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elf.py
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elf.py
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import bin as binr
import io
class bcolors:
HEADER = '\033[97m'
OKBLUE = '\033[94m'
OKGREEN = '\033[92m'
WARNING = '\033[93m'
FAIL = '\033[91m'
ENDC = '\033[0m'
bs = binr.bin2str
lstr = lambda string: bcolors.HEADER + "|" + "{:<86}".format(string) + bcolors.HEADER + "|"
# reads bytes until null terminator, returns the string
def iterateUntilNull(offset,binary):
name = []
o = offset
finished = False
while finished == False:
b = binary[o]
if hex(ord(b)) != "0x0":
name.append(b)
o = o+1
elif hex(ord(b)) == "0x0":
finished = True
return "".join(name)
#Get the name of this section header
def getSectionHeaderName(sections,sh):
for section in sections:
name_off = int(section['sh_name'],16)
name = iterateUntilNull(name_off,sh)
section['name'] = name
return sections
# Get all the section headers from the table
def parseSectionHeaderTable(path, offset, arch, endian, entNum, entSize, nameIndex, sh):
f = io.open(path,'rb')
if sh:
print bcolors.FAIL + "\nSECTION HEADER TABLE\n" + bcolors.HEADER
print "Should be %s%s%s entries of %s%s%s bytes." % (bcolors.WARNING,int(entNum,16), bcolors.HEADER, bcolors.WARNING, int(entSize,16), bcolors.HEADER)
print "Table: Looking up section header table at %s0x%s%s" % (bcolors.OKBLUE,offset ,bcolors.HEADER)
# nameIndex is the index of the .shstrtab
nI = int(nameIndex,16)
sections = []
for y in range(0,int(entNum,16)):
# sf = index * entry size
sf = int(y)*int(str(entSize),16)
# Offset of the start of section header table
tf = int(str(offset),16)
# section offset = table offset + (number of entries * size of entries)
soffset = tf + sf
section = parseSectionHeaders(f, soffset, arch, endian, entNum, entSize, nameIndex, sh)
sections.append(section)
if y == nI:
# this is the .shstrtab section, need to get the contents of this section
f.close()
f = io.open(path,'rb')
f.seek(int(section['sh_offset'],16))
shstrtab = f.read(int(section['sh_size'],16))
# Function that iterates through all sections[], gets name from shstrtab
named = getSectionHeaderName(sections, shstrtab)
return named
def parseSectionHeaders(elfFile, offset, arch, endian, entNum, entSize, nameIndex, sh):
def parseFlags(flg):
flags = int(flg)
flagStr = ""
pfl = lambda flags, mask, code, string: string+code if flags & mask else string+" "
# First bit for write
flagStr = pfl(flags, 0b1, "W", flagStr)
flagStr = pfl(flags, 0b10, "A", flagStr)
flagStr = pfl(flags, 0b100, "X", flagStr)
flagStr = pfl(flags, 0x10, "M", flagStr)
flagStr = pfl(flags, 0x20, "S", flagStr)
flagStr = pfl(flags, 0x40, "I", flagStr)
flagStr = pfl(flags, 0x80, "L", flagStr)
return flagStr
def getSHType(byte):
sh_types = {
0: "SHT_NULL",
1: "SHT_PROGBITS",
2: "SHT_SYMTAB",
3: "SHT_STRTAB",
4: "SHT_RELA",
5: "SHT_HASH",
6: "SHT_DYNAMIC",
7: "SHT_NOTE",
8: "SHT_NOBITS",
9: "SHT_REL",
10: "SHT_LIB",
11: "SHT_DYNSYM",
14: "SHT_INT_ARRAY",
15: "SHT_FINI_ARRAY",
16: "SHT_PREINIT_ARRAY",
17: "SHT_GROUP",
18: "SHY_SYMTAB_SHNDX",
19: "SHT_NUM",
1610612736: "SHT_LOOS"
}
return sh_types.get(byte,"Unknown")
elfFile.seek(0)
elfFile.seek(offset)
s = elfFile.read(int(entSize,16))
bsr = lambda x, y : bs(s[x:y], endian)
sh_name = bsr(0,4)
t = bsr(4,8)
sh_type = getSHType(int(t,16))
if arch=="64-bit":
sh_flags = bsr(8,16)
sh_addr = bsr(16,24)
sh_offset = bsr(24,32)
sh_size = bsr(32,40)
sh_link = bsr(40,44)
sh_info = bsr(44,48)
sh_addralign = bsr(48,56)
sh_entsize = bsr(56,64)
elif arch=="32-bit":
sh_flags = bsr(8,12)
sh_addr = bsr(12,16)
sh_offset = bsr(16,20)
sh_size = bsr(20,24)
sh_link = bsr(24,28)
sh_info = bsr(28,32)
sh_addralign = bsr(32,36)
sh_entsize = bsr(36,40)
parsed_flags = parseFlags(sh_flags)
if not sh_name:
sh_name = "error"
obj = {
'parsed_flags' : parsed_flags,
'sh_name' : sh_name,
'sh_type' : t,
'type' : sh_type,
'sh_flags' : sh_flags,
'sh_addr' : sh_addr,
'sh_offset' : sh_offset,
'sh_size' : sh_size,
'sh_link' : sh_link,
'sh_info' : sh_info,
'sh_addralign' : sh_addralign,
'sh_entsize' : sh_entsize,
