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Learning Linux Binary Analysis

You're reading from   Learning Linux Binary Analysis Learning Linux Binary Analysis

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Product type Paperback
Published in Feb 2016
Publisher Packt
ISBN-13 9781782167105
Length 282 pages
Edition 1st Edition
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Author (1):
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Ryan "elfmaster" O'Neill Ryan "elfmaster" O'Neill
Author Profile Icon Ryan "elfmaster" O'Neill
Ryan "elfmaster" O'Neill
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Table of Contents (11) Chapters Close

Preface 1. The Linux Environment and Its Tools FREE CHAPTER 2. The ELF Binary Format 3. Linux Process Tracing 4. ELF Virus Technology – Linux/Unix Viruses 5. Linux Binary Protection 6. ELF Binary Forensics in Linux 7. Process Memory Forensics 8. ECFS – Extended Core File Snapshot Technology 9. Linux /proc/kcore Analysis Index

ELF symbols

Symbols are a symbolic reference to some type of data or code such as a global variable or function. For instance, the printf() function is going to have a symbol entry that points to it in the dynamic symbol table .dynsym. In most shared libraries and dynamically linked executables, there exist two symbol tables. In the readelf -S output shown previously, you can see two sections: .dynsym and .symtab.

The .dynsym contains global symbols that reference symbols from an external source, such as libc functions like printf, whereas the symbols contained in .symtab will contain all of the symbols in .dynsym, as well as the local symbols for the executable, such as global variables, or local functions that you have defined in your code. So .symtab contains all of the symbols, whereas .dynsym contains just the dynamic/global symbols.

So the question is: Why have two symbol tables if .symtab already contains everything that's in .dynsym? If you check out the readelf -S output of...

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