CVE-2016-3704: Unsafe use of bash $RANDOM for NSS DB password and seed
In working on another security issue in this same script, I noticed that
Pulp's pulp-qpid-ssl-cfg script uses bash's $RANDOM in unsafe ways. One
of them is already being fixed as part of another CVE (the TMP directory
is unsafe, CVE-2016-3696), but the other two uses are:
0) The default NSS DB password is a single value from $RANDOM,
limiting it to the strings from 0 to 32768:
1) The certutil -z flag receives a "noise file". The script uses $RANDOM to
populate a file with numbers to generate this file:
Since $RANDOM is used in this way, the seed file ends up having low
diversity since only 11 possible bytes appear in the file: ASCII 0-9 and
newline. Additionally, bash's RANDOM has not been described as a
sound random generator for such purposes.
pwgen can be used to fix #0, but I'm not sure we want to depend
on pwgen. One possibility is to avoid having a default password and force
the user to provide one. Suggestions for this problem welcome.
For #1 we should just grab 8 kB from /dev/urandom and call it a day.