December 2003 - cypherpunks-legacy

Re: Reordering, not Latency (Was: Re: Remailer)
by wcs＠anchor.ho.att.com 17 Dec '03

17 Dec '03

> > In recent discussions, the consensus > > was that message reordering was superior to (and the actual intent of) > > latency. Reordering is not sufficient, a form of latency is required > > to make it effective. > I have literally hundreds of messages archived from the CP list of > several months back where Eric Hughes repeatedly states that reordering, > not latency, is the key. Reordering of a sufficient magnitude will > introduce latency inherently. Effective reordering is the key - as Louis Cypher's article showed, there are forms of reordering which are NOT effective, though the requirement for latency is really a consequence rather than a direct requirement. There are six+ classes of packets that can go through a remailer: 1) Real packets from outside to be remailed to outside. 2) Hostile packets from traffic analysts* outside to outside. 3) Real packets from outside to users on the remailer itself. 4) Real packets from the remailer itself to outside. 5) Cover traffic packets from the remailer to outside. 6) Cover packets from outside friendly remailers. Ingoring categories 3-6 for the moment, the problem with reordering is that the remailer needs to reorder n _real_ packets to get a certain level of security, but can't really tell real packets from hostile ones. If the algorithm is simply to reorder and retransmit batches of n packets, either en masse or in a stream basis as Louis suggests, the analysts can surround each real packet with n hostile packets from known destinations to known destinations and therefore be able to pick out the one real packet on the outbound. The effect of latency L is to provide a reasonable probability that n real packets will have arrived during time L, so the addition of hostile packets does not prevent the mixing between the n real packets. Outbound cover traffic is helpful, but unless it targets the same destinations as the real traffic with some probability, it may not be sufficient to prevent long-term pattern analysis (and cover traffic is mainly useful when sent to other remailers and their co-conspirators; cover traffic sent to a newsgroup or innocent member of the public is generally recognizable as such...) Inbound cover traffic is great, of course - I'm not sure if it totally substitutes for real traffic? Its best use is in systems where real traffic users chain between remailers which also carry cover traffic between them, but there's still some information that can potentially be gleaned about a small** remailer-cloud viewed as a whole by analysts forcing lots of traffic through the cloud, unless the remailers implement adequate reordering models. [* I was going to refer to traffic analysts by the usual term Bad Guys, but someday one of us good guys may want to break into a net run by Bad Guys, so I decided to stay neutral here :-)] [** The current 15-20 remailers are still a relatively small cloud.] Bill

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white noise remailer
by rkmoore＠iol.ie 17 Dec '03

17 Dec '03

I'm new to all this so please pardon my ignorance, but are you guys consdidering the following approach: The remailer transmits a constant bandwidth of outgoing messages of all about the same size to a uniformly distributed range of target addresses. Incoming messages are randomly dispersed within this stream, packed out to the standard size. -rkm --- Richard K. Moore - rkmoore(a)iol.ie - Wexford, Ireland - fax +353 53 23970

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Even more unix holy war. Was "Clinton freezes U.S. assets .."
by jamesd＠com.informix.com 17 Dec '03

17 Dec '03

To summarize this thread, and I hope end it. The fans of unix correctly point out that unix can, in principle, be configured to be really nice. Well so can a molten lump of pig iron, in principle, be configured to be something really nice. Out in the real world people do not like dealing with a molten lump of pig iron, and so it is usually not configured to be really nice, which is why we see people editing with vi and publishing with latex. Now sometimes MIS creates a tiny little reserve where things really are really nice, and the secretaries are herded into this little reserve, and within this little reserve everything is almost as nice as windows. (Unless of course you want to cut and paste formatted text and graphics between windows, under the sun OS, but hey, that is an arcane operation that the normal user would never want to do. Right? You cannot really expect MIS to help such special power users can you?) And that is what Bill O'Hanlon meant when he said that for ordinary naive users who had not been exposed to either operating system, unix was no worse than dos. Herd them into the reserve and keep them there, and it is indeed no worse than dos. But the reserve is not really the whole operating system, it is just a little area of safety. And as soon as somebody strolls outside the little reserve to do something that MIS has not specifically planned for and arranged, half a ton of molten pig iron pours down on them, and MIS says: "Hey, don't do that." --------------------------------------------------------------------- | We have the right to defend ourselves | http://www.catalog.com/jamesd/ and our property, because of the kind | of animals that we are. True law | James A. Donald derives from this right, not from the | arbitrary power of the omnipotent state. | jamesd(a)netcom.com

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Re: white noise remailer
by Jaeson.M.Engle＠josaiah.sewanee.edu 17 Dec '03

