Chapter 19: Closing the Holes: Mitigation
487
PART IV
Figure 19-1
Structure of an
ELF executable
file
Many other sections are commonly found in ELF executables. Refer to the ELF specification
for more detailed information.
Microsoft Windows PE files also have a well-defined structure as defined by
Microsoft??™s Portable Executable and Common Object File Format Specification. While
the physical structure of a PE file differs significantly from an ELF file, from a logical perspective,
many similar elements exist in both. Like ELF files, PE files must detail the layout
of the file, including the location of code and data, virtual address information, and
dynamic linking requirements. By gaining an understanding of either one of these file
formats, you will be well prepared to understand the format of additional types of executable
files.
Patch Development and Application
Patching an executable file is a nontrivial process. While the changes you wish to make
to a binary may be very clear to you, the capability to make those changes may simply
not exist. Any changes made to a compiled binary must ensure not only that the operation
of the vulnerable program is corrected, but also that the structure of the binary file
image is not corrupted.
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