Re: Of the three expensive vulnerability scanners

[Adam Shostack <adam () homeport org>]

Sounds lovely, and I've been in places where we tried to make it work,
with more developer training, more resources to answer questions
early, etc.  But who's going to pay for it?  If you're an exec who's
being asked to sign off on an extra resource for securing the new
product, what's the ROI?  Who's going to make promises about how much
more secure something will be?  If I add Alice to a team of 10
developers, and Alice's job is security, what measurable benefit does
that have?

The "test at the end" has short-term economic and political benefits
for the people who get to make a cheap end run around their security
people.

I'm not arguing for this approach. I'm looking for business-driven
arguments to beat it.

Adam

On Tue, Nov 23, 2004 at 08:50:01AM +1100, Michael Silk wrote:
| Hi,
| 
|       How about this crazy idea ... Analyse it *AS* it is being
| developed, not after.
| 
|       Companies should really stop processing out "millions of lines
| of code" and then "securing" it by analysing it with some tool or
| bringing it some "expert" to review it before it's deployed. There would
| be many political issues with such analysing before deployment .. (i.e:
| "we found bugs". "I don't care, it needs to go live, we promised the
| customers ...").
| 
|       If, instead, it's analysed at the time of development it solves
| all these problems. And then sure, these analysers could be used
| occasionally through-out the development cycle to pick up the oversight
| from some developer, but at least they wouldn't be the last line.
| 
| -- Michael 
| 
| -----Original Message-----
| From: Adam Shostack [mailto:adam () homeport org] 
| Sent: Monday, 22 November 2004 6:47 AM
| To: ban.marketing.bs () hushmail com
| Cc: webappsec () securityfocus com
| Subject: Re: Of the three expensive vulnerability scanners
| 
| I know of companies that deploy millions of lines of new code annually.
| (Both in house and outsourced code)  Deciding what to have an expert
| look at is hard and slow.  Adding any automation makes their experts
| more effective.
| 
| So you need do decide between static testing, dynamic testing, or some
| mix.  Static testing is very good at finding some things, but not
| others.  It finds strcats, but doesn't find a lack of authentication.
| (I like to think of these as sins of commission vs. sins of
| ommission.)
| 
| I'm not going to argue for or against the commercial dynamic test
| tools...I just don't know enough about them.  But dynamic testing is not
| fundamentally flawed, its a potentially useful part of a toolset.
| Would you not nmap and nikto boxes before they go out, just as a sanity
| check?
| 
| Adam
| 
| 
| On Tue, Nov 16, 2004 at 06:14:28PM -0800, ban.marketing.bs () hushmail com
| wrote:
| | OK what am I missing here? Why use a fundamentlaly floored technique 
| | for finding the issue? Why not look at the source? Its pretty damn 
| | obvious where you are reading or writing unvalidated data....please 
| | please no "source is not always available"
| | junk.....this is the web and 99% your looking at bespoke apps. You 
| | have to ask or educate the client at worse.
| | 
| | Its about time the industry started taking software security seriously
| 
| | and continuing down this futile route of refining pen testing 
| | techniques to make up for the obvious limitations of this technique is
| 
| | not it IMHO.
| | 
| | Newsflash - Most serious XSS issues in the real world are stored not 
| | refelcted and unless you can trace data to the reflection point this 
| | technique will NEVER find them !
| | 
| | 
| | 
| | In-Reply-To: <003801c4c9c6$e5f39530$8d8606d1@rockstar>
| | 
| | Jim,
| | 
| | The problems you've mentioned with regard to the Cross Site Scripting 
| | tests point to a functionality area where the major players in the App
| 
| | security market need major improvement. As Jeremiah pointed out, the 
| | problem is broader than XSS policies alone, but it certainly affects 
| | them.
| | 
| | One reason the XSS policies yield diminishing returns and are poorly 
| | organized in reports is due in part I believe to a lack of proper 
| | detection mechanisms. Both products use a plethora of fault injection 
| | techniques, yet neither seems sensitive to whether or not the injected
| 
| | script is returned within the context of the app's response in a form 
| | that is executable by a browser. As a result, when one form field is 
| | vulnerable to XSS, you can get into situations where virtually every 
| | XSS test returns with a positive detection.
| | 
| | As you've no doubt noticed, each product checks for various kinds of 
| | XSS, some of these kinds are distinguished on the basis of the 
| | delimiter that is used. Despite the technical differences, each 
| | delimiter type has a sophisticated name (i.e Double Quote Single Quote
| 
| | Bracket kung fu,
| | etc.)
| | 
| | ">&lt;script ....
| | '>&lt;script ....
| | ">">&lt;script ...
| | <--&lt;script ...
| | <textarea>&lt;script ...
| | etc.
| | 
| | While the main vulnerability condition is whether or not an 
| | application will "echo back" the script sequences, real problem is 
| | that the different delimiters are important because some will execute 
| | when returned by the application, and others will not, depending upon 
| | the HTML/Script code of the application. This is why it is important 
| | to audit the application's logic, but there really is no reason to 
| | test for 12 different types of cross site scripting scenarios using 
| | different delimiters and script types if the detection mechanism can't
| 
| | account for which sequences actually yield results that are 
| | executable.
| | 
| | The optimal solution in my opinion would be to emulate a browser and 
| | trap for alerts (or other events) and then to organize the report data
| 
| | based on which delimiters successfully generated the desired pop-ups 
| | (or whatever event is trapped for). The rest could be classified as 
| | warnings.
| | This would
| | help to minimize the multiple alerting problems that plague the XSS 
| | tests and produce frequently confusing results. While this wouldn't 
| | fix the reporting problems, it would help to attenuate the signal.
| | 
| | -tom
| | 
| | 
| | 
| | 
| | 
| | Concerned about your privacy? Follow this link to get secure FREE 
| | email: http://www.hushmail.com/?l=2
| | 
| | Free, ultra-private instant messaging with Hush Messenger
| | http://www.hushmail.com/services-messenger?l=434
| | 
| | Promote security and make money with the Hushmail Affiliate Program: 
| | http://www.hushmail.com/about-affiliate?l=427
| 
| 
| 
| 
| **********************************************************************
| This email message and accompanying data may contain information that is confidential and/or subject to legal 
privilege. If you are not the intended recipient, you are notified that any use, dissemination, distribution or copying 
of this message or data is prohibited. If you have received this email message in error, please notify us immediately 
and erase all copies of this message and attachments.
| 
| This email is for your convenience only, you should not rely on any information contained herein for contractual or 
legal purposes. You should only rely on information and/or instructions in writing and on company letterhead signed by 
authorised persons.
| **********************************************************************
|