Security Basics mailing list archives

Re: PPTP VERY long & strong passwords - Strong enough ?


From: Micheal Espinola Jr <michealespinola () gmail com>
Date: Tue, 1 Mar 2005 13:08:26 -0500

1.  Yes.
2.  Not that I have seen.
3.  Not in an automated fashion, if thats what you are asking. But any
Cert can be exported/imported manually.
4.  Not sure, nor have I heard of that issue before. Are you sure you
have BlackIce configured properly?



On 1 Mar 2005 14:01:09 -0000, bla bla <poizen_ () hotmail com> wrote:


Hi !

4 questions:

1. I use Win2003 PPTP VPN. I've gone through some of past posts & replies regarding PPTP (MS-CHAPv2) and came across 
this:

"Finally, I want to state this: using long, very random password moves
the PPTP attacks from the realm of the practical back into the
theoretical. TO be sure, PPTP is 65,000 times easier to crack because of
a flaw in the authentication protocol. But if you use 12-character (out
of 95 "type-able" ASCII characters) randomly-generated passwords, you
get about 2^79 possible combinations. Even with the 2^16 advantage the
flaw in PPTP provides, it is still impractical for anyone to break the
tunnel without tens of millions of dollars in investment. The NSA or
distributed.net could break it in a few months, but that's about the
only adversaries you'd need to worry about."

Link: http://www.securityfocus.com/archive/50/330874/2005-02-26/2005-03-04/2

Do you guys agree ?
Are there any other (then weak\small passwords) exploits I should be aware of ?
BTW, all vpn accounts set to "never expired" so that any possible "renew password" hack for stealing passwords can 
ever take place (passwords will be changed manually on a monthly basis-it's only ment for a few users).
Also disabled this via the rras policy.

2. Are there any patches\fixes in Win2003 SP1 (ETA 28/3/05) concerning this ? has anybody encountered any problems in 
the SP1 beta2 ?

3. Does anybody know of a hack that will allow to map certificates to user account WITHOUT active directory (the 
server is a stand alone\not in a domain env.) ?

4. I'm also using ISS Blackice (Host IDS+Firewall, ver 3.6coa) on that server (I know-it's not supported by ISS on 
Win2003, bla bla bla...). it works great with pptp but intercepts l2tp\ipsec (MS-CHAPv2) login attempts as 
UDP_SHORT_HEADER and UDP_PROBE_OTHER intrusions (the vpn host is xpsp1). I've tried opening all the relevant ports + 
configuring the app to ignore these type of intrusions + trusting all communication from the vpn host ip, but to no 
avail. only stopping the firewall does the trick.
Any thoughts ?
Does Blackice has a forum somewhere ?

Thnaks guys !



-- 
ME2

my home: <http://www.santeriasys.net/>
my photos: <http://mespinola.blogspot.com/>


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