pe-parse/python

pepy

pepy (pronounced p-pie) is a python binding to the pe-parse parser.

Building

If you can build pe-parse and have a working python environment (headers and libraries) you can build pepy.

Python 2.7

1. Build pepy:

• python setup.py build

2. Install pepy:

• python setup.py install

Building on Windows: If you get a build error of 'Unable to find vcvarsall.bat', you must set the VS90COMNTOOLS environment variable prior to the appropriate path as per this SO article:

While running setup.py for package installations, Python 2.7 searches for an installed Visual Studio 2008. You can trick Python to use a newer Visual Studio by setting the correct path in VS90COMNTOOLS environment variable before calling setup.py.

Execute the following command based on the version of Visual Studio installed:

• Visual Studio 2010 (VS10): SET VS90COMNTOOLS=%VS100COMNTOOLS%
• Visual Studio 2012 (VS11): SET VS90COMNTOOLS=%VS110COMNTOOLS%
• Visual Studio 2013 (VS12): SET VS90COMNTOOLS=%VS120COMNTOOLS%
• Visual Studio 2015/2017 (VS14): SET VS90COMNTOOLS=%VS140COMNTOOLS%

Python 3.x

1. Build pepy:

• python3 setup.py build

2. Install pepy:

• python3 setup.py install

Building on Windows: Python 3.x is typically installed as python.exe NOT python3.exe.

Using

Parsed object

There are a number of objects involved in pepy. The main one is the parsed object. This object is returned by the parse method.

import pepy
p = pepy.parse("/path/to/exe")

The parsed object has a number of methods:

• get_entry_point: Return the entry point address
• get_machine_as_str: Return the machine as a human readable string
• get_subsystem_as_str: Return the subsystem as a human readable string
• get_bytes: Return the first N bytes at a given address
• get_sections: Return a list of section objects
• get_imports: Return a list of import objects
• get_exports: Return a list of export objects
• get_relocations: Return a list of relocation objects
• get_resources: Return a list of resource objects

The parsed object has a number of attributes:

• signature
• machine
• numberofsections
• timedatestamp
• numberofsymbols
• characteristics
• magic
• majorlinkerver
• minorlinkerver
• codesize
• initdatasize
• uninitdatasize
• entrypointaddr
• baseofcode
• baseofdata
• imagebase
• sectionalignement
• filealignment
• majorosver
• minorosver
• win32ver
• imagesize
• headersize
• checksum
• subsystem
• dllcharacteristics
• stackreservesize
• stackcommitsize
• heapreservesize
• heapcommitsize
• loaderflags
• rvasandsize

Example:

import time
import pepy

p = pepy.parse("/path/to/exe")
print "Timedatestamp: %s" % time.strftime("%Y-%m-%d %H:%M:%S", time.localtime(p.timedatestamp))
ep = p.get_entry_point()
print "Entry point: 0x%x" % ep

The get_sections, get_imports, get_exports, get_relocations and get_resources methods each return a list of objects. The type of object depends upon the method called. get_sections returns a list of section objects, get_imports returns a list of import objects, etc.

Section Object

The section object has the following attributes:

• base
• length
• virtaddr
• virtsize
• numrelocs
• numlinenums
• characteristics
• data

Import Object

The import object has the following attributes:

• sym
• name
• addr

Export Object

The export object has the following attributes:

• mod
• func
• addr

Relocation Object

The relocation object has the following attributes:

• type
• addr

Resource Object

The resource object has the following attributes:

• type_str
• name_str
• lang_str
• type
• name
• lang
• codepage
• RVA
• size
• data

The resource object has the following methods:

• type_as_str

Resources are stored in a directory structure. The first three levels of the are called type, name and lang. Each of these levels can have either a pre-defined value or a custom string. The pre-defined values are stored in the type, name and lang attributes. If a custom string is found it will be stored in the type_str, name_str and lang_str attributes. The type_as_str method can be used to convert a pre-defined type value to a string representation.

The following code shows how to iterate through resources:

import pepy

from hashlib import md5

p = pepy.parse(sys.argv[1])
resources = p.get_resources()
print "Resources: (%i)" % len(resources)
for resource in resources:
    print "[+] MD5: (%i) %s" % (len(resource.data), md5(resource.data).hexdigest())
    if resource.type_str:
        print "\tType string: %s" % resource.type_str
    else:
        print "\tType: %s (%s)" % (hex(resource.type), resource.type_as_str())
    if resource.name_str:
        print "\tName string: %s" % resource.name_str
    else:
        print "\tName: %s" % hex(resource.name)
    if resource.lang_str:
        print "\tLang string: %s" % resource.lang_str
    else:
        print "\tLang: %s" % hex(resource.lang)
    print "\tCodepage: %s" % hex(resource.codepage)
    print "\tRVA: %s" % hex(resource.RVA)
    print "\tSize: %s" % hex(resource.size)

Note that some binaries (particularly packed) may have corrupt resource entries. In these cases you may find that len(resource.data) is 0 but resource.size is greater than 0. The size attribute is the size of the data as declared by the resource data entry.

Authors

pe-parse was designed and implemented by Andrew Ruef (andrew@trailofbits.com) pepy was written by Wesley Shields (wxs@atarininja.org)