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readpe.py
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#! /usr/bin/env python
import sys, os
if sys.version_info[0] == 2 and sys.version_info[1] < 4:
sys.stderr.write("python version older than 2.4 is not supported\n")
sys.exit(1)
sys.path.insert(1, os.path.abspath(sys.path[0]+'/..'))
from elfesteem import pe_init, pe
import struct
def test_rebuild(e):
bin = str(e)
if bin != raw:
print("ERROR: PE file is not reconstructed identical")
f = pe_init.PE(bin)
bin2 = str(f)
if bin != bin2:
print("ERROR: PE does not even have a fixpoint")
def print_petype(e):
if hasattr(e, 'COFFhdr'): COFFhdr = e.COFFhdr
else: COFFhdr = e.Coffhdr
machine = pe.constants['IMAGE_FILE_MACHINE'].get(COFFhdr.machine,
"UNKNOWN(%#x)" % COFFhdr.machine)
if hasattr(e, 'NThdr'):
print("PE for %s (%s header)"%(machine,struct.pack("<H",e.DOShdr.magic)))
else:
print("COFF %s endian for %s"%({'<':'little','>':'big'}[e.sex],machine))
print("COFF: %d sections, %d symbols; flags %#x; szopthdr %#x" % (
COFFhdr.numberofsections,
COFFhdr.numberofsymbols,
COFFhdr.characteristics,
COFFhdr.sizeofoptionalheader,
))
for flag in pe.constants['IMAGE_FILE_FLAG']:
if COFFhdr.characteristics & flag:
print(" %s"%pe.constants['IMAGE_FILE_FLAG'][flag])
if COFFhdr.sizeofoptionalheader:
if hasattr(e.Opthdr, 'majorlinkerversion'):
vstamp = '%d.%d' % ( e.Opthdr.majorlinkerversion,
e.Opthdr.minorlinkerversion )
else:
# Sometimes, the doc does not say how vstamp is splitted in
# major / minor
vstamp = '%#x' % e.Opthdr.vstamp
magic = pe.constants['IMAGE_OPTIONAL_HDR_MAGIC'].get(e.Opthdr.magic,
"UNKNOWN(%#x)" % e.Opthdr.magic)
print("OPThdr magic: %s; version %s; Entry: %#10x" % (
magic, vstamp, e.Opthdr.entry))
if COFFhdr.pointertosymboltable:
strtab_off = COFFhdr.pointertosymboltable + 18 * COFFhdr.numberofsymbols
print("SymbolTable: %#x; %d symbols; strtab of len %d bytes" % (
COFFhdr.pointertosymboltable,
COFFhdr.numberofsymbols,
len(e.content) - strtab_off,
))
print("MaxAddr %#x" % e.virt.max_addr())
if hasattr(e, 'NThdr'):
print("NThdr: Sig %s OSver %d.%d IMGver %d.%d subsystem %s v%d.%d" % (
struct.pack("<H",e.NTsig.signature),
e.NThdr.majoroperatingsystemversion,
e.NThdr.minoroperatingsystemversion,
e.NThdr.MajorImageVersion,
e.NThdr.MinorImageVersion,
pe.constants['IMAGE_SUBSYSTEM'].get(e.NThdr.subsystem,
'unk%d'%e.NThdr.subsystem),
e.NThdr.majorsubsystemversion,
e.NThdr.minorsubsystemversion,
))
print(" ImageBase %#x s_align %#x f_align %#x sz_img %#x sz_hdr %#x" % (
e.NThdr.ImageBase,
e.NThdr.sectionalignment,
e.NThdr.filealignment,
e.NThdr.sizeofimage,
e.NThdr.sizeofheaders,
))
print(" CheckSum %#x sz_sr %#x sz_sc %#x sz_hr %#x sz_hc %#x" % (
e.NThdr.CheckSum,
e.NThdr.sizeofstackreserve,
e.NThdr.sizeofstackcommit,
e.NThdr.sizeofheapreserve,
e.NThdr.sizeofheapcommit,
))
print(" NbDir %d DLLchar %#x LoaderFlg %#x Reserved %#x" % (
