png图片增加通道检测
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README.md
10
README.md
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@ -1,3 +1,11 @@
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# ctf_analyze_image
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应对CTF中常见图片分析题
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应对CTF中常见图片分析题，暂时只支持PNG图片
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## 处理能力
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文件信息、文件头修复、文件尾修复、文件尺寸修复、填充数据识别、通道信息检测
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## 使用方法
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```
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python3 ctf_analyze_image.py test.png
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```
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@ -6,345 +6,46 @@ import re
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import sys
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import time
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from PIL import Image
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from type.PNG import PNG
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# from type.JPG import JPG
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# from type.GIF import GIF
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class PNG:
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def __init__(self):
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pass
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# 检测文件格式，返回百分比
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@staticmethod
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def test(data: bytearray):
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return 100
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# 获取图片信息
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@staticmethod
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def get_info(data: bytearray):
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text = b'tEXt'
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index = data.find(text)
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if index > 32:
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length = int.from_bytes(data[index-4: index], byteorder='big')
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chunk_data = data[index+4: index+4+length]
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print('[*] 图像信息：')
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print(bytes(chunk_data).split(b'\x00'))
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info = chunk_data
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return info
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def check_tail(data: bytearray):
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changed = False
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tail = None
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iend = b'\x49\x45\x4E\x44\xAE\x42\x60\x82'
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length = len(data)
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index = data.find(iend)
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if index == -1:
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index = data.find(iend[0:4])
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if index != -1:
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index = index + 4
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else:
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index = index + 8
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if index == -1:
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print('[x] 缺少png文件格式结束标识符IEND')
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elif index < 32:
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print('[x] 缺少png文件格式结束标识符IEND位置貌似不太对')
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else:
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tail = data[index:]
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if len(tail) > 0:
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changed = True
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print('[x] 检测到文件尾部有垃圾数据，已尝试修复')
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return changed, data, tail
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# 修复文件头
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@staticmethod
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def repair_sig(data: bytearray):
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changed = False
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head = None
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print('[*] 检测文件头')
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sig = b'\x89\x50\x4E\x47\x0D\x0A\x1A\x0A'
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index = data.find(sig)
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if index > 0:
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print('[x] 检测到文件头前有垃圾数据，已尝试修复')
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head = bytes(data[:index])
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data = data[index:]
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changed = True
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elif data[0:8] != sig:
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print('[x] 检测到文件头异常，已尝试修复')
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data[0:8] = sig
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changed = True
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return changed, data, head
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# 修复尺寸
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@staticmethod
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def repair_size(data: bytearray):
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changed = False
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print('[*] 检测文件尺寸')
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chunk_begin = 8
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data_begin = chunk_begin + 8
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width_begin = data_begin
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height_begin = data_begin + 4
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length = int.from_bytes(data[chunk_begin:chunk_begin+4], byteorder='big')
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ctype = data[chunk_begin+4: chunk_begin+8] # 应该为 b'\x49\x48\x44\x52'，即 b'IHDR'
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chunk_data = data[data_begin: data_begin+length]
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width = int.from_bytes(chunk_data[0:4], byteorder='big')
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height = int.from_bytes(chunk_data[4:8], byteorder='big')
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crc = int.from_bytes(data[data_begin+length:data_begin+length+4], byteorder='big')
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if PNG.test_ihdr_chunk(ctype + chunk_data, crc):
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print(' - 图片尺寸设置正确')
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else:
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b = False
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if not b:
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print('[x] 尝试修复图片宽度...')
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chunk = ctype + chunk_data
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for i in range(1, 2048):
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chunk[4:8] = i.to_bytes(4, byteorder='big')
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if PNG.test_ihdr_chunk(bytes(chunk), crc):
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width = i
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print(f'[*] 图片宽度修复成功，宽度值为{i}')
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data[width_begin: width_begin+4] = width.to_bytes(4, byteorder='big')
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changed = True
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b = True
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break
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if not b:
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print('[x] 尝试修复图片高度...')
