RE: Microsoft Writing Secure Code

Hi Lawrence

Please explain what you mean with "...Given option 3 we know we can't trust the authentication routine.."

I am not understanding what you mean with this.

Regards
  Anton

-----Original Message-----
From: Lawrence Landauer (SECURITY)
[mailto:[email protected]]
Sent: 06 January 2005 09:05
To: priestmaster; Damhuis Anton
Subject: RE: Microsoft Writing Secure Code


None of the three options is secure. Given option 3 we know we can't
trust the authentication routine.  Given that: Option 1 gives the admin
info to anonymous or invalid users, Options 2 and 3 both let an attacker
brute force valid usernames?

- L

-----Original Message-----
From: priestmaster [mailto:[email protected]]
Sent: Thursday, January 06, 2005 8:16 AM
To: Damhuis Anton
Cc: [email protected]
Subject: Re: Microsoft Writing Secure Code

Hi,

The third is the most secure I think. If you know how exploitation of
vulnerabillites work, you can secure it easily. You need much security
knowledge to create complex and secure software. Security experts also
make mistakes and create security-releated bugs. No one is perfect.

greets,

priestmaster
----- Original Message -----
From: "Damhuis Anton" <[email protected]>
To: <[email protected]>
Cc: "Michael Howard" <[email protected]>
Sent: Tuesday, January 04, 2005 10:52 AM
Subject: RE: Microsoft Writing Secure Code



I have read the book "Designing Secure Web-based Applications", found it
quite informative but also somewhat disappointing.

I was (at the time) looking for a book that assists with "writing secure
code". Thus how code should be written, not the way code interfaces with
security components.

Example:
What is the best way to display User Details:

~~Suedo code Begin ~~
Option 1:
If var_userLevel = USER then
   ... display User info
else
  ... Display Admin Info
end if



Option 2:
If var_userLevel = ADMIN then
   ... display Admin info
else
  ... Display User Info Info
end if



Option 3:
If var_userLevel = ADMIN then
   ... display Admin info
elseif var_userLevel = USER
  ... Display User Info Info
else
  ... Capture Error
end if

~~Suedo code End~~


To me it is Option 3. Somewhat more work, but a lot more secure, then
Option 1. If for some reason someone else writes the code to get the
variable for var_userLevel , and that code is hackable, Option 3 will
withstand the attack a lot better then Option 1. Option 2 in this case
would also be better then Option 1, as Option 1 would display the Admin
info for anybody other then user. Option 2 in this case would revert
back to the lower level of access. Thus just structuring the If stament
differently in Option 1 and 2, already makes the code more secure.

Also by logging all the errors in option 3's last "Else" statement one
can look for any thing overlooked initially (and capture any unknown
hacker attacks -although this is reactively)

Regards
  Anton


Confidentiality Warning
=======================
The contents of this e-mail and any accompanying documentation are
confidential and any use thereof, in what ever form, by anyone other
than the addressee is strictly prohibited.



Confidentiality Warning
=======================

The contents of this e-mail and any accompanying documentation
are confidential and any use thereof, in what ever form, by anyone
other than the addressee is strictly prohibited.