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Difference between revisions of "HOWTO-Reverse Engineering"
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Fixed search strings in file access section
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=== File Access === | === File Access === | ||
One of the easiest places to start a disassembly is generally by identifying file accesses. Using IDA, you can, for example, do a text search for 'open | One of the easiest places to start a disassembly is generally by identifying file accesses. Using IDA, you can, for example, do a text search for 'open', 'read', 'close', etc. to find occurrences of file opening. IDA provides standard comments for many operating system calls, so even in a new disassembly you should be able to locate such calls by their comment text. Likewise for file reading, writing, and closing. Normally, a program will encapsulate these calls into a method of it's own, so your first disassembly step can be in identifying the methods and naming them appropriately with names like 'File_open', 'File_read', and so on. Likewise, giving the passed parameters an appropriate name. In IDA, the 'Y' command can be used to set up an appropriate method signature for methods. By properly naming the method and it's parameters, this will help you in all the methods that call those methods. | ||
For example, if a read method has a 'size' parameter and a 'buffer' parameter, then if a method that calls it passes '200' for the size, and a reference from a location on the stack, you can be confident that the stack entry can be called something like 'readBuffer', and use the '*' (array size) key when looking at the Stack View (Ctrl-K) to set the size of the array to 200 bytes. | For example, if a read method has a 'size' parameter and a 'buffer' parameter, then if a method that calls it passes '200' for the size, and a reference from a location on the stack, you can be confident that the stack entry can be called something like 'readBuffer', and use the '*' (array size) key when looking at the Stack View (Ctrl-K) to set the size of the array to 200 bytes. | ||