Sunday 7 August 2011

ZIP bomb

A zip bomb, also known as a Zip of Death, is a malicious archive file designed to crash or render useless the program or system reading it. It is often used by virus writersto disable antivirus software, so that a more traditional virus sent afterwards could get into system undetected. A zip bomb is usually a small file (up to a few hundred kilobytes) for ease of transport and to avoid suspicion. However, when the file is unpacked its contents are more than the system can handle.You can make your own zip bomb to annoy your friends or just out of curiosity (or wilderness) to experiment with it. Make sure you don't detonate it on yourself.



Here is how to make your own Zip of Death -

Create a new text file,name it a.txt



Open and type the null character (alt + 255) in it.
Now press Ctrl + A then Ctrl + V a couple times to make some null bytes.If u have a hex editor,then make the hex 00 for about 50 kilobytes.
Now make several copies of a.txt in the same directory and name them accordingly.


Open Command prompt and navigate to the folder containing a.txt . Type -
copy /b *.txt b.txt


This will write all the contents of a.text and its copies into a new text file called b.txt,hence making every copy is a super copy. Repeat the above steps from the beginning again and again to make a really big text file.
Once u have a nice empty big text file like 1gb or more,then compress it using Winrar or Winzip into a zip file.
You will find that it will be compressed to very small size (about 1MB ). It is because of the simple construction of the file as the text file contains 1gb of null bytes.
For added fun,open the compressed zip file file into a hex editor. You will see a bunch of hex 5555.Just add some more and the file will expand amazingly.


Make sure that YOU DONT OPEN THIS afterwards.
You can make the same file in Linux by typing -
dd if=/dev/zero bs=1000 count=1000000 | gzip > test.gz
Send it to your friends (or foes) and it will definitely annoy them . Use some creativity and rename the text file into some thing like Angelina Jolie.jpg and compress it and email to your friends. Once they download it,they will never be able to download again (sarcasm..sarcasm).More disastrous combinations can be made by experimenting with it.I mean..you get the idea :)
Also,you can check out the one of the most famous zip bombs alive today – 42.zip (only 42 KB) which will uncompress to about 4 Petabytes (1 Peta byte = 1024 TB and 1 TB = 1024 GB ) of file size. Dangerous huh..?

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