When a denial of service attack is detected,
mod_dosevasive will, among other things, create a
temporary file which it will use to trace actions from the
offensive IP address. This file is insecurely created in
/tmp and it's name is easily predictable.
It is then easy for an attacker to create arbitrary files
in any directory that the user under which apache runs has
privileges to write.
[...] once the target file is opened, there is a
race attack (although difficult to exploit) which can lead
to mod_dosevasive overwriting any file that the user under
which apache runs has privileges to write.