'soffset' : offset
}
return obj
def parseELFHeader(elfFile, fh):
f = io.open(elfFile,'rb')
bsr = lambda x, y : bs(h[x:y], endian)
h = f.read(64)
magic = h[0:4]
if hex(ord(h[4]))=="0x1":
arch = "32-bit"
elif hex(ord(h[4]))=="0x2":
arch = "64-bit"
else:
arch = "unknown"
if hex(ord(h[5]))=="0x1":
endian = "Little"
elif hex(ord(h[5]))=="0x2":
endian = "Big"
else:
endian = "unknown"
# h[6] is always 1 for ELF original version
def getABI(byte):
byte = ord(byte)
abi = {
0 : "System V (Default Unix Application Binary Interface)",
1 : "HP-UX",
2 : "NetBSD",
3 : "Linux",
4 : "GNU Hurd",
6 : "Solaris",
7 : "AIX",
8 : "IRIX",
9 : "FreeBSD",
10: "Tru64",
11: "Novell Modesto",
12: "OpenBSD",
13: "OpenVMS",
14: "NonStop Kernel",
15: "AROS",
16: "Fenix OS",
17: "CloudABI"
}
return abi.get(byte, "Unknown")
abi = getABI(h[7])
abi_vers = ord(h[8])
if abi_vers == 0 :
abi_vers = "Unknown"
# h[9-15] are e_ident[EI_PAD], unused padding
def getFileType(byte):
Byte = int(hex(ord(byte)),16)
types = {
int(0x00) : "ET_NONE",
int(0x01) : "ET_REL",
int(0x02) : "ET_EXEC",
int(0x03) : "ET_DYN",
int(0x04) : "ET_CORE",
}
return types.get(Byte, "UNKNOWN")
fileType = getFileType(h[16])
def getArch(byte):
archs = {
"0x0" : "Unspecified",
"0x2" : "SPARC",
"0x3" : "x86",
"0x8" : "MIPS",
"0x14" : "PowerPC",
"0x16" : "S390",
"0x28" : "ARM",
"0x2a" : "SuperH",
"0x32" : "IA-64",
"0x3e" : "x86_64",
"0Xb7" : "AArch64",
"0xf3" : "RISC-V"
}
err = "Unknown: " + hex(ord(byte))
return archs.get(hex(ord(byte)), err)
iarch = getArch(h[18])
# e_version (h[20]) = 1 for elf, takes up 4 bytes
if arch=="64-bit":
entry = bsr(24,32)
pht = bsr(32,40) # program header table
sht = bsr(40,48) # section header table
e_flags = bsr(48,52)
e_ehsize = bsr(52,54)
e_phentsize = bsr(54,56)
e_phnum = bsr(56,58)
e_shentsize = bsr(58,60)
e_shnum = bsr(60,62)
e_shstrndx = bsr(62,64)
elif arch=="32-bit":
entry = bsr(24,28)
pht = bsr(28,32)
sht = bsr(32,36)
e_flags = bsr(36,40)
e_ehsize = bsr(40,42)
e_phentsize = bsr(42,44)
e_phnum = bsr(44,46)
e_shentsize = bsr(46,48)
e_shnum = bsr(48,50)
e_shstrndx = bsr(50,52)
if fh:
print bcolors.HEADER + "+--------------------------------------------------------------------------------------+"
print "\n\t"+bcolors.FAIL+"EXECUTABLE FILE HEADERS\n"+bcolors.HEADER
print "\tFormat: \033[93mELF (Executable and Linkable Format)\033[97m"
print "\tArchitecture: \033[93m%s\033[97m " % arch
print "\tEndian: \033[93m%s\033[97m " % endian
print "\tABI: \033[93m%s\033[97m, Version: \033[93m%s\033[97m " % (abi, abi_vers)
print "\tFile Type: \033[93m%s\033[97m " % fileType
print "\tInstruction set architecture: \033[93m%s\033[97m " % iarch
print "\tEntry Point: \033[96m0x%s\033[97m" % entry
print "\tStart of Program Header Table: \033[96m0x%s\033[97m" % pht
print "\tStart of Section Header Table: \033[96m0x%s\033[97m" % sht
print "\te_flags: \033[96m0x%s\033[97m" % e_flags
print "\tHeader size: \033[96m0x%s\033[97m (\033[94m%s bytes\033[97m)" % (e_ehsize, int(e_ehsize, 16))
print "\tProgram Header Table entry size: \033[96m0x%s\033[97m (\033[94m%s bytes\033[97m)" % (e_phentsize, int(e_phentsize, 16))
print "\tNumber of entries in Program Header Table: \033[96m0x%s\033[97m (\033[94m%s entries\033[97m)" % (e_phnum, int(e_phnum, 16))
print "\tSection Header Table entry size: \033[96m0x%s\033[97m (\033[94m%s bytes\033[97m)" % (e_shentsize, int(e_shentsize,16))
print "\tNumber of entries in Section Header Table: \033[96m0x%s\033[97m (\033[94m%s entries\033[97m)" % (e_shnum, int(e_shnum, 16))
print "\tIndex of Section Table Header entry containing section names: \033[96m0x%s\033[97m " % e_shstrndx
print bcolors.HEADER + "\n+--------------------------------------------------------------------------------------+" + bcolors.ENDC
obj = {
'format': 'ELF',
'magic': magic,
'arch': arch,
'endian': endian,
'abi': abi,
'fileType': fileType,
'iarch': iarch,
'entry': entry,
'pht': pht,
'sht': sht,
'e_flags': e_flags,
'e_ehsize': e_ehsize,
'e_phentsize': e_phentsize,
'e_phnum': e_phnum,
'e_shentsize': e_shentsize,
'e_shnum': e_shnum,
'e_shstrndx': e_shstrndx
}
return obj