We know that images encypted with an ECB algorithm leave some traces or pattern of the original image ex..

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Original encrypted image 1

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Original encrypted image 2

Well those don’t resemble ECB encrypted images, but we are pure hearted and innocent so we decide to believe in the challenge name and description and start playing around with the images in GIMP and Stegosolve.

After some time we start seeing something:

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Image 1 with purple patterns highlighting possible characters Image 1 with black patterns highlighting possible characters

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Image 2 with different purple patterns highlighting possible characters Image 2 with black patterns highlighting possible characters

By overlapping the images and tracing over the lines we can more or less read the flag.

Overlayed and edited image revealing handwritten flag