December 2003 - cypherpunks-legacy

SSL Man-in-the-middle
by David J. Bianco 17 Dec '03

17 Dec '03

Has anyone given much thought to the feasability of a man-in-the-middle attack against an SSL (or other similar) transaction? To me, the possibility seems obvious, so I figure it must have been discussed before, though I haven't seen it. The basic idea is pretty simple, really a flaw in the user interface of the browser more than a flaw in SSL. Neither browsers nor servers routinely validate that they are communicating with the entity they think they are. Sure, with netscape you can ask for the document information window, which shows the server's public key information, but this isn't a common action among users, and certainly isn't something you'd want to do for every page you viewed. The only readily accessible information about security is that blue key at the bottom of the netscape window. Netscape docs tell you that if that key is blue, your transaction is "secure." In reality, the only thing that key means is that you've negotiated a session key and are encrypting your communications. It says nothing about the fact that you're actually communicating with the correct party. Authentication is a large part of security, and Netscape doesn't make that information conveniently available. Consider the following example. Bob wants to communicate securely with Alice. He fires up his "secure" browser, looks up Alice's address in the DNS and makes a connection. He then sends Alice a document and disconnects. Now consider the following attack on the scenario: Bob still wants to communicate with Alice. He fires up his browser and looks up Alice in the DNS. Mallet, who wants the information Bob's sending, has subverted Alice's DNS server and replaced Alice's IP address with his own, making a note of the proper value. Thus, when Bob looks up Alice's address in DNS, he gets the wrong information and contacts Mallet instead. Mallet performs the SSL protocol with Bob, pretending to be the server, and then with Alice, pretending to be the client. Since neither the browser nor the server perform any authentication checks, neither Bob nor Alice know they are really speaking to Mallet. The best Alice can do is check the IP address of the client she's speaking to, but if Mallet has his own DNS, he can make the IP address map to whatever name he wants, including Bob, in order to fool alice. Even if Alice doesn't depend on the DNS for IP resolution, probably doesn't know that the IP address in question is really Mallet's, since it looks just like any other IP address to her. In this scenario, Bob gets a warm fuzzy since his key is blue and he knows his information is being encrypted as it goes out. Alice has a smaller fuzzy, since she believes the transaction is secure from prying eyes. Mallet has a *really big* fuzzy, since he's able to read the data Bob sends, decrypt it, save it, then re-send it to Alice. I've read through the SSL spec, and it provides authentication for both the server and the client, but these features are rarely used, probably because they are somewhat inconvenient for the user. A good first step would be to include the IP address of the server in the certificate signed by VeriSign. In this way, browsers could perform automatic checks that the IP address in the certificate is actually the one that's being communicated with. This does raise other questions (such as protecting from IP spoofing), but IMHO would be a good way of providing an automatic "first check" without inconveniencing users. The added inconvenience of obtaining a new certificate when your server's IP address changes is fairly minor, and could be viewed as necessary overhead for doing secure transactions via the Net. -- ========================================================================== David J. Bianco | Web Wonders, Online Oddities, Cool Stuff iTribe, Inc. | Phone: (804) 446-9060 Fax: (804) 446-9061 Suite 1700, World Trade Center | email: <bianco(a)itribe.net> Norfolk, VA 23510 | URL : http://www.itribe.net/~bianco/

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Fax Number List
by K. M. Ellis 17 Dec '03