e.NThdr.numberofrvaandsizes,
e.NThdr.dllcharacteristics,
e.NThdr.loaderflags,
e.NThdr.Reserved1,
))
def print_sections(e):
print("\nSECTIONS")
print("No Name offset rsize vsize/paddr vaddr flags")
for i, s in enumerate(e.SHList):
print("%2d %s" % (i, s))
if hasattr(e, 'NThdr'):
print("\nNT HEADERS")
print("No Name addr memsz")
for i, s in enumerate(e.NThdr.optentries):
if i == pe.DIRECTORY_ENTRY_SECURITY:
n = e.getsectionbyoff(s.rva)
else:
n = e.getsectionbyrva(s.rva)
if n is None:
class NoSection(object):
name = '<no section>'
n = NoSection()
dirname = pe.constants['DIRECTORY_ENTRY'].get(i, '<noname>')
if s.size == 0: name = ''
else: name = n.name.strip('\0')
print("%2d %15s %#10x %#10x %12s"%(i, dirname, s.rva, s.size, name))
def print_symtab(e):
if hasattr(e, 'Symbols'):
print(e.Symbols.display())
if hasattr(e, 'OSF1Symbols'):
print("\nOSF1/Tru64 SYMBOLS")
print("%r"%e.OSF1Symbols)
from operator import itemgetter
def print_layout(e, filesz):
if filesz == 0:
print("\nEMPTY FILE")
return
layout = []
of = 0
if hasattr(e, 'COFFhdr'): COFFhdr = e.COFFhdr
else: COFFhdr = e.Coffhdr
if hasattr(e, 'NThdr'): # PE
if hasattr(e, 'DOShdr'): DOShdr = e.DOShdr
else: DOShdr = e.Doshdr
layout.append((0, e.NThdr.sizeofheaders, 'Headers'))
layout.append((0, len(DOShdr.pack()), 'DOS header'))
of += DOShdr.lfanew
layout.append((of, len(e.NTsig.pack()), 'NT sig'))
of += len(e.NTsig.pack())
layout.append((of, len(COFFhdr.pack()), 'COFF header'))
of += len(COFFhdr.pack())
if COFFhdr.sizeofoptionalheader > 0:
layout.append((of, len(e.Opthdr.pack()), 'Optional headers'))
if hasattr(e, 'NThdr'): # PE
layout.append((of + len(e.Opthdr.pack()), len(e.NThdr.pack()), 'NT header'))
layout.append((of, COFFhdr.sizeofoptionalheader, 'NT + Optional headers'))
of += COFFhdr.sizeofoptionalheader
layout.append((of, len(e.SHList.pack()), 'List of Sections'))
of += len(e.SHList.pack())
if hasattr(e, 'NThdr'):
layout.append((DOShdr.lfanew, of-DOShdr.lfanew, 'PE header'))
for i, s in enumerate(e.SHList):
if not s.is_in_file():
continue
if i == 0 and s.name.startswith('$'):
# '$build.attributes' dummy section is seen in TI COFF sample file
# PECOFF reference documentation 4.2 explains the special
# interpretation of $ in section names, which is compatible
# with ignoring sections starting with $
continue
# We use rawsize instead of rsize, because we want the size in bytes
layout.append((s.scnptr, s.rawsize,
'Section '+s.name.strip('\0')))
if s.nreloc:
layout.append((s.relptr, s.nreloc*10,
'Relocs '+s.name.strip('\0')))
if s.nlnno:
nlnno = s.nlnno
if s.lnnoptr+s.nlnno*6 > filesz:
nlnno = (filesz-s.lnnoptr)//6
print("LINENO for section %s is %d and should probably be %s" % (s.name.strip('\0'), s.nlnno, nlnno))
layout.append((s.lnnoptr, nlnno*6,
'LineNo '+s.name.strip('\0')))
if hasattr(e, 'OSF1Symbols'):
layout.append((COFFhdr.pointertosymboltable,
