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Was This the First Denial of Service Attack? 166

An anonymous reader writes "Way back in 1974, Dave Dennis, then aged 13, decided to try out the -ext- TUTOR command on the PLATO system at the University of Illinois, and see if he could cause all the terminals of other users to go offline. It worked. And he never got caught. Of course, the powers that be eventually caught on and fixed the -ext- command so terminals by default didn't automatically receive -ext-'s sent from other locations."
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Was This the First Denial of Service Attack?

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  • by TinBromide ( 921574 ) on Sunday February 14, 2010 @11:39PM (#31140318)
    • by Anonymous Coward on Monday February 15, 2010 @01:10AM (#31140896)

      This [] type of denial of service was already quite common long before that.

    • Re:Shorter answer (Score:5, Interesting)

      by A nonymous Coward ( 7548 ) on Monday February 15, 2010 @02:46AM (#31141330)


      I will back that up with my own story of a weaker DoS. The year was one of 1970-72, I do not know which. UC Berkeley had two CDC 6400s, A was normal, B was used for an experimental time sharing system and thus had an optional-at-extra-cost instruction, Exchange Jump, which swapped context. I had been toying with a Fortran program and gotten tired of it, so decided to finish it off in a burst of glory. It began execution in some obscure subroutine instead of MAIN, never called MAIN, and as it ground away at its nominal task, it gradually modified an innocent instruction into an Exchange Jump. But sadly, once it finally had modified it to the Exchange Jump opcode, there was no context, just a pointer to 0, and it farked the entire machine.

      Now I wasn't truly anti-social. I had in fact written on the card deck that it was only to be run on machine A, not B. Unbeknownst to me, that Exchange Jump instruction was also used by diagnostic programs, and the tech was too lazy to disable it after each visit, just left it enabled at all times, so my Fortran program crashed the machine.

      It wasn't much of a DoS, I will admit. The OS, CALIDOSCOPE (Cal Improved Design On SCOPE (Supervisory Control Of Program Execution)), could only handle 6 batch jobs at once at most, so that's the worst it could do. But I did get called in to the admin's office, who sighed and gave me that "What are we going to do with you?" look. He knew I wasn't malicious, but he had to warn me to not do it again.

      • Re: (Score:2, Interesting)

        by Anonymous Coward

        My own tale from 1974/5 was that my school had a time-sharing terminal and rented time from a local consulting company. Normally we used BASIC, but the maths teacher came back raving about the new language he had been taught at a weekend conference: APL. As one of the better pupils, I was given all the documentation, and went away to read up about it. A few weeks later, I had developed my symbolic differentiation program, and had carefully entered it in, and saved on paper tape. Unfortunately the program ha

      • No.

        100,000 BC

        "Krug, in next village, is giving away free Mammoth meat. Better hurry before it's all gone."

      • In 1979 I was a student at Virginia Commonwealth University, using their Hewlett-Packard 3000 Series III minicomputer system. I discovered that:

        -if you wrote a program called "A" which used the BASIC CHAIN statement to invoke a program called "B",
        -and if you wrote a program called "B" which used the BASIC CHAIN statement to invoke program "A",
        -and if you ran program "A" and waited about 30 seconds for the two programs to start ping-ponging back and forth between each other,
        -and if you then used the
    • Yes


  • by JorDan Clock ( 664877 ) <> on Sunday February 14, 2010 @11:39PM (#31140320)
    The first recorded denial of service was performed by a 13 year old, who was basically using a "script kiddie" technique? Well, color me surprised.
    • Re:Seems fitting (Score:5, Interesting)

      by EdZ ( 755139 ) on Sunday February 14, 2010 @11:48PM (#31140386)
      I'm not sure how this could be described as a "script kiddie" technique. The only pre-written software he used (exploited) was the 'ext' command itself. Unless you're expecting all 'real' crackers to only exploit programs and/or operating systems they've written themselves?

      Yes, yes, I know, Rule of Funny and all that. As a card-carrying pedant, it's a contractual obligation to bitch about this sort of thing.
    • Re: (Score:2, Offtopic)

      I think we should stop and give thanks to the author of the article for couching the story with "this is likely not the first DoS attack, but here's a neat story anyway."

      It's so refreshing to see Internet writers not making outlandish, unverifiable claims about things like this.

