On this weblog collection, I can be placing the highlight on helpful Ghidra options you might have missed. Every submit will have a look at a special characteristic and present the way it helps you save time and be more practical in your reverse engineering workflows. Ghidra is an extremely highly effective software, however a lot of this energy comes from understanding the best way to use it successfully.
On this submit, I can be discussing what slice highlighting is and the way it helps us visualize relationships between variables to raised perceive a program. Earlier than we are able to focus on the best way to use slice highlighting in Ghidra, I’d wish to take a second to introduce the idea of program slicing. By way of software program reverse engineering, program slicing is a means of abstracting code into smaller teams of statements often called slices. Slices are shaped by following how a selected variable’s worth impacts or is affected by the values of different variables. The Ghidra Decompiler exposes performance to shortly apply highlighting to visualise these program slices.
The simplest strategy to entry slice highlighting inside Ghidra is to right-click on a variable within the Decompiler:
You will need to be aware that the slice highlighting choices are solely out there when the cursor is at a variable whose worth is getting used or set. Slice highlighting shouldn’t be out there within the context menu if the cursor is at a variable declaration or a program level the place the handle of operator (&) is getting used. The Spotlight Ahead Slice motion will spotlight variables whose values are affected by the worth of the variable underneath the cursor.
Within the above instance, a ahead slice was requested for index on line 31. Observe that on line 31, the utilization of floor_area wouldn’t be affected by index till after the loop restarts.
Spotlight Backward Slice will spotlight variables whose values contributed to the worth of the variable underneath the cursor.
Within the above instance, a backward slice was requested for index on line 31. The one highlighted variable on this case is index, and it consists of the initialization of index previous to coming into the loop.
Along with these choices, Ghidra additionally has ahead and backward ‘Inst Slice’ choices. That is quick for instruction slice and can embody all directions that have an effect on or are affected by the worth of the variable underneath the cursor.
Within the context of vulnerability analysis, slice highlighting gives a strategy to shortly establish the scope of management an attacker has once they management a selected variable or alternatively which variables they would wish to manage to affect the worth of a variable.
Learn Extra about Ghidra
Ghidra 101: Cursor Textual content Highlighting