Security Basics mailing list archives

Re: 543.rar attachment


From: "David J ONEILL" <David.J.Oneill () state or us>
Date: Tue, 15 Mar 2005 10:50:24 -0800

I hope you were being rhetorical in your questions.  If not, you clearly
do not have enough experience to be discussing what should and should
not be allowed via email.

As a state agency, we work with many other organizations (large and
small), some only have regular email access to work with.

David J O'Neill
Senior Systems Analyst
State of Oregon
Department of Human Services
Office of Information Services
PH# 503.378.2101 ext. 280
email david.j.oneill () state or us

Jonathan Loh <kj6loh () yahoo com> 03/15/05 10:44AM >>>
Ok let's take it from that standpoint then.  All executables are not
evil.  

All computer users are not evil.  Does this mean we will shut down our
firewalls and let everybody access our internal networks?  

I'm not saying stop all email traffic, far from it, just all archives. 
There
are many ways of getting archives in.  But oh well to each his own. 
Have you
heard of ssh/scp/sftp for deployment of programs?  Along with perhaps
an email
stating where to get your program and how to install it?
--- David J ONEILL <David.J.Oneill () state or us> wrote:

And your point is ....

Not all executable files are evil, the source of the file must be
considered.  Sometimes, such as client server applications,
executable
files must be deployed with the associated resource files.  And with
the
limitations on attachment sizes placed on commercial email systems,
one
needs all the compression one can get.

David J O'Neill
Senior Systems Analyst
State of Oregon
Department of Human Services
Office of Information Services
PH# 503.378.2101 ext. 280
email david.j.oneill () state or us 

Jonathan Loh <kj6loh () yahoo com> 03/14/05 10:41PM >>>
Ok let's have a reality check.  
Blocking archive files is easy by just writing a simple filter
looking
for
various extensions.  Pruning executable files means you will have to
use that
same filter, open the archive, either extract the whole thing,
delete
the
executables, and repackage the whole thing, or delete the
executables
in place.
 
Everyone can split large application files, or can be taught how,
and
send them
to be repackaged.  Ever wonder how TCP and UDP work?   

--- David J ONEILL <David.J.Oneill () state or us> wrote:
Gee, why not just block ALL email communication.  That would save
you
some work too.

Archive files are a necessary part of communication and very
beneficial
in saving bandwidth.

Let's have a reality check ....

David J O'Neill
Senior Systems Analyst
State of Oregon
Department of Human Services
Office of Information Services
PH# 503.378.2101 ext. 280
email david.j.oneill () state or us 

Jonathan Loh <kj6loh () yahoo com> 03/14/05 02:21PM >>>
Ok that's a solution.  But what I want to ask you is this.  How
much
overhead
does it take to do this?  Blocking archive files would be an
easier
method with
little overhead.  Possibly with a reply to sender that your site
does
not
accept archive files.  
--- Kinnell <kinnell.t () gmail com> wrote:
On the network I'm a member of we block all exe files sent
inside
the
rar or zip, so even if it is sent the file will be 0byted. 
Wouldn't
that be a better method?  otherwise if you block all bz2, zip,
rar,
etc... then you will block a lot of useful communication

-Kinnell

On Fri, 11 Mar 2005 16:49:16 -0500, adisegna () siscocorp com 
<adisegna () siscocorp com> wrote:
Sean, I have to disagree with you. Any file that that can
encapsulate an
executable file should be blocked (IMO). ZIP files are one of
the
biggest carriers of malicious content these days. I don't make
it
a
habbit of trusting my users no matter how many times they get
trained.
RAR extraction tools are not part of the software image policy
on
my
network so users are oblivious to the file blocking. What is
your
solution?

Thanks

AD
Information Technology Group
Security Identification Systems Corporation

-----Original Message-----
From: Sean Crawford [mailto:sean01 () accnet com au] 
Sent: Tuesday, March 08, 2005 9:39 PM
To: security-basics () securityfocus com 
Subject: RE: 543.rar attachment

---> -----Original Message-----
---> From: adisegna () siscocorp com
[mailto:adisegna () siscocorp com] 


---> Subject: RE: 543.rar attachment

---> I just recently got the same executable inside .rar. I
extracted
the
---> dddd.exe and ran a scan on it. Norton Corporate 9.01
didn't
find
---> anything (as of 4 days ago). I wasn't about to double
click
this
exe on
---> my corporate network. Block the rar extension on your
mail
server.
--->

rar is a valid compression format...blocking it isn't a very
good
solution.

2 cents.

Sean





            
__________________________________ 
Do you Yahoo!? 
Yahoo! Small Business - Try our new resources site!
http://smallbusiness.yahoo.com/resources/ 


__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com 




                
__________________________________ 
Do you Yahoo!? 
Yahoo! Small Business - Try our new resources site!
http://smallbusiness.yahoo.com/resources/ 


Current thread: