Editing WoW:API random (section)

=== On random number generator distribution and security ===
The ANSI C rand() function is a Linear Congruential Pseudo-Random Number Generator (LPCRNG). Statistically speaking, LCPRNGs have a fair distribution. However, from a security standpoint they are very weak.

If you depend on random numbers to keep something secret or someone out of something, they only need to see a handful of numbers to be able to guess the next one accurately. In fact, if you output large enough numbers, they only need to see a single number to determine the next one. This is the standard LCPRNG used by Microsoft (written in C):

  rng = rng * 214013 + 2531011
  return (rng>>16)&0x7fff;