The concept of a zip bomb is nothing new. Beyond its classic malicious intent, zip bombs are notable examples of extreme compression, but they generally rely on recursion to escape the natural limits of the Deflate algorithm. However, researcher David Fifield created a variant of the old 42.zip bomb that doesn't use recursion, meaning it expands completely after a single round of decompression. The final size is 4.5 petabytes... something like 30 billion Facebook photos.
If you try to detonate a zip bomb today, the antivirus of the moment will most likely intercept that process and report its activity as malicious, or the browser will block its download. Basically, the idea is that by accumulating multiple layers of zip files filled with information with a high level of compression, we can escape the limits of the algorithm used. In the case of Deflate, adopted by a wide number of ZIP parsers, its compression rate cannot go beyond 1032:1.
A Zip Bomb Without Recursion
That's when recursion comes into play. In essence, with each new layer you acquire another round of 1032:1, a technique that gave rise to things like 42.zip, a file that has a standard size of 42 kilobytes, but spits out 4.5 petabytes of data. Now, what if someone designed a similar file, discarding the recursive component? Well... the truth is that such a file already exists. Its creator is researcher David Fifield, and he explains the complete process on his official page.
How the Technique Works
The method is based on an overlay of files within the zip container, creating references to a highly compressed "core" of information, but without creating multiple copies of it. The size of the bomb grows quadratically, meaning the larger the bomb, the better the compression rate. Some of its demos include a 42-kilobyte file that expands to 5.5 gigabytes, and another 10-megabyte file that jumps to a chilling 281 terabytes.
Testing the Bomb
The final result required the Zip64 extension to escape the upper limit of 281 terabytes, which makes it lose a bit of compatibility. However, when we try to download it with Chrome, its analysis never seems to end, showing 100 percent disk activity. If you want to try it, the link is below. Only... be careful.
Official website: Click here
