periodic security run output gives false positives after 1 year

[Glen Barber]

On Thu, Feb 16, 2012 at 06:59:54PM +0100, Miroslav Lachman wrote:
> Glen Barber wrote:
> > On Thu, Feb 16, 2012 at 06:04:34PM +0100, Miroslav Lachman wrote:
> >> Hi,
> >>
> >> I see it many times before, but never take a time to post about it.
> >>
> >> Scrips in /etc/periodic are grepping logs for yesterday date, but
> >> without specifying year (because some logs do not have year logged).
> >>
> >> This results in false positive alerts in security e-mails from our
> >> lightly loaded servers, where logs are not enough rotated.
> >>
> >> For example /var/log/auth.log is 62KB (838 lines) and contains entries
> >> for almost 2 years.
> >>
> >> Today I get following alert:
> >>
> >> Feb 15 22:36:03 XXX sshd[89758]: Invalid user t1na from xxx.xxx.xxx.xxx
> >> Feb 15 22:50:56 XXX sshd[89850]: Invalid user medina from xxx.xxx.xxx.xxx
> >> Feb 15 22:50:57 XXX sshd[89852]: Invalid user student from xxx.xxx.xxx.xxx
> >> Feb 15 22:50:58 XXX sshd[89854]: Invalid user student from xxx.xxx.xxx.xxx
> >>
> >> (hostname and IP are replaced by X)
> >>
> >> But looking in to auth.log I found zero entries from yesterday - Feb 15
> >> entries were logged 1 year ago!
> >>
> >> So I propose to set all daemons / syslog to log year too (as %Y) and
> >> change  yesterday=`date -v-1d "+%b %e "`  to yesterday=`date -v-1d "+%b
> >> %e %Y"` in periodic scripts.
> >>
> >> The affected scripts are:
> >> 460.status-mail-rejects
> >> 470.status-named
> >> 800.loginfail
> >> 900.tcpwrap
> >>
> >> Maybe some others, I did just a quick grep -rsn 'date -v-1d'
> >> /etc/periodic and I don't know the logic used in other script to get
> >> yesterday messages.
> >>
> >> What do you think about it?
> >>
> >
> > Rotating the appropriate logs daily/weekly/monthly/whatever will silence
> > these false alarms.
> 
> My post was not about "how can I fix it localy", but what sould be done 
> in FreeBSD distribuition, because these false alerts were made by 
> default FreeBSD configuration (coincidence of newsyslog settings, 
> periodic scripts and log format)
> 

IMHO, this isn't something the FreeBSD installation can "guess" as a
suitable default, but up to the administrator to define what is
appropriate for their system.

Glen