Igor’s tip of the week #90: Suspicious operand limits

Although in general case the problem of correct disassembly is unsolvable, in practice it can get pretty close. IDA uses various heuristics to improve the disassembly and make it more readable, such as converting numerical values to offsets when it “looks plausible”. However, this is not always reliable or successful and it may miss some. […]

Igor’s tip of the week #89: En masse operations

Last time we used operand types to make a function more readable and understand its behavior better. Converting operands one by one is fine if you need to do it a few times, but can quickly get tedious if you need to do it for a long piece of code. En masse operation To convert operands of […]

Igor’s tip of the week #87: Function chunks and the decompiler

We’ve covered function chunks last week and today we’ll show an example of how to use them in practice to handle a common compiler optimization.   Shared function tail optimization When working with some ARM firmware, you may sometimes run into the following situation: We have decompilation of sub_8098C which ends with a strange JUMPOUT statement and if […]

Igor’s tip of the week #86: Function chunks

In IDA, function is a sequence of instructions grouped together. Usually it corresponds to a high-level function or subroutine: it can be called from other places in the program, usually using a dedicated processor instruction; it has an entry and one or more exits (instruction(s) which return to the caller); it can accept arguments (in registers or […]

Igor’s tip of the week #84: Array indexes

We’ve covered arrays previously, but one feature briefly mentioned there is worth a separate highlight. Complex programs may use arrays of data, either of items such as integers or floats, or of complex items such as structures. When the arrays are small, it’s not too difficult to make sense of them, but what to do […]

Igor’s tip of the week #83: Decompiler options: default radix

We’ve covered the major pseudocode formatting options previously but there is one more option which can influence the output. It is the radix used for printing numbers in the pseudocode. In a positional numeral system, the radix or base is the number of unique digits, including the digit zero, used to represent numbers. For example, for […]

Igor’s tip of the week #82: Decompiler options: pseudocode formatting

The default output of the Hex-Rays decompiler tries to strike a balance between conciseness and readability. However, everyone has different preferences so it offers a few options to control the layout and formatting of the pseudocode. Accessing the options Because of its origins as a third-party plugin for IDA, the decompiler options are accessible not through IDA’s […]

Igor’s tip of the week #81: Database notepad

There are multiple ways of annotating IDA databases: renaming, commenting, or adding bookmarks. However, sometimes there is a need for general notes for the database as a whole, not tied to specific locations. Notepad window The database notepad is a text input box which can store arbitrary text within the database, so you can add […]