I agree with Debasis.
I spent a year and a half in an Infosec Office doing code audits for
E-Commerce web apps. I tried various open source automated tools and found
that most of them missed the vast majority of exploitable vulnerabilities.
In my experience, nothing beats a line-by-line analysis of the code by
someone who knows what to look for. Yes, it's time consuming and completely
impractical for sufficiently large applications, but it's more effective
than the tools I tried out.
As for estimating time requirements for line-by-line analysis, I've always
been a fan of "under promising and over delivering," and found I could bid
successfully at about a minute per line of code, from there calculate your
hourly rate accordingly.
I wish I could have tried out some commercial tools, but we were too cheap
for that.
When dealing with web apps, walk through the application, note all user
inputs and even those useless "hidden" fields that so many web app
developers are fond of using, trace through the code and verify that the
developer is validating and sanitizing those inputs correctly. If you want
to be really anal (we are talking security here right?), then you should
also verify that database inputs are also validated and sanitized and
outputs sent back to the user. When you're dealing with E-Commerce apps,
it's hard to be too paranoid.
For web app testing, proxies like Web Scarab from OWASP are invaluable.
Haven't tried Paros but it sounds excellent.
Cheers.
On 6/27/07, Debasis Mohanty <debasis.mohanty.listmails@gmail.com> wrote:
8< snip >8
Though this is an important phase during code review but definitely
not an ultimate phase to find security holes. The important phase is
what comes next i.e. Manual Data Flow (DF) and Control Flow (CF)
analysis.
d) Manual Data Flow (DF) and Control Flow (CF) analysis
DF analysis - http://en.wikipedia.org/wiki/Data_flow_analysis
CF analysis - http://en.wikipedia.org/wiki/Control_flow_graph
Performing both DF and CF analysis manually takes lot of time but is
definitely most important part of code review. It helps identifying
accurate threats from security standpoint. This phase requires a
master code security ninja's hand to ensure actual issues are
captured.
--
ireadit@gmail.com
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