17 Dec '03

I promised last week that I would send this out when the idea of a blanket-fax-campaign for a c-punks press release was being discussed. Sorry it took me so long to get around to it, but here it is. I was mistaken in my original posting: it includes neither the Fox Network _nor_ the Eye on America show, but I'm sure we'll find those numbers somewhere. I got it from the Iron Feather Journal, volume 14. I have no reason to believe that any of these numbers are incorrect, but some of them may have changed. Also: personal apologies to anyone who considers this to be noise. Please restrict all flames to private e-mail. Anybody wanna fax Ted Turner? :) ABC 20/20 NY 1-212-456-2969 ABC World News NY 1-212-456-4968 Ann Arbor News Ann Arbor, MI 1-313-994-6879 AP Los Angeles 1-213-748-1200 AP San Diego 1-619-291-2098 AP Washington, D.C. 1-202-828-6422 AP (Broadcast) Washington, D.C. 1-202-955-7367 Associated Press Boston, MA 1-617-338-8215 Associated Press Los Angeles 1-213-748-9836 Steve Loeper Associated Press Phoenix, AZ 1-602-254-9573 Assignment Editor Associated Press San Francisco 1-415-552-9430 Bill Schiffmann Associated Press MN Minneapolis, MN 1-612-332-4245 Boston Phoenix Boston, MA 1-617-536-1463 Boulder Daily Camera Boulder, CO 1-303-442-1508 C-SPAN Washington, D.C. 1-202-737-6226 Sarah Traheorn CBS NY 1-212-975-1519 CBS Washington, D.C. 1-202-659-2586 CBS (Radio) Washington, D.C. 1-202-659-5578 CBS Eve News NY 1-212-975-2115 CBS Morning Washington, D.C. 1-202-331-1765 CBS News Los Angeles 1-213-651-0285 Jennifer Siebens CBS News San Francisco 1-415-362-7417 John Blackstone CBS TV Los Angeles 1-213-651-0321 CBS TV San Francisco 1-415-362-7417 Ch. Sci Monitor Washington, D.C. 1-202-223-3476 Chicago Sun-Times Chicago, IL 1-312-321-3084 Chicago Tribune Chicago, IL 1-312-222-3143 CNN Los Angeles 1-213-460-5081 CNN San Francisco 1-415-398-4049 CNN President Atlanta, GA 1-404-827-1575 Ted Turner Coloradoan Fort Collins, CO 1-303-224-7726 Denver Post Denver, CO 1-303-820-1369 Der Spiegel Hollywood, CA 1-213-851-9867 Frances Schoenberg Detroit News Detroit, MI 1-313-222-2335 Gannett Washington, D.C. 1-202-243-0190 Gannett News Service Sacramento, CA 1-916-446-7326 Becky Lavally Good Mng America Washington, D.C. 1-202-887-7685 Mother Jones San Francisco, CA 1-415-863-5136 Douglas Foster NBC Washington, D.C. 1-202-362-2009 NBC (Radio) Washington, D.C. 1-703-685-2197 NBC News Burbank, CA 1-818-840-4275 Heather Allan NBC News New York, NY 1-212-956-2140 NBC News San Francisco, CA 1-415-441-2823 David Burrington NBC News President New York, NY 1-212-315-4037 Michael Gartner NBC TV Los Angeles 1-818-840-4275 NBC TV San Francisco, CA 1-415-441-2823 Newsweek Los Angeles, CA 1-213-444-5287 Managing Editor Newsweek New York, NY 1-212-421-4993 Jonathan Alter Newsweek Washington, D.C. 1-202-783-6512 NPR Radio San Francisco, CA 1-415-553-2241 NY Times New York, NY 1-212-556-4603 PBS Alexandria, VA 1-703-739-0775 Pulse! West Sacramento, CA 1-916-373-2480 Laurie Macintosh Rainbow Coalition Washington, D.C. 1-202-728-1192 Reuters Los Angeles 1-213-622-0056 Rocky Mountain News Denver, CO 1-303-892-5499 Scripps Howard Washington, D.C. 1-202-408-8116 Shareware Magazine Sunnyvale, CA 1-408-730-2107 Tracy Stephenson Time San Francisco, CA 1-415-434-5209 Paul Witteman Time Magazine NY 1-212-522-0451 UPI Boston, MA 1-617-338-9774 Barry Fly UPI Los Angeles 1-213-620-1237 UPI San Francisco 1-415-552-3585 Bill Bucy UPI Seattle, WA 1-206-283-0408 Penny Spar UPI Washington, D.C. 1-202-789-2362 UPI (Radio) Washington, D.C. 1-202-842-3625 US News & Wrld Rprt Washington, D.C. 1-202-955-2713 USA Today Washington, D.C. 1-202-276-5527 Utne Reader Minneapolis, MN 1-612-338-6043 Whole Earth Review Sausalito, CA 1-415-332-2416 Kevin Kelly kelli(a)zeus.towson.edu Geek Code v3.0 http://zeus.towson.edu/~kelli/ GAT dx s++:- a-- C++ uu+++ P+ L++ E- W++ N K W--- O- M- V-- PS+++ PE- Y++(-)> PGP+>++ t+ 5 x+ R tv b+++ DI- D--- G e h* r+ z** Diverse Sexual Orientation Coll.Towson State University DSOC(a)zeus.towson.edu "All the world will be your enemy, Prince With The Thousand Enemies. . . And whenever they catch you, they will kill you. But first, they must catch you. . ." -Richard Adams

