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Re: [LUG] Virus scanners??

 

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jody salt wrote:
|
| Its was just that a few years ago I was slapped by the
| slapper worm.... which brings to my next question:
|
| Is there a good mailing list for the notification of
| security holes in GNU software, e.g. apache, samba
| qmail etc....

Neither Apache nor qmail are even licenced using the GNU licences, much
less GNU project code.

Samba is licenced under the GPL, but is not as far as I know part of the
GNU project (I'm guessing if you run free software everywhere your need
for Samba is pretty minimal?!).

| I guese its just a matter of keeping up with security
| patches.

In general each distro has a mailing list, and update procedures. So
check the distro site, you can follow the more general lists of problems
but unless you have a lot of time and knowledge you'll probably not be
able to tell what is applicable/important.

I think the list membership is unduely optimistic over the question of
malicious code on GNU/Linux.

However the traditional MS Windows style antivirus approach of looking
for virus signatures is pretty pointless if there are no major viruses
in the wild. As by definition any new significant virus won't be in that
signature file, and given the big use of GNU/Linux with exposure is
Apache, you can bet if and when it gets a nasty worm it will spread
everywhere it can VERY quickly.

Similarly with no or very few successful exploits in the wild, even
approaches that look for common patterns of behaviour are almost by
definition doomed to fail, as there is very little successful malware to
generalise from.

Currently the most likely vector for spread is I would guess either a
buggy Apache module, or a suspect web application (think automated
exploit of weaknesses in one of the big web content management systems).
Some sources are already claiming that Apache based web services are
already attaining a similar level of defacement activity to Windows,
precisely due to the commonality of higher level web applications.

Keeping upto date with security patches suffers similar weaknesses as
the signature based antivirus approach, it does nothing to stop the
initial spread if it is based on a new weaknesses.

As such you can use intruder detection and fingerprinting systems to
spot a compromise, but most of your effort is probably better spent
ensuring the software selection you use is as robust as possible, and
that you block unneeded or unwanted services.

Whilst there are structural reasons why viruses and other malware are
not as common on Linux and Unix systems, a meaningful security
architecture being one (contrast "XP Home"), there is limited "defence
in depth".

I also have some concerns about the assumption that free software
project correct bugs quicker, or more comprehensively. Certainly some
key projects (BIND, Apache etc) are patched quickly, and bugs get fixed
in security sensitive areas.

But there are a LOT of exploitable bugs on most desktop GNU/Linux
desktops that have not been fixed, just glance through the Debian bug
tracking system for a selection. And I suspect a lot of servers out
there have software with known vulnerabilities.

As such it is possible to conceive of malware exploits through projects
like Mozilla, GNOME, and common email clients. Certainly none of these
are as ubiquitous as the common Microsoft application software on
Microsoft Windows, but it would be naive to assume that there is any
serious protection beyond that provided by your last backup.

I think the SCANIT report comparing IE and Mozilla browsers summed up
the current status nicely. It suggests that known exploits in the
browser meant IE users were vulnerable to known remote code exploits 98%
of the time, and Mozilla users 15% of the time (oh and Opera 17%, and
note Mozilla on MACOS gets a special mention).

If one application can leave you open to known remote exploit 15% of the
time, what proportion of the time do you think you are genuinely "safe"
against known exploits with a desktop with say 12 main applications running?

The only way we will improve security substantially in the short term is
to migrate to safer underlying libraries, in the manner of Trustix, and
some of the other security hardened GNU/Linux distros.

In the longer term we can deploy more code written in type safe
languages, and deploy more sophisticated security systems (SELinux got
mentioned).

Anyone who thinks that if GNU/Linux (or MACOS) had the market share of
Windows, that malware wouldn't be a problem is living in cloud cuckoo
land. Malware might be much less of a problem in such circumstances than
it is now, we would almost certainly survive without antivirus software
(heck you can nearly do that with Windows already if you are
knowledgable) but it wouldn't go away completely.
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