      So, props.
    • Re: (Score:2, Insightful)

      Surprised? How long have you been a /. member for? I've been a member for just a year and I already feel emasculated by all the kids who improve upon a technology before they stop wetting their beds.
  • by Anonymous Coward on Sunday February 14, 2010 @11:40PM (#31140326)

    And last post...

    -ext- :D

  • by Anonymous Coward

    You don't have permission to access /blog/2010/02/perhaps-the-first-denial-of-service-attack.html on this server.

    • Re: (Score:3, Informative)

      by scdeimos ( 632778 )

      I'm sure you're attempting to be funny, but for those actually interested in reading TFA...

  • by Darkness404 ( 1287218 ) on Sunday February 14, 2010 @11:45PM (#31140368)
    So, let me get this right. You could more or less get a list of addresses, and they would accept commands without question if you just typed in the commands and the right address? Sounds like the worst security system ever.
    • by Anonymous Coward on Sunday February 14, 2010 @11:51PM (#31140402)

      So, let me get this right. You could more or less get a list of addresses, and they would accept commands without question if you just typed in the commands and the right address? Sounds like the worst security system ever.

      Yeah, but this was 1974, when overly-trusting users used commands to do USEFUL things, rather than cause mischief (or shove adverts in front of you)!

      • by girlintraining ( 1395911 ) on Sunday February 14, 2010 @11:59PM (#31140456)

        Yeah, but this was 1974, when overly-trusting users used commands to do USEFUL things, rather than cause mischief (or shove adverts in front of you)!

        If you remember 1974, you weren't there, maaan!

      • I dont care if its 1974 ot 1794, human nature doesnt change. Put locks on your (virtual) doors.

        • Re: (Score:2, Insightful)

          From the summary:

          And he never got caught.

          If he did get caught he'd get a smirky, eye-rolling verbal warning instructing him to stay away from the terminal. Nowdays a kid would be taken into custody and charged with violating computer crime and terrorism laws.

          FBI and/or DHS interrogations would follow, then he'd be forced to turn snitch and lure other kids(er, "marks") into "hacking" the system, to avoid a decade or more of federal prison.

          • Re: (Score:3, Interesting)

            by Bert64 ( 520050 )

            When i was in school (age 6), we had a single computer in the whole school which ran a selection of very simple programs, one of which simulated a snooker table and calculated how many times a ball would bounce before falling down a corner pocket. You had to enter the width/height of the table and guess how many bounces...
            I entered a size of 0 for the table, and the program promptly crashed.. The teacher saw, called my actions stupid and sent me to the headmaster, who promptly banned me from ever touching a

            • by Kjella ( 173770 )

              When i was in school (age 6), (...) The teacher saw, called my actions stupid and sent me to the headmaster, who promptly banned me from ever touching a computer again so long as i was at that school.

              Somehow, this picture from the US of six year olds in hand cuffs comes to mind. That reaction is just fucked up in so many ways.

            • The teacher saw, called my actions stupid

              And what did this teacher think of the programmer's not allowing for (or preventing) someone entering a value of zero?

        • by PCM2 ( 4486 ) on Monday February 15, 2010 @12:59AM (#31140840) Homepage

          I dont care if its 1974 ot 1794, human nature doesnt change. Put locks on your (virtual) doors.

          Yeah, that seems like great advice now, but hindsight is always 20/20, as they say. As recently as the early 90s, most Unix systems didn't even use shadow passwords.

          Admin Guy: "Yeah, so what could happen? Some college kid is going to buy a Unix server and set it up in his dorm room so he can run a brute force attack on /etc/passwd? I'd like to see that one!" LOLZ, snort snort...

          • by mysidia ( 191772 ) on Monday February 15, 2010 @03:03AM (#31141458)

            They were crypted... why would you need to hide a strong password that was crypted? Shadow'ed passwords are an ugly hack.

            Also, if you restrict "shadow" passwords so only root can see them, then suddenly every program that needs to perform authentication must be setuid root...... this is a security risk. In that era, possibly a much larger security risk than the risk of a strong password being cracked.

            The problem wasn't failing to use shadow passwords. It was (1) UNIX users who set weak passwords, and (later), an (2) explosion in computing power, making it easier to attempt to crack the passwords.

            Also, the reverse-engineering of the original DES-based crypt binaries allowed inefficiency that was intentionally contained in the algorithm to slow it down (making use for cracking improbable), to be removed, after years of study.

