OSSEC integrity checksum alert - what caused the change?

Two reasons are:

  • You've actually been hacked
  • Prelinking is enabled

You can disable prelinking by editing /etc/sysconfig/prelink from:

PRELINKING=yes

to:

PRELINKING=no

And running:

prelink -ua

Source: http://www.ossec.net/wiki/Know_How:Check_Sums