e.OSF1Symbols.bytelen,
'COFF/OSF1 Symbols Header'))
stab_end = COFFhdr.pointertosymboltable + e.OSF1Symbols.bytelen
for start, count, size, name in (
('cbLineOffset', 'cbLine', 1, 'Packed Line Number Entries'),
('cbDnOffset', 'idnMax', 0, 'Obsolete'),
('cbPdOffset', 'ipdMax', 64, 'Procedure Descriptors'),
('cbSymOffset', 'isymMax', 16, 'Local Symbols'),
('cbOptOffset', 'ioptMax', 1, 'Optimization Entries'),
('cbAuxOffset', 'iauxMax', 4, 'Auxiliary Symbols'),
('cbSsOffset', 'issMax', 1, 'Local Strings'),
('cbSsExtOffset', 'issExtMax', 1, 'External Strings'),
('cbFdOffset', 'ifdMax', 96, 'File Descriptors'),
('cbRfdOffset', 'crfd', 4, 'Relative File Descriptors'),
('cbExtOffset', 'iextMax', 24, 'External Symbols'),
):
if getattr(e.OSF1Symbols, start) != 0:
layout.append((getattr(e.OSF1Symbols, start),
getattr(e.OSF1Symbols, count) * size,
'COFF/OSF1 %s'%name))
stab_end_s = getattr(e.OSF1Symbols, start) + \
getattr(e.OSF1Symbols, count) * size
if stab_end < stab_end_s: stab_end = stab_end_s
layout.append((COFFhdr.pointertosymboltable,
stab_end - COFFhdr.pointertosymboltable,
'COFF/OSF1 Symbols'))
if hasattr(e, 'Symbols'):
layout.append((COFFhdr.pointertosymboltable,
e.Symbols.bytelen,
'COFF Symbols'))
if hasattr(e, 'SymbolStrings'):
layout.append((COFFhdr.pointertosymboltable +
e.Symbols.bytelen,
len(e.SymbolStrings.pack()),
'COFF SymbolStrings'))
if hasattr(e, 'NThdr'):
for i, s in enumerate(e.NThdr.optentries):
if s.rva != 0:
if i == pe.DIRECTORY_ENTRY_SECURITY:
# SECURITY vaddr is an offset, not a RVA!
of = s.rva
if of >= filesz: of = None
else:
of = e.rva2off(s.rva)
if of is None:
# e.g. Ange Albertini's foldedhdr.exe
continue
layout.append((of, s.size,
'DirEnt '+pe.constants['DIRECTORY_ENTRY'][i]))
if i in (pe.DIRECTORY_ENTRY_IMPORT,
pe.DIRECTORY_ENTRY_DELAY_IMPORT):
directory, name = {
pe.DIRECTORY_ENTRY_IMPORT: ('DirImport','IMPORT'),
pe.DIRECTORY_ENTRY_DELAY_IMPORT: ('DirDelay', 'DELAY '),
}[i]
directory = getattr(e, directory)
layout.append((
directory._off,
directory._size,
'%s Descriptors'%name))
for idx, d in enumerate(directory):
# for a .exe created by mingw,
# there is a RVA before each thunk
if hasattr(d, 'ILT'):
layout.append((
e.rva2off(d.originalfirstthunk),
d.ILT.bytelen,
'%s Thunks:original [%d]' % (name, idx)))
if hasattr(d, 'IAT'):
layout.append((
e.rva2off(d.firstthunk),
d.IAT.bytelen,
'%s Thunks:current [%d]' % (name, idx)))
if hasattr(d, 'name'):
# Sometimes aligned to 2 bytes
size = d.name.bytelen
if idx+1 == len(directory) or \
d.name_rva+size<directory[idx+1].name_rva:
if size % 2: size += 1
layout.append((
e.rva2off(d.name_rva),
size,
'%s DLLname [%d]' % (name, idx)))
for jdx, t in enumerate(getattr(d, 'ILT', [])):
if not hasattr(t.obj, '_size'):
continue
# Aligned to 2 bytes
size = t.obj.bytelen
if size % 2: size += 1
layout.append((
e.rva2off(t.rva),
size,
