RE: Should webservers, eg. IIS 6 have anti--virus installed on them?

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Date: Tue, 19 Jul 2005 14:54:58 -0700
To: "Harlan Carvey" <keydet89@yahoo.com>, <focus-ms@securityfocus.com>

CIL...

Jim Harrison
Security Business Unit (ISA SE)
"When you come to a fork in the road, take it."

--Yogi Berra

-----Original Message-----
From: Harlan Carvey [mailto:keydet89@yahoo.com]
Sent: Tuesday, July 19, 2005 8:11 AM
To: focus-ms@securityfocus.com
Cc: jeff@shawgo.com
Subject: RE: Should webservers, eg. IIS 6 have anti--virus installed on
them?

So far, this is has been an interesting discussion,
but beneath it all, I'm seeing what I think is a
disturbing trend.

> Antivirus needs to be part of the overall security
> plan for all Windows machines - it's just part of
> the cost of doing business - the cost of the
> software, maintenance, and CPU overhead.

I'm seeing absolutist statements like the one above,
and it bothers me.

If a web server is just a web server, the content is
served to the client, going outbound...not coming into
the server. If the purpose of the system is to take
known-good pages (from the owner) and make them
available to the public (over ports 80 and 443), then
what is the point of A/V software?

[Jim] - Web servers are no longer "text-spewing machines" that merely
hand out static content. They're dynamic applications that can be (have
been) subject to attack and infection from outside. It's only a matter
of time before someone realizes how to misuse one feature or another to
make the web server do something entirely unintended by its owners. AV
software that scans incoming files can help here.

I'm seeing a lot of people say that A/V software is
necessary, and that it's part of a 'holistic' or
'defense in depth' approach, but this really sounds
more like Dilbert's "buzz word bingo" than anything
else.

[Jim] - There are things that "just make good sense" to the majority of
folks, but ultimately, it's your choice. If you feel the lockdown
processes are sufficient, then that's your risk to take.
 
> Certainly, servers need to be patched, firewalled,
> isolated, and locked down. Additionally, code
> should be audited for vulnerability to XSS and SQL
> injection.

Yes, without a doubt. This is all part of good
administration.

> None of these things are perfect. Not that AV is
> perfect, but it is another layer of defense - making
> it part of that "Defense in Depth" strategy.

But, defense against what?

> AV has grown into more than just defense against
> viruses. It is often effective against worm code,
> and some AV has identified common hacking tools
> (e.g. - NetCat) as something that doesn't belong on
> most systems. You can argue the viability of this
> move, but most companies - if they have a security
> team - have less that 0.1% of their machines which
> maybe should have it there.

"something that doesn't belong on most systems"? How
does it get there? If a web server is properly
configured and managed, then perhaps the most likely
means of infection is from the administrator
himself...and in such cases, A/V software is useless.

[Jim] - not entirely true - just because the admin infected the machine,
doesn't mean he intended to. Also, you can't assume that every
infection is "new". Blaster, Slammer, Nimda and a screaming plethora of
other "old" baddies are still wandering loose on the 'Net looking for a
victim.

 
> AV needs to be part of the cost of running Windows -
> for better or for worse.

Again, I'm seeing this as an approach that's being
parrotted, rather than thought out. I'm not saying
that MS products are perfect...not at all. But what I
am saying is that using proper administration
principles, those that have been espoused for well
beyond the past decade, paying additional money to add
yet another software package to a web server simply
doesn't make good business sense.

Why pay more money for another application to
maintain, and another set of logs that you're not
reviewing anyway?

Several years ago, Dave LeBlanc set up an IIS 4.0
server in accordance with simple common sense, and it
was not vulnerable to Code Red...a full year before
Code Red was launched.

When Code Red was launched, A/V software would not
have helped. However, if the .hta script mapping had
been disabled the day before Code Red came out, then
guess what? No problems.

Should systems have A/V software in place?
Maybe...depending upon the function and purpose of the
system. Does it make sense? Does it make good
business sense? What's the business
reason/justification for installing another software
package (for $$) over disabling current functionality
(which doesn't cost anything)?

Harlan

------------------------------------------
Harlan Carvey, CISSP
"Windows Forensics and Incident Recovery"
http://www.windows-ir.com
http://windowsir.blogspot.com
------------------------------------------

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• Previous message: Harlan Carvey: "RE: Should webservers, eg. IIS 6 have anti--virus installed on them?"
• Maybe in reply to: Sarbjit Singh Gill: "Should webservers, eg. IIS 6 have anti--virus installed on them?"
• Next in thread: Brady McClenon: "RE: Should webservers, eg. IIS 6 have anti--virus installed on them?"
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