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chunk = ctype + chunk_data
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for i in range(1, 2048):
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chunk[8:12] = i.to_bytes(4, byteorder='big')
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if PNG.test_ihdr_chunk(chunk, crc):
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height = i
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print(f'[*] 图片高度修复成功，宽度值为{i}')
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data[height_begin: height_begin+4] = width.to_bytes(4, byteorder='big')
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changed = True
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b = True
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break
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if not b:
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temp = input(f'当前宽度值为{width}，高度值为{height}，是否尝试将高度值设置为更高？可输入高度值或直接回车：')
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if temp.isdigit():
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height = int(temp)
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data[height_begin: height_begin+4] = height.to_bytes(4, byteorder='big')
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print(f'[*] 已将图片高度设置为{height}')
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changed = True
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return changed, data, width, height
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@staticmethod
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def test_ihdr_chunk(chunk_data, crc):
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crc32 = binascii.crc32(chunk_data) & 0xffffffff
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return crc32 == crc
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class JPG:
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def __init__(self):
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pass
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# 检测文件格式，返回百分比
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@staticmethod
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def test(data: bytearray):
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return 100
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# 获取图片信息
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@staticmethod
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def get_info(data: bytearray):
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info = {}
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return info
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def check_tail(data: bytearray):
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changed = False
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tail = None
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return changed, data, tail
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# 修复文件头
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@staticmethod
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def repair_sig(data: bytearray):
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changed = False
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head = None
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print('[*] 检测文件头')
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sig = b'\x89\x50\x4E\x47\x0D\x0A\x1A\x0A'
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index = data.find(sig)
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if index != -1:
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print('[x] 检测到文件头前有垃圾数据，已尝试修复')
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head = data[:index]
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data = data[index:]
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changed = True
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elif data[0:8] != sig:
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print('[x] 检测到文件头异常，已尝试修复')
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data[0:8] = sig
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changed = True
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return changed, data, head
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# 修复尺寸
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@staticmethod
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def repair_size(data: bytearray):
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changed = False
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print('[*] 检测文件尺寸')
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chunk_begin = 8
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width_begin = chunk_begin + 8
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height_begin = chunk_begin + 12
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length = int.from_bytes(data[chunk_begin:chunk_begin+4], byteorder='big')
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chunk_data = data[chunk_begin+4: chunk_begin+4+length]
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ctype = chunk_data[0:4] # 应该为 b'\x49\x48\x44\x52'，即 b'IHDR'
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width = int.from_bytes(chunk_data[4:8], byteorder='big')
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height = int.from_bytes(chunk_data[8:12], byteorder='big')
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crc = chunk_data[-4:]
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if JPG.test_ihdr_chunk(chunk_data[:-4], crc):
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print(' - 图片尺寸设置正确')
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else:
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if width == 0:
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print('[x] 检测到图片宽度设置异常，尝试修复...')
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for i in range(1, 2048):
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chunk_data[4:8] = i.to_bytes(4, byteorder='big')
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if JPG.test_ihdr_chunk(chunk_data[:-4], crc):
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width = i
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print(f'[*] 图片宽度修复成功，宽度值为{i}')
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data[width_begin: width_begin+4] = width.to_bytes(4, byteorder='big')
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changed = True
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break
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if width == 0:
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print('[x] 图片宽度修复失败')
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temp = input(f'当前宽度值为{width}，高度值为{height}，是否尝试将高度值设置为更高？可输入高度值或直接回车：')
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if temp.isdigit():
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height = int(temp)
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data[height_begin: height_begin+4] = height.to_bytes(4, byteorder='big')
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print(f'[*] 已将图片高度设置为{height}')
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changed = True
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return changed, data
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@staticmethod
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def test_ihdr_chunk(chunk_data, crc):
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crc32 = binascii.crc32(chunk_data) & 0xffffffff
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return crc32 == crc
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class GIF:
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def __init__(self):
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pass
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# 检测文件格式，返回百分比
