How do I create the following solid body using Catia surfacing tools only?

For all it is worth, all CAD software's available are capable of producing this simple part. It is all about drawing sketches and applying extrusions with fillets. Try it using your software.

As Carlos said, this is a fairly simple part to model in CATIA as a solid. Using just the surface tools, this part becomes difficult and very time-consuming, with no added benefit. Other than a training exercise, why would you want to do this?

To model this using surface techniques involves the following steps:
(Using the GSD workbench and with minimal use of Sketches)
1. using the POINT, LINE, and CIRCLE tools, draw as many of the edges of the part as possible.
2. add some PLANES and use the PROJECTION tools as a quicker/easier way to draw more edges.
3. curved faces are typically made with REVOLVE or MULTI-SECTION SURFACE tools. INTERSECT surfaces with planes or other surface to draw more complex edges. SPLIT commands can also be used to trim back surfaces and get more edges.
4. after all the edges are drawn, FILL can be used to add surfaces where there are flat faces. Multi-SECTION SIURFACES can be used also.
5. JOIN all the surfaces together when done. If you can MEASURE the inertia of the Join, you have a complete Boundary-rep model of your part

you asked: "how do I create a counterbore hole in angle using the surfacing techniques only?

One way is the make a plane based on one of the angles of the axis of the C-bore hole. Then make a sketch of the hole profile with an axis at the other angle. REVOLVE the sketch to get the c'bore hole surface and trim the edges.

If I had to guess, the holes and the cutout on the corner would require some form of boolean operation. Create a cylinder with the specified radius and use it as the boolean operation's cutoff form. More information about this blog may be found here—>
http://abdulsguide.com/