'%s IMPname [%d,%d]' % (name, idx, jdx)))
for jdx, t in enumerate(getattr(d, 'IAT', [])):
if not hasattr(t.obj, '_size'):
continue
if jdx < len(getattr(d, 'ILT', [])) \
and hasattr(d.ILT[jdx].obj, '_size'):
# assert t.rva == d.ILT[jdx].rva
# Not true for some files,
# e.g. Ange Albertini's imports_bogusIAT.exe
continue
# Aligned to 2 bytes
size = t.obj.bytelen
if size % 2: size += 1
layout.append((
e.rva2off(t.rva),
size,
'%s IATname [%d,%d]' % (name, idx, jdx)))
elif i == pe.DIRECTORY_ENTRY_EXPORT:
directory = e.DirExport
layout.append((
directory._off,
directory._size,
'EXPORT Descriptor'))
assert 1 == len(directory)
d = directory[0]
layout.append((
e.rva2off(d.name_rva),
d.name.bytelen,
'EXPORT DLLname'))
if d.addressoffunctions:
layout.append((
e.rva2off(d.addressoffunctions),
d.EAT.bytelen,
'EXPORT Address Table'))
if d.addressofordinals:
layout.append((
e.rva2off(d.addressofordinals),
d.EOT.bytelen,
'EXPORT Ordinal Table'))
if d.addressofnames:
layout.append((
e.rva2off(d.addressofnames),
d.ENPT.bytelen,
'EXPORT Name Pointers Table'))
for jdx, t in enumerate(d.EAT):
if not hasattr(t, 'name'): continue
layout.append((
e.rva2off(t.rva),
t.name.bytelen,
'EXPORT Forwarder [%d]' % jdx))
for jdx, t in enumerate(d.ENPT):
layout.append((
e.rva2off(t.rva),
t.name.bytelen,
'EXPORT FUNCname [%d]' % jdx))
elif i == pe.DIRECTORY_ENTRY_RESOURCE:
directory = e.DirRes
layout.append((
directory._off,
directory._size,
'RESOURCE Descriptor'))
def resdir_layout(t, branch):
for idx, x in enumerate(t.entries):
b = branch+[idx]
if hasattr(x, 'dir'):
layout.append((
x.base + (x.offset & 0x7FFFFFFF),
x.dir.bytelen,
'RESOURCE Node %s'%b))
resdir_layout(x.dir,b)
if hasattr(x, 'data'):
layout.append((
x.base + (x.offset & 0x7FFFFFFF),
x.data.bytelen,
'RESOURCE DataDesc %s'%b))
layout.append((
x.rva2off(x.data.rva),
x.data.size,
'RESOURCE Data %s'%b))
if hasattr(x, 'name'):
layout.append((
x.base + (x.id & 0x7FFFFFFF),
x.name.bytelen,
'RESOURCE Name %s'%b))
for t in directory:
resdir_layout(t, [])
elif i == pe.DIRECTORY_ENTRY_BASERELOC:
directory = e.DirReloc
of = directory._off
for idx, t in enumerate(directory):
layout.append((
of,
t.bytelen,
'BASERELOC Block %d'%idx))
of += t.bytelen
print("\nFILE CONTENT LAYOUT")
not_in_section = [l for l in layout if l[0] is None]
layout = [l for l in layout if l[0] is not None]
def section_extract(x):
s = x[2].split()[0]
o = ['Section', 'DirEnt']
if s in o: return (o.index(s), x)
else: return (len(o), x)
layout.sort(key=section_extract)
layout.sort(key=itemgetter(1), reverse=True)
layout.sort(key=itemgetter(0))
format = "%#10x-%#010x %s%s"
def unknown(b, f, dots):
if e.content[b:f] == pe.data_null*(f-b):
msg = 'zeroes'
else:
msg = '(unknown, %d bytes)' % (f-b)
print(format % (b, f, ". " * dots, msg))
context = [(0, filesz)]
for l in [l for l in layout if l[0] != None]:
if context[-1][0] <= l[0] and l[0]+l[1] <= context[-1][1]:
