool
Try alt 255 this is blank space
-----Original Message-----
From: Andrew Meyers <AMeyers () msolgroup com>
To: Anders Thulin <Anders.Thulin () tietoenator com>; bryan allott
<homegrown () bryanallott net>; pen-test () securityfocus com
<pen-test () securityfocus com>
Sent: Thu Sep 08 01:40:34 2005
Subject: RE: Whitespace in passwords
I like pass phrases better because crackers like john and l0pht, by
default, don't have white spaces in their list of characters.
-------------------
Andrew Meyers
Systems Engineer
Managed Solution
Email: ameyers () mssandiego com
Phone: 619-220-0544 x115
Fax: 619-220-0599
http://www.mssandiego.com
-----Original Message-----
From: Anders Thulin [mailto:Anders.Thulin () tietoenator com]
Sent: Wednesday, September 07, 2005 3:17 AM
To: bryan allott; pen-test () securityfocus com
Subject: RE: Whitespace in passwords
From: bryan allott [mailto:homegrown () bryanallott net]
to the misnomer "passWORD" rather than passPHRASE but it seems
that [most?] people choose passes that dont contain whitespaces,
Most people still stick to alphanumeric passwords, and most of
those are passwords where the digits are placed at the end.
Whitespace is probably not more special than any of the other
'specials' that appear on a standard keyboard. A problem is to know
just what those are -- a look at a keyboard may lead a user to think
the 'x' on the keypad is a different special character than the '*'.
my main question, re security, is wether the whitespace made the
password too vulnerable? [historically] and why this constraint is
introduced in many systems..
Tradition, probably. In environments where users are given fixed
passwords that they can't change themselves, space belongs together
with S58, O0, and Il1 to the characters that probably will be
misunderstood, and so cause calls to helpdesk.
Anything that is likely to cause a help-desk call is a no-no in
large environments.
Another aspect is regularity of user interface design:
should space be treated as significant when it appears first and
last in a string in general, say a Search field in a text editor or
a From- field in an e-mail program? If not, spaces first and last in
passwords will be assumed to be insignificant as well -- and so
become another source for helpdesk complaints.
Regularity pays off.
[but then, if
myth- why propogate it?]
Probably also a case that password are seldom documented in
detail, and few people are willing to sit down to find out details
by experiment.
(Windows NT hashes use the OEM character set ... which is another
source of documentation problems.) So instructions for password
construction tend to avoid mentioning characters that might be
troublesome, even though there are some important things to know.
For instance, dead accent keys (on my kbd ^ is one) usually don't
change the base character in a password, so 'pass' and 'pâss' may
produce the same password hash.
The most useful character to have in a reasonably modern Windows
password is EUR (Alt-Gr E on my kbd.) I suspect the reason why is
well known -- if not, I'll leave it as an exercize. I'm sure there
are similar 'oddities' on other password situations.
i'm thinking that whitespaces [if yr system can handle them, and
why not?] would add another measure of complexity in cracking
pwds?
Of course they do. But ... if you alredy have an adequate
password protection -- say, accounts are locked out after 25 failed
attempts per day regardless of source -- the extra complexity
doesn't add much protection. (If you have the password hashes,
security has already failed, and any attempt to add a last line of
defense in the form of password complexity is misguided: it's only a
question of time before the passwords are discovered, and that time
should not be left to users to ensure.)
Anders Thulin anders.thulin () tietoenator com 040-661 50 63
TietoEnator Telecom & Media AB, Box 85, SE-201 20 Malmö
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Check your website for vulnerabilities to SQL injection, Cross site
scripting and other web attacks before hackers do!
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----------------------------------------------------------------------
-------- Audit your website security with Acunetix Web Vulnerability
Scanner:
Hackers are concentrating their efforts on attacking applications on
your website. Up to 75% of cyber attacks are launched on shopping
carts, forms, login pages, dynamic content etc. Firewalls, SSL and
locked-down servers are futile against web application hacking. Check
your website for vulnerabilities to SQL injection, Cross site scripting and other web attacks before hackers do!
Download Trial at:
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---------
--
Tim Van Cleave
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launched on shopping carts, forms, login pages, dynamic content etc. Firewalls, SSL and locked-down servers are futile
against web application hacking. Check your website for vulnerabilities to SQL injection, Cross site scripting and
other web attacks before hackers do!
Download Trial at:
http://www.securityfocus.com/sponsor/pen-test_050831
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------------------------------------------------------------------------------
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Hackers are concentrating their efforts on attacking applications on your
website. Up to 75% of cyber attacks are launched on shopping carts, forms,
login pages, dynamic content etc. Firewalls, SSL and locked-down servers are
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to SQL injection, Cross site scripting and other web attacks before hackers do!
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