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@staticmethod
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def test(data: bytearray):
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return 100
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# 获取图片信息
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@staticmethod
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def get_info(data: bytearray):
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info = {}
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return info
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def check_tail(data: bytearray):
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changed = False
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tail = None
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return changed, data, tail
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# 修复文件头
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@staticmethod
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def repair_sig(data: bytearray):
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changed = False
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head = None
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print('[*] 检测文件头')
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sig = b'\x89\x50\x4E\x47\x0D\x0A\x1A\x0A'
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index = data.find(sig)
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if index != -1:
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print('[x] 检测到文件头前有垃圾数据，已尝试修复')
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head = data[:index]
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data = data[index:]
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changed = True
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elif data[0:8] != sig:
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print('[x] 检测到文件头异常，已尝试修复')
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data[0:8] = sig
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changed = True
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return changed, data, head
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# 修复尺寸
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@staticmethod
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def repair_size(data: bytearray):
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changed = False
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print('[*] 检测文件尺寸')
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chunk_begin = 8
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width_begin = chunk_begin + 8
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height_begin = chunk_begin + 12
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length = int.from_bytes(data[chunk_begin:chunk_begin+4], byteorder='big')
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chunk_data = data[chunk_begin+4: chunk_begin+4+length]
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ctype = chunk_data[0:4] # 应该为 b'\x49\x48\x44\x52'，即 b'IHDR'
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width = int.from_bytes(chunk_data[4:8], byteorder='big')
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height = int.from_bytes(chunk_data[8:12], byteorder='big')
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crc = chunk_data[-4:]
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if GIF.test_ihdr_chunk(chunk_data[:-4], crc):
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print(' - 图片尺寸设置正确')
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else:
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if width == 0:
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print('[x] 检测到图片宽度设置异常，尝试修复...')
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for i in range(1, 2048):
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chunk_data[4:8] = i.to_bytes(4, byteorder='big')
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if GIF.test_ihdr_chunk(chunk_data[:-4], crc):
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width = i
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print(f'[*] 图片宽度修复成功，宽度值为{i}')
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data[width_begin: width_begin+4] = width.to_bytes(4, byteorder='big')
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changed = True
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break
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if width == 0:
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print('[x] 图片宽度修复失败')
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temp = input(f'当前宽度值为{width}，高度值为{height}，是否尝试将高度值设置为更高？可输入高度值或直接回车：')
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if temp.isdigit():
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height = int(temp)
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data[height_begin: height_begin+4] = height.to_bytes(4, byteorder='big')
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print(f'[*] 已将图片高度设置为{height}')
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changed = True
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return changed, data
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@staticmethod
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def test_ihdr_chunk(chunk_data, crc):
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crc32 = binascii.crc32(chunk_data) & 0xffffffff
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return crc32 == crc
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types = [PNG] # 暂时先只处理PNG，其他的都没写好呢[PNG, JPG, GIF]
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def check_image_type(filename: str, data: bytearray):
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file_type1 = None
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if re.match('.*\.png$', filename.lower()):
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file_type1 = 'png'
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elif re.match('.*\.jpg$', filename.lower()):
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file_type1 = 'jpg'
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elif re.match('.*\.gif$', filename.lower()):
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file_type1 = 'gif'
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for model in types:
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if re.match(f'.*\.{model.extension}$', filename.lower()):
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file_type1 = model
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break
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file_type2 = None
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weight = 0
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weight2 = PNG.test(data)
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if weight2 > weight:
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file_type2 = 'png'
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weight = weight2
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weight2 = JPG.test(data)
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if weight2 > weight:
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file_type2 = 'jpg'
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weight = weight2
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weight2 = GIF.test(data)
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if weight2 > weight:
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file_type2 = 'gif'
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weight = weight2
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for model in types:
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weight2 = model.test(data)
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if weight2 > weight:
