Challenge Description: Here’s an old screenshot of chat logs between sahuang and Nathan on hollow’s Windows machine, but a crucial part of the conversation seems to be cropped out… Can you help to recover the flag from the future?
Solving Process: We’re given a zip file that contains a cropped PNG image. Around March 2023, news circulated about the “aCropalypse” - an exploit in screenshot editing tool on the Google Pixel and later discovered to exist on Windows 10 and 11 ( CVE 2023-21036 and CVE 2023-28303 )
Mindful of this, I immediately searched for any online tools that demonstrate this and came accross Acropalypse, however I had mixed success. Instead of giving a native screen resolution, I tried to give a resolution that should have been enough to reveal the rest of the sentence for the flag (the cropped screenshot dimensions were Width: 1047 Height: 246). This didn’t generate a proper image on the website, though if I downloaded the image I received an indication I was on the right track
I could see some distinct Windows elements like the taskbar, so I was confident to keep continuing in this direction and discovered an Acropalypse Restoration tool that should aid us. After getting the tool up and running, we run into the issue of the tool not running at all as the dimensions I’m trying might not be correct. Given that the width of the cropped image in 1047, what happens if we try common screen resolutions that exceed that, say 1920 x 1080?
Flag: osu{cr0pp3d_Future_Candy<3}