            The DES-based crypt() algorithm was optimized into fast-crypt which was orders of magnitude faster, and actually made password cracking feasible. If a harder cryptographic algorithm would have been used -- then matters could be very different.

            The latter bit they should have seen coming. The explosion in computing power was by no means a certain development, it wasn't an immediate issue at the time.

          • >Yeah, that seems like great advice now, but hindsight is always 20/20, as they say. As recently as the early 90s, most Unix systems didn't even use shadow passwords.

            Yet in 1993, Windows NT had ACLs, security groups, NTLM, etc. Theres no excuse for ignoring basic security principles. CS departments and tech companies the world over have understood these basic controls since the 50s or 60s.

            Sadly, everyone has to reinvent the wheel. Look at how PHP has changed from "personal home page" which was a security

      • Exactly (Score:4, Interesting)

        by NotQuiteReal ( 608241 ) on Monday February 15, 2010 @01:03AM (#31140866) Journal
        I don't think it was quite as early as 1974, but somewhere right around there, I remember going to the "math room" in Jr High, and being able to access a terminal to get to "the main frame". It was something that used fan-fold paper (not a CRT). You could write BASIC programs on it, I think. I kind of remember writing stuff as complicated as 2D grid based Star-Trek type programs (one step up from Hunt the Wumpus).

        Anyhow, we did have a command that we could type in that would crash the system, which we did once in a while, just to cause mischief. I really don't recall if we discovered it, or it was given to us (a la script kiddie), but it eventually ended up being a program called "runme" or some such...

        Anyhow, letting random people on a "public" terminal to the mainframe of the San Diego unified school district is probably a thing of the past.

        The best security breach, by far, however was an attempt to save money by re-using the fan-fold computer paper. Man, there was some juicy stuff on the flip-side of that stuff - names, addresses and IQ rating of all your class mates, payroll runs, all sorts of entertainment!

        Simpler Times. Get off my lawn!
      • Hey you're not asking me to go back in time to deny this kid's god-given right to his first ever DoS, that would be like Denying a DoS....

    • Re: (Score:1, Interesting)

      Sounds like the worst security system ever.

      *cough* Diebold. *cough*

    • by pookemon ( 909195 ) on Monday February 15, 2010 @12:00AM (#31140466) Homepage
      So I'm guessing you weren't around in 1974. It might also surprise you to learn that once upon a time there were no virus scanners or firewalls. I bet I just blew your mind with that one...
      • Another thing about PLATO in particular, is that while it was very cool and ahead of its time, there was very little important secret information stored in it.

        Most of the users used it to do mundane homework assignments. It also had some games, and facilities that resembled today's newsgroups, chat and rudimentary informational websites.

        At least in the site I used, keeping the aging Control Data Cyber mainframes that hosted PLATO creaking along was probably a much bigger worry than any security threats. Th

    • Re: (Score:3, Interesting)

      You know, this was all way before my time, but back then, security was not a common concern on university computers. People working in a lab trusted each other; thus, those who used Unix (or a similar system) would leave their home directories world readable, and as another example, ITS had the ability to observe another user's keystrokes. Things changed in the 1980s as more students got computer access and as proprietary software became the norm.

      There are still echoes of the trust that existed back th
      • nd the permissions on home directories are 755 by default.

        thats actually common on a lot of unixes(OS X for example), and not really as bad as you think it is. Essentially it just allows any users to get a list of files on the top level of the home directory, thats it. You cannot necessarily even read any files in the root of the home directory, just list their names and sizes. The really important thing is what their default umask is set to be. Any decently good paranoid cs student will set it to 0
        • Actually, I'd expect a paranoid CS student would be setting the umask [] to 0077. If you're that paranoid ... do you really want other group members (students) reading your code? (Ah, the days when the student server was Hardy and the Staff one Laurel ... 500 CS students compiling at the same time on a <60MHz SuperSPARC I was NOT FUN, and those of us who tutored used the staff server instead. Same spec, 3x as fast!)

          And since you can't get a umask right, you can hand in your geek card on the way out the door

      • And the fact that you need to SSH in with your own credentials mean that if you were stupid enough to do something of the sort, they'd haul your ass over the coals.

