RE: Suppress messages from /var/log/audit.log via audit.rules

Worsham, Michael
2011-11-03T17:06:52Z

After contacting DISA today, here is what they responded with:

"The SRR script currently does not support RHEL 5, only 3 and 4. Also, the STIG for RHEL 5 is currently in draft form and a manual review would need to be performed on the assets: http://iase.disa.mil/stigs/os/unix/red_hat.html"

So I took a look at the RHEL 5 draft and found this entry:

Group ID (Vulid): V-814
Group Title: Audit failed file and program access attempts
Rule ID: SV-27291r1_rule
Severity: CAT II
Rule Version (STIG-ID): GEN002720
Rule Title: The audit system must be configured to audit failed attempts to access files and programs.

Vulnerability Discussion: If the system is not configured to audit certain activities and write them to an audit log, it is more difficult to detect and track system compromises and damages incurred during a system compromise.

Responsibility: System Administrator
IAControls: ECAR-1, ECAR-2, ECAR-3

Check Content:
Check that auditd is configured to audit failed file access attempts.

# cat /etc/audit.rules /etc/audit/audit.rules | grep -e "-a always,exit" | grep -i "open"
If no results are returned, or the results do not contain "-S open" and "-F success=0", this is a finding.

Fix Text: Edit the audit.rules file and add the following line to enable auditing of failed attempts to access files and programs:
-a always,exit -F arch=<ARCH> -S open -F success=0 Restart the auditd service.

The 'Fix Text' sounds like it will still spam the audit.log or am I missing something?

-- Michael

-----Original Message-----
From: Steve Grubb [mailto:sgrubb@redhat.com]
Sent: Wednesday, November 02, 2011 1:12 PM
To: Worsham, Michael
Cc: linux-audit@redhat.com
Subject: Re: Suppress messages from /var/log/audit.log via audit.rules

On Tuesday, November 01, 2011 11:45:51 AM Worsham, Michael wrote:
> SRR still shows this as a failure, using stig.rules contents for
> audit.rules:
>
> GEN002720: UNIX STIG: 3.16 - The audit system is not configured to audit
> failed attempts to access files and programs. AUDITING is NOT correctly
> CONFIGURED on va33-time.
> Ensure that -a exit,always -S open -F success=0 is in /etc/audit/audit.rules

This ^^^ is wrong. For example, it does not limit the syscall by the arch. So what
this means is that it will look up the open syscall for the arch that auditctl is. So,
lets see what that does:

# ausyscall open
open 2

OK, now what does the 32 bit API think of it?
# ausyscall 2 i386
fork

So, that rule will watch for all 32 bit forks and 64 bit opens. Is that what your
security folks want?

Additionally, the intent of the STIG is to catch failed opens due to permission
problems. You are going to trap normal system activity when glibc goes looking around
for library resolution information. This will waste space in your logs and make it
hard to find actual problems.

> PDI Number: GEN002720
> Finding Category: CAT II
> Reference: UNIX STIG: 3.16
> Description: The audit system is not configured to audit failed attempts to
> access files and programs. Status: Open
>
>
> Is there any documentation that says that the stig.rules file is compliant
> for GEN002720?

There are no docs that I know of. I could write one, but would that be authoritative?
:)

> The project security folks will only be looking at the SRR
> output, which says it's not.

And the SRR is completely wrong. So, they need to have some understanding that you
either want a system configured right but failing the SRR's or matching the SRR's but
configured wrong. I'd hate to be in your position, but that's where you are.

> We are using the rules as found here:
> https://fedorahosted.org/audit/browser/trunk/contrib/stig.rules

These rules are correct. You can contact DISA to verify.

-Steve

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