Re: ForeScout ActiveScout

[Gadi Evron <ge () linuxbox org>]

Brent Stackhouse wrote:
> Hello,

Hi.

I tested ActiveScout, so I'd like to respond. Before hand, allow me to 
say that although I've used different IDS/IPS products extensively, and 
tested many of them (companies always want to test them on our network, 
being, according to comparisons I made so please don't take my word for 
it, one of the most attacked networks in the world).

I am by no way close to being an IDS/IPS expert nor was I ever involved 
in development of such, save for writing signatures and a good 
understanding of theory.

> Just a quick question on ForeScout ActiveScout as to
> whether anyone out there has used/eval'd it.  I'm
> working with a client that is using an old version
> (2.7.x, I believe), is considering an upgrade, and I'm
> not sure it's worth the time and effort.

The upgrade is extremely easy and quick (or should be, and was for me). 
Cost vs. benefit. I don't see why not. Go for it, there are improvements.

> They claim 100% accuracy which we all know is silly. 

Usually, I'd be the first to agree. Still, in this case, they claim 
right. How come?

Basically, as far as I understand it, they say: "we wait for you to 
check us out, and then we watch you. If you come back and try something 
evil, we will know it is you and that you are trying it".

Now, I still don't like "100%" claims regardless, but under this 
definition, they are right. They don't catch 100% of all attacks, but it 
is "virtually impossible" for them to make a false positive if all 
things are even (no bug or weird network issues), and things are usually 
even.

In my personal experience, false positives COULD rarely occur with weird 
network issues (and that's not their fault), but in my experience 
ActiveScout will then MONITOR an IP it shouldn't, but it wouldn't block 
it. What's the harm in that?

> Their whole methodology is based on an attacker using
> recon in advance of an attack and that the recon
> activity is detectable enough to start interfering
> with it.

Yep.

> > From what I can gather from ForeScout's literature and
> the management console of the app itself, when it's
> able to run at all (Java-based, slow as dirt), this

It works fine for me. Maybe your machine is slow as dirt.

I do agree it has a rather old look. I personally really dislike it, but 
it's just a GUI.

> product sits on the outside of the perimeter and looks
> for suspicious traffic via a span session.  When it
> detects scans or similar recon activity, it can both
> send back spurious information to the source IP and
> update a firewall to block it.  It seems to track
> attacking IP's based on the spurious info it already
> fed them.

It's really an incredible concept (if we leave the product aside for a 
second). They feed the probing (not attacking) user false data. If that 
IP returns, it is a bad guy. If another one returns with the false data 
- it is the same guy, and he is obviously evil. Thresholds can be set, 
nobody said that if you went to port 445 instead of 443 twice, you'd 
trigger it. Very configurable. Plus, if I remember correctly, there are 
thresholds for preventing it from getting DDoS'd as well.

As to blocking - you don't have to let it use the FW. It can send resets.

They have a pretty neat (yet old looking) picture of the world, too. It 
really helps out with the budget people.

> Also, this version doesn't seem to track SMTP and DNS,
> two of the most oft-attacked protocols out there.

Why should it? It is not a regular IDS or IPS and in no way comes to 
replace them. If it sees a bad user doing something that would demand 
him being "marked" - which can be any number of things (but not that 
many really - there aren't THAT *many* ways to gather recon), and he 
tries something against SMTP...
The user may also attempt something horizontally (against one machine on 
many ports) or vertically (against many machines on one port), etc.

> Having run one or two firewalls and NIDS setups
> myself, I'm not clear on the benefit of this beast
> compared to either inline IPS or IDS plus firewall
> blocking (or a firewall and patched servers, while I'm
> going that way).

Simple benefit is, you can put it on your network, not monitor it at 
all, and it would do it's job.

More complicated benefit is, it will catch attacks, new worms, etc. 
regardless of there being a signature for it, and without (at least 
shouldn't be) any false positives (under their definition).

> Stupid question - if my perimeter devices, including
> DMZ servers, are patched, why the heck would I want to

So? What if it is a 0day? What if there is no patch yet? What if it is a 
port scan? What if it is any number of other things? (some of which you 
may not personally care about)

> send back _any_ data to an attacker?  I guess if your
> servers weren't patchable for some reason, maybe you'd
> want to fake that they really are.  Um, okay. 
> Probably better ways to handle that.  I would think

It's an issue of if you want to run an honey pot and look all happy and 
shiny to the attackers, or not. It isn't necessarily about their product.

> that if my perimeter is properly locked-down, I'm
> quite happy for an attacker to scan it and figure that
> out for themselves - assuming they get much of a scan
> past IPS/IDS/firewall.

It isn't a regular IPS.

> What am I missing?  Thanks for the feedback.

No technology is perfect, and they seem to learn and evolve with time as 
expected. It isn't for everybody, and trusting it is not a simple issue 
for a paranoid mind, but hey - that's the same with any IPS or anything 
that blocks automatically.

If you already have it - upgrade, why not? If you don't I'd strongly 
recommend it, but not if what you want is an IPS with shiny and cool 
signatures.

Now, I don't speak for ForeScout, so I may have things wrong. All I am 
is a guy who tested the product.

Try seeing what the point of this product it. Before I got it, I really 
didn't like it and kept expecting something different from it.. heck, I 
even blamed it for some DDoS, but it isn't a DDoS mitigation tool, is it 
now?

Use this chance to see how it works, and reach your own conclusions. :)

        Gadi Evron.

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