        If you're dealing with people in positions of trust, logging is often the right balance between security and trust. It doesn't stop them from doing the things they need to, but the knowledge that their fingerprints will give them away will (generally) stop them from doing anything to violate that trust.
      • I used the Multics system in 1971, and permissions were in place and used. Not long after the system was first brought up, a friend of mine who was a developer but not totally aware of what everything did, found some files he had full access to that he didn't recognize. So he erased them and the system crashed. The next day, did the same thing. Turns out that he had erased the OS. The next time the system was brought up, the permissions were corrected to prevent general user write access to the OS.
    • Re: (Score:3, Insightful)

      by Sycraft-fu ( 314770 )

      Computer security was poor back in the day. Since computers were expensive, scarce things that were generally not connected to others, it wasn't a big deal. You knew everyone who had access, if someone caused trouble they'd get in trouble. Even once the Internet, or rather ARPANET back then got started, security was extremely lax. If you look at some of the low numbered ports you'll discover they ware things like "chargen" which just sends a random string of characters out. You can see how this would be a b

    • Security? When I first sat down at a PLATO IV terminal in Jan 1973, you typed "s" to login as a student, and "a" to login in as an author -- no passwords. If you could guess a file name (called "lesson spaces") you could edit it. Al McNeil and I found any number of allocated-but-unused lesson spaces and just started poking and prodding the system. Al and I basically "guessed" the TUTOR language from looking at other people's code because there were no manuals available at that time (at least not in far off

    • So, let me get this right. You could more or less get a list of addresses, and they would accept commands without question if you just typed in the commands and the right address? Sounds like the worst security system ever.

      In UNIX systems, circa 1997 and before, they'd allow anyone to write to any TTY. This was how Talk worked, for instance.

      So when I wanted to mess with my friends, I'd cat poetry or /dev/random > their TTY and watch them start cursing in the lab.

      It's how I taught my friends about ^L.

  • I always think of DoS meaning flooding a system with requests, causing all resources to be used, thus nobody can get service.

    It seems like this guy just found a "Halt and Catch Fire" instruction and an overly trusting security policy. Which may have been a first something, but not really a DoS, right? Or am I missing something?

    • Re: (Score:3, Informative)

      by XanC ( 644172 )

      A DoS, generally, is anything that prevents a computer (or I suppose anything) from performing its functions. It's anything that "denies" "service".

    • by nedlohs ( 1335013 ) on Monday February 15, 2010 @12:03AM (#31140492)

      "Denial of Service". It's the damn name.

      One way is to flood the system, but there are plenty of other ways. The one mentioned for example.

    • by Fallon ( 33975 ) <> on Monday February 15, 2010 @12:04AM (#31140506) Homepage Journal
      What does DoS stand for? Denial of Service. Getting everybody kicked off the system certainly sounds like denying them access to that computer service to me. Just because a DoS is usually performed by a network flood of some kind doesn't mean that's the only way to do it. Heck an idiot tripping over the power cord to the server is technically a DoS if people loose access.
      • by Rennt ( 582550 )

        Heck an idiot tripping over the power cord to the server is technically a DoS if people loose access.

        PRACTICALLY. That would practically be a DoS. Technically all you've got is a clumsy buffoon.

        Anyway, nobody ever means "denial of service" when they say DoS. It is a "denial of service attack". Which def. does not include unplugging the server.

        • by Sique ( 173459 )

          Hm. I never thought DoS attacks would be limited to saturating the requested resource. I always understood that intentionally denying access to the resource in a malicious way was the DoS attack.

      • By that definition, walking up to their terminal and hitting it repeatedly with a baseball bat would also be a denial of service attack. So would physically restraining them in their chair such that they were unable to reach the keyboard.

        This seems to me to be an overly broad definition. The term "denial of service attack" has taken on a more specific meaning than "any means of denying access to a computer system".

    • by xous ( 1009057 )


      DoS stands for 'Denial of Service' so anything that can cause a system to fail to respond to legitimate requests.

      • But usually a DoS is about preventing the server from responding to a request from any client. It sounds like he hacked the clients... all of them. I'm sure it was fun, but is that a DoS? A client with better security would not have been affected.

        • by xous ( 1009057 )

          If you consider the service "access to a terminal" and the client the user the term holds.

          There are also local DoS exploits that don't require network connections so I'm fairly sure this holds as well.

    • by cvd6262 ( 180823 ) on Monday February 15, 2010 @12:16AM (#31140598)

      Back in the 19th Century (in the US anyway), mail *recipients* paid postage to get their mail from the local general store. Political figures and others who might have a negative following would receive scores of blank letters and have to pay for them. The objective was to either crowd out the legitimate communications or bankrupt the recipient. Traditionally, one could place an ad in the local paper explaining that he or she would no longer receive letters at the store, which would free them from their obligation.