17 Dec '03

-----BEGIN PGP SIGNED MESSAGE----- This is an interesting approach. It could even contain a small set of PGP'd messages like "This is the sound of white noise on the Internet" and "Have fun breaking this one?" In the even someone took the time to break the pgp... >I'm new to all this so please pardon my ignorance, but are you guys >consdidering the following approach: > >The remailer transmits a constant bandwidth of outgoing messages of all >about the same size to a uniformly distributed range of target addresses. >Incoming messages are randomly dispersed within this stream, packed out to >the standard size. > >-rkm > > >--- > >Richard K. Moore - rkmoore(a)iol.ie - Wexford, Ireland - fax +353 53 23970 -----BEGIN PGP SIGNATURE----- Version: 2.6ui iQCVAgUBLyhlIUiLvmPjc4XdAQFRgwQAiSJr09cQav2c+kqz+6a8NSyh4BXf1prx 0hDbn31MlBBWTnezk/+PSCmfE9eXZwLbrLDCtUwIoudhIYxTqAzJV10GK0gWyF7O 6iKg6LTEgsa4DfJC2uc7Knrdj9ln9LK6qy8/I5zM5QZdfZHwYEuEcGS5aPIHdYGT SbKsnUi0rHI= =kUQl -----END PGP SIGNATURE----- aka: (-: Jaeson M. Engle || jme(a)josaiah.sewanee.edu :-) (-: www server: http://josaiah.sewanee.edu/ :-) (-: It's February 8th! IT'S TIME!!! Ask me for details!:-) (-: Finger 'jme(a)josaiah.sewanee.edu' for my Public :-) PGP block.

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Re: Reordering, not Latency (Was: Re: Remailer)
by Andrew Lowenstern 17 Dec '03

17 Dec '03

> Adam Shostack says: > > It may be that the FBI has a couple of Suns handling the whole > > remailer network right now. Perry Metzger replies: > If they are doing that, they are violating the ECPA. They are > allowed to monitor only those things they have a warrant to monitor > (with, of course, all those lovely National Security exceptions). > This is not to say that it isn't being done, but it can't be used > in court. Is this even technically possible? That is, wholesale monitoring of disparate portions of the net from a single access point. Given the distributed and dynamic properties of the Net this would seem impossible. To monitor the entire remailer network an attacker would have to setup packet sniffers upstream from each and every portion of the Net that contained a remailer, wouldn't they? I suppose an extremely resourceful attacker could monitor traffic at crucial points (i.e. transcontinental feeds, points on the NFSnet, CIX, etc...), but there are so many private connections linking networks that it would be very difficult indeed to sniff out every bit of remailer traffic. Is having every bit of remailer traffic necessary for traffic analysis? Or would having a good percentage of it be sufficient? andrew

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<none specified>
by Anonymous 17 Dec '03