if context[-1][0] < l[0]:
b, f = context[-1][0], l[0]
unknown(b, f, len(context)-1)
else:
while l[0] >= context[-1][1]:
b, f = context[-1][1], min(l[0], context[-2][1])
if f > b:
unknown(b, f, len(context)-2)
context.pop()
context.append((l[0],l[0]+l[1]))
print(format % (l[0], l[0]+l[1], ". " * (len(context)-2),
' '.join(l[2:])))
# If we did not reach the end of the file
l = (filesz,)
while len(context) > 1 and l[0] >= context[-1][1]:
b, f = context[-1][1], min(l[0], context[-2][1])
if f > b:
unknown(b, f, len(context)-2)
context.pop()
if context[-1][1] > filesz:
print(format % (context[-1][1], filesz, "", "(went after EOF!)"))
for l in not_in_section:
print("Not in a section: %s" % (' '.join(l[2:])))
def pe_dir_display(e):
if hasattr(e, 'DirImport'): print(e.DirImport.display())
if hasattr(e, 'DirExport'): print(e.DirExport.display())
if hasattr(e, 'DirDelay'): print(e.DirDelay.display())
if hasattr(e, 'DirRes'): print(e.DirRes.display())
if hasattr(e, 'DirReloc'): print(e.DirReloc.display())
if __name__ == '__main__':
arg_keys = {
'H': ('headers', 'Headers'),
'S': ('sections', 'Sections'),
'D': ('directories', 'Directories'),
'r': ('reltab', 'Relocation sections'),
's': ('symtab', 'Symbol table'),
'l': ('layout', 'File content layout'),
#'d': ('dynsym', 'Dynamic symbols'),
}
try:
import argparse
parser = argparse.ArgumentParser()
for key in arg_keys:
const, help = arg_keys[key]
parser.add_argument('-'+key,
dest='options',
action='append_const',
const=const,
help=help)
parser.add_argument('file', nargs='+', help='ELF file(s)')
args = parser.parse_args()
if args.options is None:
args.options = []
except ImportError:
# Emulate argparse for python < 2.7
# We miss e.g. the help
class Args(object):
file = []
options = []
args = Args()
for arg in sys.argv[1:]:
if arg.startswith('-'):
for key in arg_keys:
if key in arg: args.options.append(arg_keys[key][0])
else:
args.file.append(arg)
for file in args.file:
if len(args.file) > 1:
print("\nFile: %s" % file)
fd = open(file, 'rb')
try:
raw = fd.read()
finally:
fd.close()
if raw[:2] == struct.pack("2B", 0x48,0x52):
# IDA's bochsys.dll is a normal PE with its magic number replaced
# by 'HR', probably meaning HexRays.
raw = struct.pack("2B", 0x4d,0x5a) + raw[2:]
try:
e = pe_init.PE(raw)
except ValueError:
try:
e = pe_init.Coff(raw)
except ValueError:
print('Not a valid COFF')
continue
#test_rebuild(e)
if 'headers' in args.options:
print_petype(e)
if 'sections' in args.options:
print_sections(e)
if 'symtab' in args.options:
print_symtab(e)
if 'reltab' in args.options:
for s in e.SHList:
if s.nreloc:
print('Relocs '+s.name.strip('\0'))
for r in s.data.relocs:
print(' %r'%r)
if 'layout' in args.options:
print_layout(e,len(raw))
if 'directories' in args.options:
pe_dir_display(e)
# http://media.blackhat.com/bh-us-11/Vuksan/BH_US_11_VuksanPericin_PECOFF_Slides.pdf