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There is a flaw present now in the Windows 11 Snipping Tool and Windows 10 Snip & Sketch tool, which keeps the parts of the images you cropped instead of completely removing them. If the same file is accessed by the wrong hands, this could mean trouble to users, especially those who frequently use these tools to crop sensitive and confidential photos, such as credit cards, explicit images, documents, and more.
I've got a fun one for you all to look at.
I opened a 198 byte PNG with Microsoft's Snipping Tool, chose "Save As" to overwrite a different PNG file (no editing), and saves a 4,762 byte file with all that extra after the PNG IEND chunk.
Sounds similar 😀
— Chris Blume (@ProgramMax) March 21, 2023
Called the “acropalypse,” the flaw can be used to recover “cropped” parts of photos that are seemingly removed during the cropping process. This was first spotted in Google Pixel’s Markup Tool by experts, who demonstrated it via an acropalypse screenshot recovery utility. Now, the same flaw is reportedly affecting Windows 11 Snipping Tool and Windows 10 Snip & Sketch tool. Microsoft, however, still hasn’t made any clarifications about the issue.
Different experts, including Will Dormann (who also discovered the ASLR flaw and a zero-day flaw in the Windows Mark of the Web labels) and David Buchanan (who found the acropalypse in Google Pixel), confirmed the issue after showing proof. Bleeping Computer also performed this and provided a good technical explanation documenting this issue. According to the report and as mentioned by another expert and software programmer, Chris Blume, Snipping Tool saves cropped files “with all that extra after the PNG IEND chunk,” meaning it preserves the data instead of ignoring them.
In recent posts, Dormann showed how Snipping Tool retained the file size of the images despite undergoing the cropping process.
“When saving over a file, Snipping Tool will overwrite the number of bytes required to save your edited image, leaving the remaining bytes intact,” explains Dormann, who later showed that a complete step-by-step guide on how to recover the cropped image parts using jpg.repair.
On a slightly positive note, not all PNG files are covered by this problem, and the acropalypse screenshot recovery app is reportedly not working on Windows files at this time. However, a Python script can be used as another option, as Bleeping Computer proved.