Sup Forums embedding botnet into images

So recently a guy uploaded an image of the Alexander Mosaic on /his/ which had a file size 3.62MB. The image is from the Wikipedia commons. When downloading the image off Sup Forums, a user found that its file size actually increased to 4.27MB, despite it being listed as 3.62MB on the website, and 4MB being the website's file size limit. I tested it myself and also got the same results, with the image's file size increasing to 4.27MB when being downloaded off Sup Forums. The image obviously cannot be re-uploaded to Sup Forums due to the file size limit.

I have uploaded the original Wikipedia commons image here, so that you can test if the file size increases to 4.27MB when downloading it. If not, try downloading it off the original thread found here .

What is the explanation for this Sup Forums? Sup Forums reportedly does not apparently tamper with the images uploaded to its servers, and it's especially odd that the image's file size actually increases rather than decreases (some websites like Imgur compress their images). The file size here actually exceeds the upload limit. I'm not saying it's necessarily anything malicious, but for curiosity's sake I would like to see if anyone here has an explanation for this. If no explanation can be made, Sup Forums is presumed to be guilty.

Other urls found in this thread:

commons.wikimedia.org/wiki/File:Battle_of_Issus.jpg
my.mixtape.moe/celdxt.jpg
twitter.com/SFWRedditVideos

Here is a comparison screenshot of the properties of both images. On the right is the original image downloaded off Wikipedia, and on the left is the tampered image downloaded off Sup Forums.

>Bigger file created before the smaller one

I'm thinking there is some junk in the metadata that is taking up all the space and not counted in image file size by Sup Forums.

When you strip all the metadata the file returns to the 3.7MB size.

I downloaded the Wikipedia original a minute after the Sup Forums one, Goofy. That means nothing.

It's here by the way:
commons.wikimedia.org/wiki/File:Battle_of_Issus.jpg

>Sup Forums reportedly does not apparently tamper with the images uploaded to its servers, [...]
Before we go full retard here, I'll just point out that this is a false premise.

Even back when moot owned the joint, they started stripping metadata as /soc/ was becoming more popular, maybe five-seven years ago.

I remember that in particular, because I used to hide messages in there. Like upload a selfie of myself to /k/ bragging about having illegal guns or whatever, with the location set to FBI headquarters.

>I DONT UNDERSTAND COMPRESSION THE POST

I tried deleting all the metadata, it remained the same. Try it yourself.

Also an extra 650kb for simple metadata seems like a lot.

wait, god damn it. are you telling me I've been stripping metadata all these years for no reason and never bothered to check?

Do you? Sup Forums does not recompress its images, so they should stay exactly the same in file size. The "Properties.jpg" image I just downloaded stayed at 151KB, which is what I uploaded it at. The Alexander Mosaic image increases in size by over 600kb. That's not normal.

I once remember a kid that got doxxed because he posted a photo of his retarded video on Sup Forums without stripping the EXIF data.

Was that the kid who anons kept calling and his dad started going ballistic and made a whole series of decade+ lasting memes? I also remember some news special being done on a kid being harassed. Although if I remember correctly in one of the threads anons found out where he lived by matching the trees in his front yard to google maps streetview

Why the fuck do people even post this shit on the internet anyways?

>Why the fuck do people even post this shit on the internet anyways?
they're retards who want attention and don't even stop to think about possible consequences if they fuck up

Use something that strips the metadata, like imagemagick.

Mind you even after that the file is still 90,000 bytes larger than the original.

steganography?

I'd do a few tests first, just in case it's just a board-specific thing, or in case it's changed.

sounds like it. don't know how to test though.

Open in notepad and as archive

trying something out

>"(3.9 MB, 4000x3000)"
>download it
>it's 3.5MB
neat

second try

last one

bump for importace

test

For each pixel, subtract the rgb values of the larger image from the rgb values of the smaller image and look for the difference.

Creepy.

I get this weird Chinese shit coming up in hidden files on my desktop after downloading any image off Sup Forums to my desktop

How do you reason that an image can run a malicious script without being copied into notepad and saved as javascript or something?

Don't forget the picture of pipe-bombs with the bomb threat kid and the Burger King feet-in-lettuce kid.

Exploiting errors in image rendering software.

>What is the explanation for this Sup Forums?

you downloaded the image to your phone, which is using FAT32 as a filesystem, and is really inefficient. it often uses more blocks to store a file than NTFS.

Did pixel-by-pixel difference in photoshop, pictures are completely identical despite the difference in file size.

Please off yourself.

I once had '.owls nest' as an invisible folder on my desktop when I had an owl as a desktop wallpaper

el capitan, tons of pirated software because fuck the jews that are ruining applel right now

didn't care for months, but felt stupid

dem hackers be hackin'

If you're trying to refer to file cluster size then you are way off the mark.

>reddit spacing

The Wikipedia image uses progressive DCT, the Sup Forums one doesn't. So doing another round of compression ended up increasing its file size since the jpeg encoder needs to factor in the jpeg artifacts already present.
Let me test this theory. This image should have a different file size than this one:
my.mixtape.moe/celdxt.jpg

Mystery solved. You're welcome.

You seem to be on to something.

Yeah, the images on Sup Forums are definitely being transcoded as I did a check between the original and the trimmed downloaded and there don't seem to be identical blocks in the hex.

Probably when it goes through the processing to strip the exif the output is limited to a certain format so it gets transcoded.

fuck you for making me save lolishit to test this

You could have just used the picture that, you know, the thread is about. Or upload your own. Lmao @ you feigning reluctance to engage in your pedofaggotry.