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file_type2 = model
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weight = weight2
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if file_type1 != None:
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if file_type1 == file_type2:
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print(f'看起来文件格式是{file_type1}')
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print(f'看起来文件格式是{file_type1.extension}')
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else:
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print(f'文件名中格式是{file_type1}，但是解析文件头格式发现{weight}%是{file_type2}')
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print(f'文件名中格式是{file_type1.extension}，但是解析文件头格式发现{weight}%是{file_type2.extension}')
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else:
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if file_type2 != None:
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file_type1 = file_type2
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print(f'检测文件头认为文件格式{weight}%是{file_type2}')
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print(f'检测文件头认为文件格式{weight}%是{file_type2.extension}')
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else:
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print('未检测到任何图片格式特征，该文件可能不是图片文件')
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index = input('要指定文件格式吗？或者直接回车。(1、png 2、jpg 3、gif)：')
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for i in range(len(types)):
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print(f' {i}、{types[i].extension}')
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index = input('要指定文件格式吗？或者直接回车。请输入文件格式序号：')
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if index.isdigit():
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index = int(index)
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if index == 1:
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file_type1 = 'png'
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elif index == 2:
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file_type1 = 'jpg'
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elif index == 3:
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file_type1 = 'gif'
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file_type1 = types[index]
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return file_type1
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@ -358,14 +59,7 @@ def main(filename: str):
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data = bytearray(f.read())
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# 确定文件格式
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file_type = check_image_type(filename, data)
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model = None
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if file_type == 'png':
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model = PNG
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elif file_type == 'jpg':
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model = JPG
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elif file_type == 'gif':
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model = GIF
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model = check_image_type(filename, data)
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# 检测并修复
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changed = False
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@ -375,6 +69,16 @@ def main(filename: str):
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changed1, data, tail = model.check_tail(data)
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changed2, data, head = model.repair_sig(data)
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changed3, data, width, height = model.repair_size(data)
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changed4, data, data_append = model.check_data(data)
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checked_channel = False # 是否检测过RGB通道，如果没检测过，则下面还会尝试检测一遍
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try:
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# 尝试分析通道信息
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changed5, data_r, data_g, data_b = model.check_channels(filename, width, height)
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checked_channel = True
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except Exception as e:
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pass
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#print('[x] 尝试打开图片失败，失败原因：' + str(e))
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changed = changed1 or changed2 or changed3
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else:
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print('[*] 未进行任何处理')
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@ -399,9 +103,16 @@ def main(filename: str):
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f = open(os.path.join(dirpath, 'head'), 'wb')
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f.write(head)
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f.close()
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for i in range(len(data_append)):
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f = open(os.path.join(dirpath, 'data_append_' + str(i)), 'wb')
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f.write(data_append[i])
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f.close()
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print(f'[*] 分析结果已保存到 {dirpath}')
|
||||
# 尝试打开图片看一看
|
||||
if not checked_channel:
|
||||
# 尝试分析通道信息
|
||||
changed5, data_r, data_g, data_b = model.check_channels(imagepath, width, height)
|
||||
try:
|
||||
# 尝试打开图片看一看
|
||||
im = Image.open(imagepath)
|
||||
im.show()
|
||||
except Exception as e:
|
||||
|
|
@ -412,6 +123,7 @@ def main(filename: str):
|
|||
print('[*] 分析完成！')
|
||||
|
||||
# 开始执行
|
||||
filename = sys.argv[1]
|
||||
# filename = 'G:\\1.png'
|
||||
if len(sys.argv) > 1:
|
||||
filename = sys.argv[1]
|
||||
|
||||
main(filename)
|
||||
|
|
|
|||
|
|
@ -0,0 +1,92 @@
|
|||
import binascii
|
||||
|
||||
|
||||
class GIF:
|
||||
extension = 'gif'
|
||||
|
||||
def __init__(self):
|
||||
pass
|
||||
|
||||
# 检测文件格式，返回百分比
|
||||
@staticmethod
|
||||
def test(data: bytearray):
|
||||
return 100
|
||||
|
||||
# 获取图片信息
|
||||
@staticmethod
|
||||
def get_info(data: bytearray):
|
||||
info = {}
|
||||
return info
|
||||
|
||||
def check_tail(data: bytearray):
|
||||
changed = False
|
||||
tail = None
|
||||
return changed, data, tail
|
||||
|
||||
# 修复文件头
|
||||
@staticmethod
|
||||
def repair_sig(data: bytearray):
|
||||
changed = False
|
||||
head = None
|
||||
print('[*] 检测文件头')
|
||||
sig = b'\x89\x50\x4E\x47\x0D\x0A\x1A\x0A'
|
||||
index = data.find(sig)
|
||||
if index != -1:
|
||||
print('[x] 检测到文件头前有垃圾数据，已尝试修复')
|
||||
head = data[:index]
|
||||
data = data[index:]
|
||||
changed = True
|
||||
elif data[0:8] != sig:
|
||||
print('[x] 检测到文件头异常，已尝试修复')
|
||||
data[0:8] = sig
|
||||
changed = True
|
||||
return changed, data, head
|
||||
|
||||
# 修复尺寸
|
||||
@staticmethod
|
||||
def repair_size(data: bytearray):
|
||||
changed = False
|
||||
print('[*] 检测文件尺寸')
|
||||
chunk_begin = 8
|
||||
width_begin = chunk_begin + 8
|
||||
height_begin = chunk_begin + 12
|
||||
length = int.from_bytes(data[chunk_begin:chunk_begin+4], byteorder='big')
|
||||
chunk_data = data[chunk_begin+4: chunk_begin+4+length]
|
||||
ctype = chunk_data[0:4] # 应该为 b'\x49\x48\x44\x52'，即 b'IHDR'
|
||||
width = int.from_bytes(chunk_data[4:8], byteorder='big')
|
||||
height = int.from_bytes(chunk_data[8:12], byteorder='big')
|
||||
crc = chunk_data[-4:]
|
||||
|
||||
if GIF.test_ihdr_chunk(chunk_data[:-4], crc):
|
||||
print(' - 图片尺寸设置正确')
|
||||
else:
|
||||
if width == 0:
|
||||
print('[x] 检测到图片宽度设置异常，尝试修复...')
