And if Tomas shares his code, that would be nice too :D

On Mon, Jul 15, 2013 at 11:49 AM, Dominique Righetto
<dominique.righe...@gmail.com> wrote:
> Hi,
>
> Thanks you. I will use your feedback to understand and find the
> vulnerability detection methods.
>
> Best regards,
> Dom
>
> --
> Cordialement, Best regards,
> Dominique Righetto
> dominique.righe...@gmail.com
> dominique.righe...@owasp.org
> Twitter: @righettod
> GPG: 0x323D19BA
> http://www.righettod.eu
> "No trees were killed to send this message, but a large number of electrons
> were terribly inconvenienced."
>
>
> On Mon, Jul 15, 2013 at 1:54 PM, Andres Riancho <andres.rian...@gmail.com>
> wrote:
>>
>> On Sun, Jul 14, 2013 at 4:49 AM, Dominique RIGHETTO
>> <dominique.righe...@gmail.com> wrote:
>> > Hi Tomas,
>> >
>> > Thanks you very much.
>> >
>> > I try to understand the objective of each of the value in
>> > ["-0000012345", "-2147483649", "-2147483648", "0000012345",
>> > "2147483647",
>> > "2147483648", "4294967295", "4294967296", "0000023456"].
>> >
>> > For values: 2147483647,2147483648,-2147483649,-2147483648
>> > I understand because it's a for testing around the limits of the Integer
>> > type but for other values I dont understand why they are used and from
>> > where
>> > they come from ?
>>
>> The most important part seems to be here [0]
>>
>> [0]
>> https://code.google.com/p/skipfish/source/browse/trunk/src/checks.c#1872
>>
>> > As I understand the vulnerability, according the all the stuff that I
>> > can
>> > read, is the fact below:
>> >
>> > A parameter has a Integer overflow vuln if, in the case in which you
>> > submit
>> > a value over the max/min limit of the Integer, it return a very small
>> > negative or positive value.
>> >
>> > Ex:
>> > You submit "2147483648" and the returned value is negative
>> > You submit "-2147483648" and the returned value is positive
>> >
>> > Can you confirm to me that's my understanding is correct ?
>>
>> I'm no good with these low level bugs, but my basic understanding of
>> the vuln makes me think that the best way to detect this vuln is:
>>     * Send HTTP request with a test payload, lets say... 5 , save it
>>     * Send HTTP request with a test for integer overflow, which if
>> successful would be the same as sending the number 5, (calculate that,
>> but it should be -(2^31-5) or something like that), save it
>>     * Compare the two. If they are equal we're in a case where integer
>> overflow is present OR the input is not even used
>>     * Send one more HTTP request with a number 8 (different from the
>> previous), compare with any of the previous ones. If it's different
>> then integer overflow is present.
>>
>> If you want to have lower false positives, after running through those
>> steps you could run one more test round, repeating step 1 and 2 with a
>> number different than 5.
>>
>> @Thomas: is this how you were doing it?
>>
>> > I apologize for all my questions but I really want to fully understand
>> > the
>> > context of the vulnerability in order to take in account all the cases
>> > into
>> > the plugin implementation and also learn new things.
>> >
>> > W3AF team is a very cool learning environment, I feel like a dwarf among
>> > giants ;o)))))
>> >
>> > Thanks in advance.
>> >
>> > Best regards,
>> >
>> > Dom
>> >
>> >
>> >
>> > On 13/07/2013 15:48, Tomas Velazquez wrote:
>> >>
>> >> Hi Dominique,
>> >>
>> >> Months ago I code a poc of integer overflow, but it is unfinished.
>> >>
>> >> My code is based on skipfish detection:
>> >> http://code.google.com/p/skipfish/source/browse/trunk/src/checks.c
>> >>
>> >> Regards,
>> >>
>> >>
>> >>
>> >> On Sat, Jul 13, 2013 at 10:09 AM, Dominique Righetto
>> >> <dominique.righe...@gmail.com <mailto:dominique.righe...@gmail.com>>
>> >> wrote:
>> >>
>> >>     Hi Andres,
>> >>
>> >>     I'm working on integer overflow detection plugin and I try to
>> >>     understand, in a audit plugin, how to access to injection points
>> >>     detected by in discovery part.
>> >>
>> >>     Can you give me some pointer or plugin example ?
>> >>
>> >>     Thanks in advance
>> >>
>> >>     Dom
>> >>
>> >>
>> >>
>> >> ------------------------------------------------------------------------------
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>> >>
>> >>
>> >
>>
>>
>>
>> --
>> Andrés Riancho
>> Project Leader at w3af - http://w3af.org/
>> Web Application Attack and Audit Framework
>> Twitter: @w3af
>> GPG: 0x93C344F3
>
>



-- 
Andrés Riancho
Project Leader at w3af - http://w3af.org/
Web Application Attack and Audit Framework
Twitter: @w3af
GPG: 0x93C344F3

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