[parfe]

>* Block ciphers in the default mode ("ECB").

You can plainly see the problem ECB causes in this example image: http://legacy.kingston.com/secure/image_files/Figure2_ECB.jp...

[tptacek]

This is a perennial favorite illustration of "what's wrong with the default mode", but it's biggest problem is that given chosen plaintext, you can often decrypt it a byte-at-a-time.