      • by Cryacin ( 657549 )
        I have the feeling that back in the 19th Century (in the US anyway) people like that would be having an abrupt and Frank discussion with Mr. Colt. Especially in the wild west. ;)
        • The post-Civil War West was very rarely the kind of lawless anarchy that Hollywood portrays. There were a few specific times and places where it was, but those trouble spots got cleaned up pretty quickly. People don't like living with bullets flying randomly around their heads.

          The early 19th c. frontier (which in those days was mostly east of the Mississippi) on the other hand ... yeah. But that was before "Sam Colt made them that way." Most of the killing was done with single-shot firearms or, very oft

      • Another similar trick I heard was to order a lot of large, cheap things in boxes and send them to a competitor, thus jamming up their supply line (they had all this stuff stuck on the unloading area and no place to put it). I'm not sure how often this was done, but someone must have done it.
    • Re: (Score:3, Informative)

      by weicco ( 645927 )

      Flooding is just one way/method to execute (D)DoS attack. You can read more here: []

    • Re: (Score:3, Interesting)

      by tricorn ( 199664 )

      Well, the -ext- command was used to send data to an arbitrary piece of "external" equipment attached to the terminal. A couple devices were a 4-voice music synthesizer, a Votrax voice synthesizer, and a random-access audio play-back device.

      It was useful with some of the equipment for another user's program to be able to send such external data to your equipment and vice versa. Most people didn't have anything attached, but the system didn't know that. With nothing attached, all it did was make your termi

  • One of many ways... (Score:4, Interesting)

    by mikael ( 484 ) on Monday February 15, 2010 @12:01AM (#31140474)

    It used to be possible to crash early Sun servers (or at least the terminal server attached to the server by trying to copy data from a virtual terminal (cat /dev/ttyp0) or something similar.

    One university department tried to get around the user quotas on commercial UNIX licenses by creating a single user account for an entire class. Hilarity ensued as students working on real-time projects would accidently kill each others processess.

  • 2 minutes searching shows - October 29, 1969

    First packets sent by Charley Kline at UCLA as he tried logging into SRI. The first attempt resulted in the system crashing as the letter G of LOGIN was entered.

    I'd bet that part of the initial DARPA deployment testing involved deliberate attempts to jam the network

    Just saying....

    • by tricorn ( 199664 )

      I really don't think Charley was trying to crash it, so it wasn't a "denial of service" attack. In fact, there was no service, so nothing was being denied! All these stories of "well, I typed this and it crashed the system" aren't DOS attacks. Deliberately doing it repeatedly, and in a way that couldn't be easily locked out (e.g. by deleting your user account and banning you from the computer room) might constitute a DOS attack, but there has to be an intent to Deny Service to one or more other people.

  • by chelberg ( 1712998 ) on Monday February 15, 2010 @12:35AM (#31140718)

    In high school in 1974 our district (8 schools) used an HP access timesharing system. It ran the BASIC language. I was able to write a very short program that would cause the system to crash. Having discovered this bug in the system, I was able to bring down the entire district's computers at will. I had discovered this capability while exploring a new feature of BASIC. Fortunately for them, I was ethical and informed my teacher who at first didn't believe the exploit until I demonstrated it in front of her. We then contacted HP, gave them the code, and they came up with a patch within a couple of months. I'm not sure if anyone at HP can confirm this at this point.

    I am sure that there are probably earlier exploits as well.

    And as a side note, I was also a PLATO author in 1975 and greatly enjoyed working on that system.

    • In high school in 1974 our district (8 schools) used an HP access timesharing system. It ran the BASIC language.

      I suspect that by modern standards it would be more accurate to say that it walkedBASIC.

  • by DougReed ( 102865 ) on Monday February 15, 2010 @12:43AM (#31140756)

    The earliest one I know of was by the smartest man I ever knew (and the strangest). He was my mentor. In the IBM 360 days this guy used to write code .. COMPLEX code in binary on the roller bars on the front of the console because he was too lazy to logon. He made IBM's code more efficient by eliminating all modularization. It was more efficient to just have one big super efficient kernel, so he redesigned their system, and got something like 140% efficiency out of the hardware (40% greater than theoretical possibility) by IBM's own benchmarks, and found a security hole in their code in the process .. as he put it "bit enough to drive an 18 wheeler through", which he reported to them. They told him it was his hacking, he broke something ... NOT OUR CODE!!! IBM CODE CAN'T BE BROKEN!!! So he went to their 'demo center' and fed in a deck of punch cards.