17 Dec '03

-----BEGIN PGP SIGNED MESSAGE----- My appologies if this has already made it to the list. In article <D2wtJC.C8I(a)freenet.carleton.ca> you wrote: : In a previous posting, Farrell McGovern (ai474(a)FreeNet.Carleton.CA) writes: : > CNN Headline news this morning is running a story saying how the : > Internet is so innsecure that "hackers" can access former VP Quale's : > medical records, number of atomic warheads in a certain state and CIA's : > budget. And all ths is supposedly based upon a "breakthrough" that : > "hackers" have made recently. They say that the Internet will not be able : > to be secure for at least 5 years. : Here's more about it! : : Article #36 (36 is last): : Newsgroups: comp.security.announce : From: ecd(a)why.cert.org (Edward DeHart) : Subject: IP Spoofing Attacks and Hijacked Terminal Connections : Date: Mon Jan 23 16:00:37 1995 : ============================================================================= : CA-95:01 CERT Advisory : January 23, 1995 : IP Spoofing Attacks and Hijacked Terminal Connections : ----------------------------------------------------------------------------- : The CERT Coordination Center has received reports of attacks in which : intruders create packets with spoofed source IP addresses. These attacks : exploit applications that use authentication based on IP addresses. This : exploitation leads to user and possibly root access on the targeted system. : Note that this attack does not involve source routing. Recommended solutions : are described in Section III below. : In the current attack pattern, intruders may dynamically modify the kernel of : a Sun 4.1.X system once root access is attained. In this attack, which is : separate from the IP spoofing attack, intruders use a tool to take control of : any open terminal or login session from users on the system. Note that : although the tool is currently being used primarily on SunOS 4.1.x systems, : the system features that make this attack possible are not unique to SunOS. : : As we receive additional information relating to this advisory, we will place : it, along with any clarifications, in a CA-95:01.README file. CERT advisories : and their associated README files are available by anonymous FTP from : info.cert.org. We encourage you to check the README files regularly for : updates on advisories that relate to your site. : : ----------------------------------------------------------------------------- : : I. Description : : This description summarizes both the IP spoofing technique that can : lead to root access on a system and the tool that intruders are using to : take over open terminal and login connections after they get root access. : We are currently seeing attacks in which intruders combine IP spoofing : with use of the tool. However, these are two separate actions. Intruders : can use IP spoofing to gain root access for any purpose; similarly, they : can highjack terminal connections regardless of their method of gaining : root access. : : IP spoofing : To gain access, intruders create packets with spoofed source IP : addresses. This exploits applications that use authentication : based on : IP addresses and leads to unauthorized user and possibly root access : on the targeted system. It is possible to route packets through : filtering-router firewalls if they are not configured to filter : incoming packets whose source address is in the local domain. It : is important to note that the described attack is possible even if : no reply packets can reach the attacker. : : Examples of configurations that are potentially vulnerable include : - routers to external networks that support multiple internal : interfaces : - routers with two interfaces that support subnetting on the : internal network : - proxy firewalls where the proxy applications use the source : IP address for authentication : : The IP spoofing attacks we are currently seeing are similar to those : described in two papers: 1) "Security Problems in the TCP/IP Protocol : Suite" by Steve Bellovin, published in _Computer Communication Review_ : vol. 19, no. 2 (April 1989) pages 32-48; 2) "A Weakness in the 4.2BSD : Unix TCP/IP Software" by Robert T. Morris. Both papers are available : by anonymous FTP from : : ftp.research.att.com:/dist/internet_security : : Bellovin paper: ipext.ps.Z : Morris paper: 117.ps.Z : : Services that are vulnerable to the IP spoofing attack include : SunRPC & NFS : BSD UNIX "r" commands : anything wrapped by the tcp daemon wrappers - site dependent; check : your configuration : X windows : other applications that use source IP addresses for authentication : : Hijacking tool : Once the intruders have root access on a system, they can use a tool : to dynamically modify the UNIX kernel. This modification allows them : to hijack existing terminal and login connections from any user on the : system. : : In taking over the existing connections, intruders can bypass one-time : passwords and other strong authentication schemes by tapping the : connection after the authentication is complete. For example, a : legitimate user connects to a remote site through a login or terminal : session; the intruder hijacks the connection after the user has : completed the authentication to the remote location; the remote site : is now compromised. (See Section I for examples of vulnerable : configurations.) : : Currently, the tool is used primarily on SunOS 4.1.x systems. However, : the system features that make this attack possible are not unique to : SunOS. : : : II. Impact : : Current intruder activity in spoofing source IP addresses can lead to : unauthorized remote root access to systems behind a filtering-router : firewall. : : After gaining root access and taking over existing terminal and login : connections, intruders can gain access to remote hosts. : : : III. Solutions : : A. Detection : : IP spoofing : If you monitor packets using network-monitoring software such as : netlog, look for a packet on your external interface that has : both its source and destination IP addresses in your local domain. : If you find one, you are currently under attack. Netlog is : available by anonymous FTP from : net.tamu.edu:/pub/security/TAMU/netlog-1.2.tar.gz : MD5 checksum: 1dd62e7e96192456e8c75047c38e994b : : Another way to detect IP spoofing is to compare the process : accounting logs between systems on your internal network. If : the IP spoofing attack has succeeded on one of your systems, : you may get a log entry on the victim machine showing a remote : access; on the apparent source machine, there will be no : corresponding entry for initiating that remote access. : : Hijacking tool : When the intruder attaches to an existing terminal or login : connection, users may detect unusual activity, such as commands : appearing on their terminal that they did not type or a blank : window : that will no longer respond to their commands. Encourage your users : to inform you of any such activity. In addition, pay particular : attention to connections that have been idle for a long time. : : Once the attack is completed, it is difficult to detect. However, : the intruders may leave remnants of their tools. For example, you : may find a kernel streams module designed to tap into existing TCP : connections. : : B. Prevention : : IP spoofing : The best method of preventing the IP spoofing problem is to install : a filtering router that restricts the input to your external : interface (known as an input filter) by not allowing a packet : through if it has a source address from your internal network. In : addition, you should filter outgoing packets that have a source : address different from your internal network in order to prevent : a source IP spoofing attack originating from your site. : : The following vendors have reported support for this feature: : Bay Networks/Wellfleet routers, version 5 and later : Cabletron - LAN Secure : Cisco - RIS software all releases of version 9.21 and later : Livingston - all versions : : If you need more information about your router or about firewalls, : please contact your vendor directly. : : If your vendor's router does not support filtering on the inbound : side of the interface or if there will be a delay in incorporating : the feature into your system, you may filter the spoofed IP packets : by using a second router between your external interface and your : outside connection. Configure this router to block, on the outgoing : interface connected to your original router, all packets that : have a : source address in your internal network. For this purpose, you can : use a filtering router or a UNIX system with two interfaces that : supports packet filtering. : : NOTE: Disabling source routing at the router does not protect you : from this attack, but it is still good security practice to : do so. : : Hijacking tool : There is no specific way to prevent use of the tool other than : preventing intruders from gaining root access in the first place. : If you have experienced a root compromise, see Section C for : general : instructions on how to recover. : : C. Recovery from a UNIX root compromise : : 1. Disconnect from the network or operate the system in : single-user mode during the recovery. This will keep users : and intruders from accessing the system. : : 2. Verify system binaries and configuration files against the : vendor's media (do not rely on timestamp information to : provide an indication of modification). Do not trust any : verification tool such as cmp(1) located on the compromised : system as it, too, may have been modified by the intruder. : In addition, do not trust the results of the standard UNIX : sum(1) program as we have seen intruders modify system : files in such a way that the checksums remain the same. : Replace any modified files from the vendor's media, not : from backups. : -- or -- : : Reload your system from the vendor's media. : : 3. Search the system for new or modified setuid root files. : : find / -user root -perm -4000 -print : : If you are using NFS or AFS file systems, use ncheck to : search the local file systems. : : ncheck -s /dev/sd0a : : 4. Change the password on all accounts. : : 5. Don't trust your backups for reloading any file used by : root. You do not want to re-introduce files altered by an : intruder. : : --------------------------------------------------------------------------- : The CERT Coordination Center thanks Eric Allman, Steve Bellovin, Keith Bostic, : Bill Cheswick, Mike Karels, and Tsutomu Shimomura for contributing to our : understanding of these problems and their solutions. : --------------------------------------------------------------------------- : : If you believe that your system has been compromised, contact the CERT : Coordination Center or your representative in Forum of Incident : Response and Security Teams (FIRST). : : If you wish to send sensitive incident or vulnerability information to : CERT staff by electronic mail, we strongly advise that the e-mail be : encrypted. The CERT Coordination Center can support a shared DES key, PGP : (public key available via anonymous FTP on info.cert.org) or PEM (contact : CERT staff for details). : : Internet E-mail: cert(a)cert.org : Telephone: +1 412-268-7090 (24-hour hotline) : CERT personnel answer 8:30 a.m.-5:00 p.m. EST(GMT-5)/EDT(GMT-4), : and are on call for emergencies during other hours. : Fax: +1 412-268-6989 : : CERT Coordination Center : Software Engineering Institute : Carnegie Mellon University : Pittsburgh, PA 15213-3890 : USA : : Past advisories, CERT bulletins, information about FIRST representatives, : and other information related to computer security are available for anonymous : FTP from info.cert.org. : : : : CERT is a service mark of Carnegie Mellon University. : : ------------------------------- : -- : ------------------------------------------------------------------------ : The Information Cowpath is strewn with Meadow Muffins...even the best of : us get the Meadow Muffin Blues every now and then... - --- [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 iQBFAwUBLycwFyoZzwIn1bdtAQH7lQGAqGZx0JupR5oLwwm9wcJkhwZLks3Y1y36 4F9UjunJWFS4sKbts6eLkAT3jakXpTXT =3rGy -----END PGP SIGNATURE-----