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Re: Exchange random numbers (was: Re: netscape's response)
by David_A Wagner 17 Dec '03

17 Dec '03

In article <199509211852.LAA22259(a)Csli.Stanford.EDU> you write: > > | If I only ever give out a hash of my seed, and only ever *add* any received > | info to my seed (and stir it in well), how can anyone find out anything? > | (Apart from hash weaknesses.) > > Giving out contribution: > MD5(select_bits(my_seed, start_bit, stop_bit)) -> remote > Taking in contribution : > my_seed = my_seed XOR > ((select_low_bits(remote_contrib, contrib_width) << contrib_area) > People seem to think this kind of thing is obviously safe. I'm not yet convinced. By xoring in a quantity *chosen by your adversary*, you're essentially allowing related-key attacks on your stream cipher. (Your PRNG is just a stream cipher, keyed with my_seed.) Noone knows how secure most ciphers are against related-key attacks: related-key attacks are known to be very powerful (often more powerful than any other type); but very little research on this topic is available. You're treading on unknown ground. There's the also a small error in your specific algorithm. Let n = stop_bit - start_bit; presumably n is much less than the length of your seed. Then a brute-force search over n bits will recover n bits of the seed -- this is a much faster cryptanalysis than a brute force over all bits of the seed. This can probably be fixed by something like MD5(select_bits(MD5(my_seed))) -> remote, but the related-key uncertainties still remain.

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Archives current again
by Leslie Todd Masco 17 Dec '03

17 Dec '03

-----BEGIN PGP SIGNED MESSAGE----- I've just updated the archives (http://www.hks.net/cpunks/index.html) To bring everybody up to date on what's happening: Hypermail simply isn't up to this size of an archive. All sorts of bugs are coming out into the open, so I've been implementing a system designed for large archives. Alas, reality has intruded and I haven't had the time to finish it. So, I'll be updating the archives by hand from time to time until I can get the new system on line. Sorry 'bout that, folks, but you get what you pay for. - -- Todd Masco | "life without caution/ the only worth living / love for a man/ cactus(a)hks.net | love for a woman/ love for the facts/ protectless" - A Rich Cactus' Homepage - --- [This message has been signed by an auto-signing service. A valid signature means only that it has been received at the address corresponding to the signature and forwarded.] -----BEGIN PGP SIGNATURE----- Version: 2.6.2 Comment: Gratis auto-signing service iQBFAwUBMGgVHCoZzwIn1bdtAQE0gwF/dQiO+4lTabDqAt0SgyHmEJSKXgCABGa6 kEOsJIgd/4uIUzrunV+fXBucevMsW4yG =BngF -----END PGP SIGNATURE-----

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Re: Hack Microsoft?
by RJ Harvey 17 Dec '03

17 Dec '03

At 10:33 AM 9/26/95 EDT, Dan Bailey wrote: >On Tue, 26 Sep 1995 00:04:08 -0400 (EDT) you wrote: > >> >> >> Microsoft recently got C2-security status approved for Windows NT by >>the National Computer Security Center, a division of the NSA. They >>are supposed to put systems through "laborious testing and review" before >> If Cypherpunks can find flaws that the NSA can't, or won't divulge, >>what does that say about their so-called COMSEC ability. >> >For fun ways to hack NT, check out http://www.somar.com/security.html. > Some of these are really laughable. You can use NT's LogonUser API >call to repeatedly guess passwords until you hit it, since NT offers >no way to limit number of login attempts. I don't believe that's correct; under User Manager, select the Account option under the Policies menu item; it lets you select whether to lock-out the account after a given number of invalid logon attempts, and to set the number. The main problem here is that by default, I don't believe the 'lock out' option is enabled (and thus, brute-force attempts at Guest or a similar account might indeed work). rj --------------------------------------------------------- R. J. Harvey email: harveyrj(a)vt.edu WWW for job analysis/personality: http://harvey.psyc.vt.edu/ PGP key at http://harvey.psyc.vt.edu/RJsPGPkey.txt

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Re: Hack Microsoft?
by Mike Markley 17 Dec '03