    On the IBM Selectric console in the IBM demo center, it printed.

    "May I please have a cookie?"

    The operator ignored it.

    8 hours later during shift turnover It printed

    "I never got my cookie"

    The two operators looked at it, shrugged, and ignored it. The dayshift operator went home.

    4 hours later the console printed.

    "You're not a very nice operator either, I never did get my cookie"

    The operator thought the guys upstairs were fooling around and ignored it.

    2 hours later.



    1 hour later.

    "Dammit give me a cookie!"

    30 minutes.


    15 minutes ... 7.5 minutes ... eventually we get to 32 cookies this second .. 64 cookies this second ... 128 cookies this second.

    An IBM Selectric typewriter which is the main console for a 360/65 cannot print even the word cookie in a second, much less a whole sentence, and certainly not 128 of them! There was ONE way to crash a 360/65 .. Fill up the console buffer. The system considered console messages to be important, and if the system couldn't print all of them, it halted.

    Reboot ... excuse me... Mainframe terminology here... "IPL" the system. First console message:

    "You know, I never DIID get my cookie!" .. and the process starts over.

    Finally IBM called my mentor...

    um... did you submit a job to the demo center?

    Yes, but don't worry, it was just a simple 'unprivileged' process, and as you said, your security is flawless, so I am sure there is no danger. :-)

    Sir, I think we are prepared to acknowledge that there MAY BE a security hole in our system somewhere. It seems that your job never finished and yet it does not seem to exist in the system anywhere. Our experts tell us we have to re-install the operating system to fix it. Do you have any alternative suggestions?

    Just one... Go get the best operator you have and put him on the console and call me back.

    Yes sir... .. an hour later

    Sir, this is king super operator, they just called me back in to work to assist you in solving our issue.

    OK ... now listen carefully. I am only going to say this once. Type carefully, and don't screw this up .. are you ready?

    Yes sir.

    Good type this ... "c" "o" "o" "k" "i" "e" ... now press "Enter"

    Console prints . "Thank you that was good", and the job ends.

    After that IBM never ever questioned it if my mentor reported a problem with IBM software ever again.

  • by dmomo ( 256005 ) on Monday February 15, 2010 @12:43AM (#31140762)

    Denial of Service is just about as old as marriage.

  • Back in my high school's UNIX system I used to like piping binary files to people terminals. It worked pretty well as a DoS and made a loud racket with the all the BEL characters.

    Cntl-S could also be used to halt people's sessions, and "+++" would screw with people on dial up sessions.

    The good ol' days.

  • Yes, of course. 13 years old kids in 1974 got access to UI computer systems without paying for timeshare.
    Our hero, managed to take a whole room of "terminals" offline with one existing command.

    And now [queue evil music] 36 years later, having done nothing of note ever, he now seeks his hard-earned fame.

    First ever DoS... or 49 year old sociopath longing for publicity... or just a liar. You decide. I already have.


    • Yes, of course. 13 years old kids in 1974 got access to UI computer systems without paying for timeshare.

      Yeah, there's no way UI would show some kid favoritism [].

  • by Space cowboy ( 13680 ) * on Monday February 15, 2010 @01:01AM (#31140858) Journal
    See This journal entry [] I posted a while back... These days, at least in the US, I'd probably be up on federal wiretap charges or something. Back then, it was serious enough that they'd threaten to throw me out of college, but I never got any sense of there being jail-time involved...

  • Well if that was the first DOS, then I'll claim the first "Slashdotted" on a PLATO system. In 1987 after the local admins cut off all access to chat ( due to abuse of the system by people sitting next to each other using "chat" ) I wrote a tutor script that caused a timeout error every second.

    The result was to flush the keyboard buffer to common memory. Then the other terminals read the common memory and updated their display - Kind of like early IRC. Because this was written at the lowest security level, t

    • Law of unintended consequences - they cut off chat for something pretty minor (using chat when sitting next to each other - that's "abuse"?) and created a much bigger problem.

    • You use a lot of words, but they don't really make sense when put together. A "tutor script"? A timeout error every second that flushes the keyboard buffer to common?

