Java Class support

The upcoming 0.9.0 version of the Profiler adds support for Java class files. This will be especially useful for malware analysis. The support includes: disassembler, format views and layout ranges. Let’s see some screeshots of the format itself first.

Here’s a view of the constants:

Note: Utf8 strings are highlighted in orange just to distinguish them.

Here’s a view of the methods with their attributes:

And here’s the layout ranges view:

Again strings are in orange, while the actual code of a method is in a slightly lighter green than the method itself.

Since the format of class files is contiguous, it’s extremely easy to use layout ranges to create a new custom class file using the hex editor.

And finally, the disassembler:

The output shown in the screenshot above:

// SourceFile: HelloWorld.java
 
super class HelloWorld extends java.lang.Object
{
 
  static float f1;
  public static java.lang.String hello;
 
  HelloWorld()
  {
    // max_stack = 1  max_locals = 1
// line 1
    aload_0
    invokespecial java.lang.Object.<init>() // returns void
    return
  }
 
  public static void main(java.lang.String[])
  {
    // max_stack = 7  max_locals = 6
// line 7
    ldc2_w 454.546
    dstore_1
// line 8
    ldc2_w 552441554577111995
    lstore_3
// line 9
    getstatic java.lang.System.out // java.io.PrintStream
    ldc "The value of i is: %f and %d"
    iconst_2
    anewarray java.lang.Object
    dup
    iconst_0
    getstatic HelloWorld.f1 // float
    invokestatic java.lang.Float.valueOf(float) // returns java.lang.Float
    aastore
    dup
    iconst_1
    lload_3
    invokestatic java.lang.Long.valueOf(long) // returns java.lang.Long
    aastore
    invokevirtual java.io.PrintStream.format(java.lang.Stringjava.lang.Object[]) // returns java.io.PrintStream
    pop
// line 10
    getstatic java.lang.System.out // java.io.PrintStream
    getstatic HelloWorld.hello // java.lang.String
    invokevirtual java.io.PrintStream.println(java.lang.String) // returns void
// line 13
    try
    {
      getstatic java.lang.System.out // java.io.PrintStream
      ldc "test2"
      invokevirtual java.io.PrintStream.println(java.lang.String) // returns void
    }
    catch (java.lang.Exception)  goto loc_57
// line 18
    goto loc_67
// line 15
loc_57:
    astore 5
// line 17
    getstatic java.lang.System.out // java.io.PrintStream
    ldc "error"
    invokevirtual java.io.PrintStream.println(java.lang.String) // returns void
// line 19
loc_67:
    return
  }
 
  static void <clinit>()
  {
    // max_stack = 1  max_locals = 0
// line 3
    ldc 43
    putstatic HelloWorld.f1 // float
// line 4
    ldc "Hello world!"
    putstatic HelloWorld.hello // java.lang.String
    return
  }
 
}

And the original source file:

class HelloWorld
{
  static float f1 = 43;
  public static String hello = "Hello world!";
  public static void main(String[] args)
  {
    double d1 = 454.545774;
    long l1 = 552441554577111995L;
    System.out.format("The value of i is: %f and %d", f1, l1);
    System.out.println(hello);
    try
    {
      System.out.println("test2");
    }
    catch (Exception e)
    {
      System.out.println("error");
    }
  }
}

There’s yet more to come. Stay tuned. :)

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