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TUCoPS :: Web :: Servers :: javapwsd.txt

Java Personal Webserver 0.9 Denial of Service





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::     .ooO Java Personal Webserver 0.9 Denial of Service by wyze1 Ooo.     ::
::--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--::
::                                                                          ::
:: The Java Personal Webserver 0.9 by Clay Lenhart (Available from Tucows)  ::
:: is a freeware webserver written entirely in Java. It features on-screen  ::
:: logging and implements only the GET and HEAD functions. (HTTP 0.9)       ::
::                                                                          ::
:: This bug was tested on a Windows 98 box with JDK 1.1.1 and it worked     ::
:: fine. I was going to test it on another Win98 box with JDK 1.2.1, but    ::
:: the fucking program decided to break - (The author hasn't ported it to   ::
:: Java 1.2 yet). It has not been tested on a Unix box because we refuse to ::
:: run Japan's Secret Weapon, aka. XFree86 on any box we wouldn't want      ::
:: Satan to posses. If some-one else wants to test it and tell us what      ::
:: happens, feel free.                                                      ::
::                                                                          ::
:: Okay, so whats the problem? By connecting and typing GET followed by a   ::
:: couple of thousand characters (3000 for every 32mb of RAM on the system  ::
:: sounds about right) the system will become low on memory and the Java    ::
:: Virtual Machine will start whining about stuff like..                    ::
::                                                                          ::
:: java.lang.OutOfMemoryError: <== Type of error that occurs when           ::
::         at ConnectionThread.readCommands(wyze1.java:521) <== Reading GET ::
::         at ConnectionThread.run(wyze1.java:344) <== And Executing GET    ::
::                                                                          ::
:: Right, so the VM has decided the system is low on memory. Thus the VM    ::
:: Garbage Collector will run on a thread with full priority. Okay, a bit   ::
:: of background for non-Java coders is required: Unlike other languages,   ::
:: you don't have to kill objects once you are finished with them, the      ::
:: Garbage Collector does it for you when there are no further references   ::
:: to the object. The GC can be called manually, and will also run          ::
:: automatically when it feels like it, and with full priority if the       ::
:: system is low on memory - like it is now. ;)                             ::
::                                                                          ::
:: So, the Garbage Collector looks around for threads to kill, and alas, it ::
:: can't find any, so it just stops anything more being written to the      ::
:: editable textbox in the centre of the window, regardless of the fact     ::
:: that thats where our logging would be if it still worked. =P             ::
::                                                                          ::
:: Fixing the error should be fairly simple - the only reason I didn't do   ::
:: it myself is because that would require porting the app to Java 1.2 and  ::
:: that is just TOO much work. ;) However, should the app be ported to Java ::
:: 1.2, the bug could be fixed by using JFC/Swing instead of AWT and        ::
:: making the Textbox a Label. Then, the user input should be limited to    ::
:: a certain number of characters, and errors caused by too many chars in   ::
:: the user input should be catched.                                        ::
::                                                                          ::
:: You will find the exploit for this vulnerability in the lame-java-c0de   ::
:: directory of this issue if you want. Have fun!                           ::
::                                                                          ::
::                               --=====--                                  ::
::                    <wyze1> g1bb0r mE s1bb0rs3ckz                         ::
::                        <Eth`Real> Okay. *uNf*                            ::
::                              <wyze1> ta                                  ::
::                               --=====--                                  ::
::                                                                          ::
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