      The common "chat" program was talkomatic ("talk" on Unix systems is very similar, it allowed up to 6 people to communicate at once, with any number of additional people to monitor a channel), and it really wouldn't matter if everyone on the system was in it, it was fairly efficient, so I don't know why they'd want to prevent people from using

  • by Kenja ( 541830 ) on Monday February 15, 2010 @01:53AM (#31141112)
    Taking out telegraph lines, signal towers, killing messengers. DoS attacks have existed as long as people have tried to communicate over distances. Even man in the middle attacks, intercepting and replacing semaphore messages etc.
    • Absolutely. there probably were some earlier purely logic based attacks on phone systems.

      For example in Germany you could for a long time just call somebody and not hang up. Only the originating party could stop a phone call, so the other party did have their phone disabled. Some taxi companies used that to play foul on their competitors.

  • My first DoS discovery was in October 1976. On IBM mainframes running VM/CMS, I found I could take down the entire system from an ASCII serial port connection, without even being logged in. At any prompt, including the "LOGON:" prompt (hence why being logged in was not needed), just press the RETURN key followed immediately by the BREAK key.

    A couple years later when I obtained the source code to the system (bought it on a reel of tape, from IBM, for $150) I found the bug in the code that caused it. The "CP"

  • In 1972, I was a college student with more time on my hands than sense. Here's a few things I did to a $4 million CDC 6600 time-sharing system:

    (1) Hells bells: This machine had ten PP's (Peripheral Processors) that offloaded I/O tasks. The PP's had for-the-time screaming I/O speeds-- all of 2MBPS. User disk space consisted of two washing-machine sized disk drives, 88MB total. A little metal arithmetic suggested that you could fill the disks in no time. so a 2-line FORTRAN program: 1 WRITE(1) 764

    • (3) On early core RAM modules, the modules were interleaved 8-wise, so each module only got accessed every 8-th word fetch.. But if you knew this, and wrote a program that jumped forward 8 words several dozen times, then jumped back to the start, one module would get accessed at the maximum possible rate and within a minute the module would melt down. I did not try this ( the 4K modules must have cost $100 or so ), but I heard of someone that did.

      Purdue's CDC 6000 series machines had a similar bug that would destroy modules. (I still have a pair) AFAIK, they cost much, much more than $100 each. They were core modules that had 48k by 1 bit and had been assembled by hand.

      The CDC was retired with a major security bug. The system "root" password was stored in a protected place in memory, but the core dump routine didn't honor the memory protection. You would load an address register with the location of the root password, then trigger a core du

      • > (I still have a pair) AFAIK, they cost much, much more than $100 each. They were core modules that had 48k by 1 bit and had been assembled by hand.

        Yes, I meant to say, more than $1000 in 1972 dollars.

        And yes, there were many ways to get passwords-- the simplest being to run the password changing program from one terminal and dump out memory from another. At first when you requested memory the OS did not zero it out! Easy password pickins.

        For a long while the password file was passed form system to

  • The author and I were contemporaries and he forgot one very important reason he was never prosecuted. In 1974, there was no crime even if this had been done by an adult maliciously and for money. The pendulum, of course, has swung far in the other direction and users now face serious criminal charges for TOS violations.

    By the way, many of us who have good heads for computer security learned during years before it became a felony to practice.
  • Quoting David Woolley []:

    Reminds me of something I did on PLATO III. Back then, the -press- command let you give an argument to cause a keypress at another terminal. Naturally, the 16-year-old mind wonders what will happen if you put all the terminals in the classroom into a chain where a keypress on one ripples through them all and cycles back around to the original. Well, it hangs the system, that's what.

    I actually remember being there when the -ext- command exploit hit. It didn't hit me personally but it

    • I never knew of a -press- command variant that allowed you to press keys on someone else's terminal, although that would be a logical way for the screen-sharing term-whatever that was to work.

      The -ext- command was particularly hilarious if the terminal had that rube-goldberg microfiche slide projector. It was literally steam-powered through a pneumatic line. Well, air, not steam, but awfully close. You could step the 8x8 michrofiche and make the terminal wobble.

      • by Baldrson ( 78598 ) *

        You could step the 8x8 michrofiche and make the terminal wobble.

        IIRC that was called "washing machine mode" by some, due to its resemblance to an unbalanced spin-dry cycle.

    • by Baldrson ( 78598 ) *
      Erratum: David Woolley's quote should have ended with "that's what."

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