Excluding audit for BIND daemon

Sat Sep 23 18:16:35 UTC 2017

On Saturday, September 23, 2017 10:08:40 AM EDT Rituraj Buddhisagar wrote:
> Continued...from previous mail of mine..
> 
> While I am reading and exploring much on auditd & on how I can have a
> proper central system where logs are stored and daily reports get
> generated, you might want to look at my config file on server and
> suggest/recommend if anything - would appreciate if any pointers.
> 
> I am using default config which came with Ubuntu 16.04 and only change was*
> "-F auid!=4294967295"* on line where root_action is defined .

There is no rule, root_action, that is shipped with the audit package. I would 
be interested in seeing it if you could copy and paste it into a reply.

-Steve

> On Sat, Sep 23, 2017 at 7:30 PM, Rituraj Buddhisagar <rituraj at vayana.com>
> 
> wrote:
> > Hi Steve,
> > 
> > Thanks for the response.
> > 
> > Suppressing the events with -F auid!=4294967295 worked.
> > 
> > I am seeing the events like "vi" "chmod" etc are getting audited by the
> > system - even as a root account.
> > 
> > I am yet to understand fully though on various rule sets and also on
> > components like audisp / audisp-remote. So reading more ..
> > 
> > 
> > Best Regards,
> > Rituraj B
> > 
> > On Fri, Sep 22, 2017 at 10:17 PM, Steve Grubb <sgrubb at redhat.com> wrote:
> >> Hello,
> >> 
> >> On Friday, September 22, 2017 1:09:19 AM EDT Rituraj Buddhisagar wrote:
> >> > I have a DNS server for which the auditd was generating lot of system
> >> 
> >> calls
> >> 
> >> > and flooding the logs.
> >> > Due to this  the server was under heavy memory usage as audisp-remote
> >> 
> >> was
> >> 
> >> > hogging the memory.  The log output for audisp-remote showed that the
> >> > syscall was 49. Then I got to know from ausyscall command that the call
> >> > number 49 corresponds to bind. Hence I have *excluded* the call to
> >> 
> >> "bind".
> >> 
> >> > I have put in below line in the /etc/audit/audit.rules
> >> > 
> >> > *-a exclude,always -S 49*
> >> > 
> >> > I have put the above line before section 10.2.2 which says "Feel free
> >> > to
> >> > add below this line" (please note I am running Ubuntu 14.04 but I
> >> 
> >> suppose
> >> 
> >> > auditd implementation is same across board) .
> >> 
> >> Also know that the rules are looked at from top to bottom with the first
> >> match
> >> winning. So, you would want this rule above whatever is causing events.
> >> 
> >> > After the exclusion - I no more see the syscall=49 line in
> >> > /var/log/audit/audit.rules. So thats a success of sorts!
> >> > 
> >> > *Probem/Issue/Query now*: After the exclusion, I do see audit events
> >> > for
> >> > cron , sudo etc. But I do not see a call for "vi" file open mode etc.
> >> 
> >> I'd need to see the rules to figure out what's wrong, but I have some
> >> hints
> >> below...
> >> 
> >> > *Background:*
> >> > 
> >> > log output earlier which was flooding the logs and giving message "
> >> 
> >> *dns1
> >> 
> >> > audisp-remote: message repeated 6613 times: [ queue is full - dropping
> >> > event"*
> >> > 
> >> > *log:*
> >> > *type=SYSCALL msg=audit(1506025977.586:46629194): arch=c000003e
> >> 
> >> syscall=49
> >> 
> >> > success=yes exit=0 a0=3 a1=7ffe540ecf20 a2=c a3=0 items=0 ppid=22337
> >> > pid=22338 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0
> >> 
> >> sgid=0
> >> 
> >> > fsgid=0 tty=(none) ses=4294967295 comm="audisp-remote"
> >> > exe="/sbin/audisp-remote" key="root_action"*
> >> 
> >> The main question is what is the root_action rule(s)? Normally we add a
> >> auid!=4294967295 to prevent daemons from causing events. Typically when
> >> it's
> >> desired to get root events, its means that you want to target _people_
> >> running
> >> as root rather than normal system activity.
> >> 
> >> > root at dns1:/tmp# ausyscall 49
> >> > *bind*
> >> > 
> >> > I do see audit events for cron , sudo etc. But I do not see a call for
> >> 
> >> "vi"
> >> 
> >> > file open mode etc.
> >> > 
> >> > Observation: I open file /etc/audit/audit.rules in vi editor and then
> >> 
> >> close
> >> 
> >> > it. Audit log does not show syscall=2
> >> 
> >> If you were wanting to record writes to that, you would use a rule like
> >> this:
> >> 
> >> -w /etc/audit/ -p wa
> >> 
> >> > Earlier I used to see below output in logs, but I am not sure that was
> >> 
> >> for
> >> 
> >> > which file opened in vi editor.
> >> > 
> >> > *type=SYSCALL msg=audit(1506025995.825:46633170): arch=c000003e
> >> 
> >> syscall=2
> >> 
> >> > success=yes exit=3 a0=5598f609a210 a1=200c1 a2=81a0 a3=0 items=2
> >> 
> >> ppid=21957
> >> 
> >> > pid=22355 auid=1006 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0
> >> 
> >> fsgid=0
> >> 
> >> > tty=pts0 ses=361 comm="vi" exe="/usr/bin/vim.basic" key="root_action"*
> >> 
> >> Typically, its expected to look at events through ausearch. It groups the
> >> records into events. You can also use aureport to see summary
> >> information.
> >> 
> >> > I did read a bit on auditd from below links. *Please let me know if I
> >> > am
> >> > missing something or are the calls getting audited in an expected way.*
> >> > 
> >> > 
> >> > I went through below links; *would appreciate if someone can help with
> >> 
> >> any
> >> 
> >> > references which are more lucid with example*s:
> >> > 
> >> > https://linux-audit.com/configuring-and-auditing-linux-> >> 
> >> systems-with-audit-da
> >> 
> >> > emon/
> >> 
> >> I was not aware of that site. But some of the information appears to be
> >> dated.
> >> For example, telling people to use pam_tally2 when they should be using
> >> pam_faillock.
> >> 
> >> > https://access.redhat.com/documentation/en-US/Red_Hat_Enterp
> >> 
> >> rise_Linux/6/ht
> >> 
> >> > ml/Security_Guide/chap-system_auditing.html
> >> > 
> >> > Furthermore, I would like to read much on audisp-remote to send all
> >> 
> >> these
> >> 
> >> > logs to a central server. I do not find any documentation on that. I
> >> > see
> >> > discussion on net where people are using rsyslog instead for that.
> >> 
> >> Please
> >> 
> >> > help with references/links if any.
> >> 
> >> Admittedly there is not much written. It is on my list of topics to blog
> >> about. But I haven't had time for blogging lately.
> >> 
> >> -Steve