[OWASP_PHPSEC] [Offtopic] Decrypting information out of an image

Abhishek Das das.abhshk at gmail.com
Fri Oct 4 13:46:35 UTC 2013


+1 to Maarten's method. It's visible even if you tilt your screen a bit and
see. All it needs is a bit of in-browser -webkit-filter tweaking or levels
in gimp adjustment.


On Fri, Oct 4, 2013 at 7:13 PM, Maarten Hoogveld <m.hoogveld at elevate.nl>wrote:

> I found the same thing in a different way actually. I just played around
> with the color-levels in gimp, to make the difference between white and
> almost-white (very light grey) visible. It can emphasize the contrast.
> I saw the grid clearly then, but also saw the text
> flag{youKnowWhosTheBoss} in the image itsself. (See for youself<http://imgur.com/IniFKKK>
> )
> I think that whould have been what you were supposed to find :)
> They probably left some meta data lying around :)
> Nice find!
>
>
>
> --
> Met vriendelijke groet, Kind regards,
> Maarten Hoogveld
> Elevate BV
>
>
> On Fri, Oct 4, 2013 at 2:53 PM, Minhaz A V <minhazav at gmail.com> wrote:
>
>> youKnowWhosTheBoss :)
>>
>>
>> On Fri, Oct 4, 2013 at 5:21 PM, Shivam Dixit <shivamd001 at gmail.com>wrote:
>>
>>> Hello all
>>>
>>> Thank you for your suggestions. I was able to solve the question and it
>>> was much *simpler* than I was expecting and it only required *reading
>>> meta data* and finding the value of "*flag*". I was able to scan
>>> through meta data using a tool provided on this website :
>>>
>>> http://imgops.com/
>>>
>>> The name of tool is *metapicz. *
>>>
>>>
>>>
>>> On Fri, Oct 4, 2013 at 3:26 PM, Minhaz A V <minhazav at gmail.com> wrote:
>>>
>>>> My bad just googled "stenography" and got to know Abbas and Maarten
>>>> were suggesting the same..:D
>>>>
>>>>
>>>> On Fri, Oct 4, 2013 at 3:21 PM, Maarten Hoogveld <m.hoogveld at elevate.nl
>>>> > wrote:
>>>>
>>>>> Just a tip to prevent you spending hours looking at difficult to read
>>>>> text, it's possible to solve in under 5 minutes.
>>>>>
>>>>>
>>>>> --
>>>>> Met vriendelijke groet, Kind regards,
>>>>> Maarten Hoogveld
>>>>> Elevate BV
>>>>>
>>>>>
>>>>> On Fri, Oct 4, 2013 at 11:47 AM, Minhaz A V <minhazav at gmail.com>wrote:
>>>>>
>>>>>> Shivam,
>>>>>> out of curiosity I downloaded this image from doc and opened it in
>>>>>> notepad++ and while going through its source I found something strange.
>>>>>> It had a lot of English words which included those like *Typeenum,
>>>>>> bottomOutsetlong, printOutputOptions*
>>>>>> which are not available in normal images so just have a look if this
>>>>>> can be of any help (otherwise I doubt this has something to do with
>>>>>> Photoshop).
>>>>>>
>>>>>>
>>>>>> Regards,
>>>>>> Minhaz
>>>>>>
>>>>>>
>>>>>> On Fri, Oct 4, 2013 at 2:40 PM, Maarten Hoogveld <
>>>>>> m.hoogveld at elevate.nl> wrote:
>>>>>>
>>>>>>> Hi Shivam,
>>>>>>>
>>>>>>> You could dive into converting the image in a 2-D array of intensity
>>>>>>> values and maybe even extracting the R, G and B channels separately. Then
>>>>>>> analyze that data for patterns and slight deviations which could indicate
>>>>>>> steganography of some sort.
>>>>>>> However, I would first pick the low hanging fruit and just look at
>>>>>>> the image. I see that the image is white with a very light grid. You could
>>>>>>> try to load the image in gimp <http://www.gimp.org/> or paint.net<http://www.getpaint.net/>and see if you can see something more when you zoom in so you can see
>>>>>>> individual pixels or adjust contrast, etc.
>>>>>>> Good luck!
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> Met vriendelijke groet, Kind regards,
>>>>>>> Maarten Hoogveld
>>>>>>> Elevate BV
>>>>>>>
>>>>>>>
>>>>>>> On Thu, Oct 3, 2013 at 10:08 PM, Shivam Dixit <shivamd001 at gmail.com>wrote:
>>>>>>>
>>>>>>>> Hello all
>>>>>>>>
>>>>>>>> Not much discussions on this list nowdays, so I thought of sharing
>>>>>>>> one of the questions which I came across recently in college CTF, and was
>>>>>>>> unable to solve it.
>>>>>>>>
>>>>>>>> The question is the image below :
>>>>>>>>
>>>>>>>>
>>>>>>>> https://docs.google.com/file/d/0B4G8EjUmqNchUlg1cGI3UFl4SEE/edit?usp=sharing
>>>>>>>>
>>>>>>>> (Image is white, with some grids)
>>>>>>>>
>>>>>>>> I have to decrypt some information out of it. I am not able to
>>>>>>>> think from where to start. I am *not* good at Image processing.
>>>>>>>> Please give me some suggestions on how to start ?
>>>>>>>>
>>>>>>>>
>>>>>>>> --
>>>>>>>> *Cheers,*
>>>>>>>> *Shivam*
>>>>>>>>
>>>>>>>> _______________________________________________
>>>>>>>> OWASP_PHP_Security_Project mailing list
>>>>>>>> OWASP_PHP_Security_Project at lists.owasp.org
>>>>>>>> https://lists.owasp.org/mailman/listinfo/owasp_php_security_project
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> OWASP_PHP_Security_Project mailing list
>>>>>>> OWASP_PHP_Security_Project at lists.owasp.org
>>>>>>> https://lists.owasp.org/mailman/listinfo/owasp_php_security_project
>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>>
>>> --
>>> *Cheers,*
>>> *Shivam*
>>>
>>
>>
>
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>


-- 
Abhishek Das
IIT Roorkee
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