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"Subway" remailers
by xpat＠vm1.spcs.umn.edu 17 Dec '03

17 Dec '03

Need ideas/comments: I have been modeling remailer scenarios using IBM VM/ESA virtual machines. After fwaffing a bit, looking at the traffic analysis concern, and taking note of some of the probability work posted recently, I thought I might throw this idea out for a sanity check: "Subway" remailers. "Subway" remailers would exchange identical sized "containers", much like a subway at semi-regular pulses or intervals. It would require a ring of remailers large enough (yeah, I know) to make traffic analysis of entrance and exit points difficult and/or expensive. Each container would contain either fixed or variable slots for multiple messages. Containers could be full, partially full, or even empty. (there would probably have to be a max message size) Subway remailers would be able to carry a message to a designated "last" remailer or to deliver blindly to a "last" remailer of random choosing. Messages may or may not change containers at the various stations/remailers. It could be randomized. Possible header scripts: X-Subway-Script: Ride 2; Latent: 03:30; Ride 3; Deliver; or many other possibilities. The whole container would be encrypted to the next remailer, giving the next remailer the same access to exchange passengers or to make them wait in a latent state. The quirkier matters on this are how to handle PGP so that nothing is compromised and for how the remailers to identify each other as "friendly and operational" so the subway system does not have a traffic jam. Crypto comments please. ------------------------------------------------------------------ P M Dierking |