17 Dec '03

Dan Bailey <dan(a)milliways.org> writes: | There also is no way to stop remote users from modifying the | registry. *Any* user with an account can remotely dump and modify the | system registry. So in theory you can write a bruteforce program to | keep guessing until it gets a password, then modify the registry to | make the system to "interesting" things. The worst part of all this | is that the Registry is very poorly documented, MSoft must consider | most of that info "confidential." | Fortunately, when using NT's SMB services such as drive and file | sharing, passwords are never sent in the clear. Just make sure you | disable that "Guest" account.:) This is not entirely true. If I log in as 'guest' I cannot modify just any key in the registry. I can only modify the ones that I have permissions to change. Also if you know what you are doing you can set permissions on any key in the registry so that it can't be modified by just anyone. I can also modify the account permissions so that if a logon attempt fails, after a specified number of retries the account is locked and will not accept logons until the administrator unlocks the account. I'd recommend that you get a copy of Windows NT and the Windows NT Resource Kit, install it and play around with the security system before you make generalized statements about it. Mike. ===================================================== Mike Markley <mmarkley(a)microsoft.com> I'm not a Microsoft spokesperson. All opinions expressed here are mine. =====================================================

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RE: More on "Entropy"
by tomw＠orac.engr.sgi.com 17 Dec '03

17 Dec '03

In article <DFHJDD.Ap(a)sgi.sgi.com>, David Van Wie <dvw(a)hamachi.epr.com> writes: > David Van Wie wrote: >>> The entropy E is defined by the sum across n states of -P_i log_2(P_i), > Timothy C. May wrote: >> Hah! Another physicist converted to the information-theoretic view of > entropy! > Indeed. I was able to track down the literature, and it is most > interesting. I am still a little bit skeptical of the "superset including > thermodynamic entropy" school of thought, but I haven't finished reading all > of the materials yet! Clearly, the IT "version" of entropy is a well > defined and useful thing.... We used this formulation of entropy in Statistical Mechanics. It's especially useful in Quantum Thermo where you can actually enumerate all of the states instead of relying on probabilistic arguments. -- Sure we spend a lot of money, but that doesn't mean | Tom Weinstein we *do* anything. -- Washington DC motto | tomw(a)engr.sgi.com

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Re: Golden Coy Freeh
by mkj＠october.ducktown.org 17 Dec '03

17 Dec '03

PGP message

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Re: Security Update news release
by shamrock＠netcom.com 17 Dec '03

17 Dec '03

-----BEGIN PGP SIGNED MESSAGE----- In article <9509251617.ZM167@tofuhut>, jsw(a)netscape.com ("Jeff Weinstein") wrote: >-- >--PART-BOUNDARY=.19509251617.ZM167.tofuhut >Content-Type: text/plain; charset=us-ascii > > Here is the press release we put out this morning regarding the fix >for RNG seed and stack overflow problems. Do the new versions use PGP's randseed.bin? If Netscape even only looks at data used to keep PGP secure, Netscape will be banned from my computer and every computer I am responsible for. -- For good. - -- - -- Lucky Green <mailto:shamrock@netcom.com> PGP encrypted mail preferred. - --- [This message has been signed by an auto-signing service. A valid signature means only that it has been received at the address corresponding to the signature and forwarded.] -----BEGIN PGP SIGNATURE----- Version: 2.6.2 Comment: Gratis auto-signing service iQBFAwUBMGduUCoZzwIn1bdtAQFEgwGA3265JY1cahyqqd2VEe+1RPXI96DQBPRV r1EWdjxzjgXvxplLMagh9yWOPBq9OKRX =F3qb -----END PGP SIGNATURE-----

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Re: Netscape "random" number seed generator code available
by shamrock＠netcom.com 17 Dec '03

17 Dec '03

-----BEGIN PGP SIGNED MESSAGE----- In article <199509251159.EAA08528(a)mycroft.rand.org>, jim(a)acm.org (Jim Gillogly) wrote: >I'm nervous enough about all the Easter Eggs that have been reported in >Netscape, like the secret keystroke shortcut to get to Fishcam, or the >different behavior it exhibits when it finds a certain obscurely-named >directory at the top level. Would you please elaborate? TIA, - -- - -- Lucky Green <mailto:shamrock@netcom.com> PGP encrypted mail preferred. - --- [This message has been signed by an auto-signing service. A valid signature means only that it has been received at the address corresponding to the signature and forwarded.] -----BEGIN PGP SIGNATURE----- Version: 2.6.2 Comment: Gratis auto-signing service iQBFAwUBMGdsfSoZzwIn1bdtAQG3ZwGAk5ZFceYsUmo9OgQJ9oVZGcNcXnorr9a2 cLP/xy3vB/COr3uKjfr0mcYY6JMMLxfa =nXHi -----END PGP SIGNATURE-----

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