PE (Portable Executable) Analysis

PE Headers

There are many tools to analyze PE headers, such as wxHexEditor, pe-tree.
pe-tree is a tool that views PE files in a tree-view. It will take about a few minutes to open.

pe-tree ./executable
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• IMAGE_DOS_HEADER

  It consists of the first 64 bytes of the PE file. The first two bytes (”4D 5A”) means the “MZ” characters which are an identity of the Portable Executable format.

• DOS_STUB

  It is a small piece of code that only runs if the PE file is incompatible with the system it is being run on. At such time the message “!This program cannot be run in DOS mode" will be displayed.

• IMAGE_NT_HEADERS

  It contains most of the vital information related to the PE file. The starting address of the IMAGE_NT_HEADERS is found in e_lfanew from the IMAGE_DOS_HEADER.

  • NT_HEADERS

    • Signature

      The first 4 bytes of the NT_HEADERS consists of the Signature. It says “50 45 00 00" in hex, which means “PE” in ASCII. It indicates the start of the NT_HEADER.

    • FILE_HEADER

      It contains vital information, such as a type of architecture for which the PE file is written.

    • OPTIONAL_HEADER

      It contains the most important information in the PE headers. Especially, the AddressOfEntryPoint field is significant for reverse engineering.

      • Magic

        It tells whether the PE file is a 32-bit or 64-bit. 0x010B indicates 32-bit, and 0x020B indicates 64-bit.

  • IMAGE_SECTION_HEADER

    It contains various sections like .text, .data, .rsrc, etc.

  • IMAGE_IMPORT_DESCRIPTOR

    It contains information about Windows APIs that the PE file loads when executed.

Identify Packers of Packed Executable

pecheck is a command-line tool which analyze PE files.

pecheck ./executable
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When results appears, check the section name in the PE Section.