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anon communication
by Harry S. Hawk 17 Dec '03

17 Dec '03

Re: anon communications Hello... There are many reason that anonymous communications are needed, I will just focus briefly on one that is important to our business. When we post jobs on the Internet we need to remain anonymous. We do this when we place ads in the NY Times as well. This is just one reason why anonymous communication on the Internet is very important. Harry Hawk Manager of Computer Services Warwick Baker & Fiore 212 941 4438 habs(a)warwick.com /hawk

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Re: Reordering, not Latency (Was: Re: Remailer)
by nobody＠replay.com 17 Dec '03

17 Dec '03

-----BEGIN PGP SIGNED MESSAGE----- On Wed, 25 Jan 1995 Michael Handler wrote: >On Wed, 25 Jan 1995 Louis Cypher wrote: > >> In recent discussions, the consensus >> was that message reordering was superior to (and the actual intent of) >> latency. Reordering is not sufficient, a form of latency is required >> to make it effective. > > I have literally hundreds of messages archived from the CP list of >several months back where Eric Hughes repeatedly states that reordering, >not latency, is the key. Reordering of a sufficient magnitude will >introduce latency inherently. Otherwise you are still vulnerable to >traffic analysis (which is an art, not a science, remember). > >-- >Michael Handler <grendel(a)netaxs.com> If you read my analysis with more care, you will note that I do not argue that latency is superior to reordering, nor that it should be used in place of reordering. Reordering is far superior to latency. My point is that pure reordering is vulnerable to attack. It is less vulnerable if combined with latency. Also note that this was a repost of a message I sent to the list some months ago. I sent it because it seemed similar to the work that Wei Dai has been posting. -Louis Cypher -----BEGIN PGP SIGNATURE----- Version: 2.6 iQCVAwUBLyiy0qyHUAO76TvRAQF6qAQAk6IDl+UknPQ+c6hbmPvlgCtF2xwG0KZ3 aUXiuv/XJ5e5prRwLQ4X6rOUSflT2f+mRPO4fveVmWePWcr8BtV6LUQM+qJOLe5k Ay7CD+OGN9ni9EhRbIg3Sgdv6yB8cX2CpdMSByFD8J9rM240UWqSt/DgNQIlkTtC Jx+0NQP80QA= =aKOE -----END PGP SIGNATURE-----

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Re: CERT statement
by cactus＠seabsd.hks.net 17 Dec '03

17 Dec '03

-----BEGIN PGP SIGNED MESSAGE----- - -----BEGIN PGP SIGNED MESSAGE----- In article <9501270023.AA17883(a)snark.imsi.com>, Perry E. Metzger <perry(a)imsi.com> wrote: >Well, sort of. A key management system that operates sort of like >Kerberos' is necessary. However, thats really far from >sufficient. Most Kerberized protocols authenticate only at the >beginning of the session -- very very hijackable. I just want to chime in that telnet{,d} clients are available that do encrypt every packet, built upon Kerberos v5 (and the GSSAPI) for key management. There are even libraries that sit on top of sockets with the same interface and do the encryption (and therefore the implicit authentication) of every packet. I'm sure Perry knew this, but I'm also sure others didn't. I'm afraid I don't have any pointers at the moment (though I know that they are in use in some parts of CMU), and unless your need is urgent and you already use kerberos you should just wait for the new swIPe. - - -- 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 - -----BEGIN PGP SIGNATURE----- Version: 2.6.2 iQCVAwUBLyh9zBNhgovrPB7dAQGk+gP/TatFUjwI79UT1UY5IQK82wlQ/jK7tOXb HX6zWCVU48l/vfAWHSYdS1QSQEeUMH4Z+lnW4lxW0G9fWDk/LxSlyJqnw/zDEbK+ 16ePq/6AWsCCA5Gt2HchAfVoC72iYOeU0oDMQJerr6K6s2FLZrR4vSEQAUSbkoJz VHLjcR6mrog= =JYyc - -----END PGP SIGNATURE----- - --- [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 iQBFAwUBLyi2nSoZzwIn1bdtAQFSiwGAspboooxRv7cVKp3/aPZGVaLkkscfSh/y PKrOIuBmAoaHmMwUGwV73ygYc3N1bvs0 =PKb8 -----END PGP SIGNATURE-----

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