|
||||
for i in range(1, 2048):
|
||||
chunk_data[4:8] = i.to_bytes(4, byteorder='big')
|
||||
if GIF.test_ihdr_chunk(chunk_data[:-4], crc):
|
||||
width = i
|
||||
print(f'[*] 图片宽度修复成功，宽度值为{i}')
|
||||
data[width_begin: width_begin+4] = width.to_bytes(4, byteorder='big')
|
||||
changed = True
|
||||
break
|
||||
if width == 0:
|
||||
print('[x] 图片宽度修复失败')
|
||||
|
||||
temp = input(f'当前宽度值为{width}，高度值为{height}，是否尝试将高度值设置为更高？可输入高度值或直接回车：')
|
||||
if temp.isdigit():
|
||||
height = int(temp)
|
||||
data[height_begin: height_begin+4] = height.to_bytes(4, byteorder='big')
|
||||
print(f'[*] 已将图片高度设置为{height}')
|
||||
changed = True
|
||||
return changed, data
|
||||
|
||||
@staticmethod
|
||||
def test_ihdr_chunk(chunk_data, crc):
|
||||
crc32 = binascii.crc32(chunk_data) & 0xffffffff
|
||||
return crc32 == crc
|
||||
|
||||
@staticmethod
|
||||
def check_data(data: bytearray):
|
||||
return False, data, []
|
||||
|
||||
|
|
@ -0,0 +1,99 @@
|
|||
import binascii
|
||||
|
||||
|
||||
class JPG:
|
||||
extension = 'jpg'
|
||||
|
||||
def __init__(self):
|
||||
pass
|
||||
|
||||
# 检测文件格式，返回百分比
|
||||
@staticmethod
|
||||
def test(data: bytearray):
|
||||
rate = 0
|
||||
if data.find(b'\xff\x') != -1:
|
||||
rate = 100
|
||||
else:
|
||||
if data.find(b'IHDR') != -1:
|
||||
rate = rate + 30
|
||||
if data.find(b'IEND') != -1:
|
||||
rate = rate + 30
|
||||
return rate
|
||||
|
||||
# 获取图片信息
|
||||
@staticmethod
|
||||
def get_info(data: bytearray):
|
||||
info = {}
|
||||
return info
|
||||
|
||||
def check_tail(data: bytearray):
|
||||
changed = False
|
||||
tail = None
|
||||
return changed, data, tail
|
||||
|
||||
# 修复文件头
|
||||
@staticmethod
|
||||
def repair_sig(data: bytearray):
|
||||
changed = False
|
||||
head = None
|
||||
print('[*] 检测文件头')
|
||||
sig = b'\x89\x50\x4E\x47\x0D\x0A\x1A\x0A'
|
||||
index = data.find(sig)
|
||||
if index != -1:
|
||||
print('[x] 检测到文件头前有垃圾数据，已尝试修复')
|
||||
head = data[:index]
|
||||
data = data[index:]
|
||||
changed = True
|
||||
elif data[0:8] != sig:
|
||||
print('[x] 检测到文件头异常，已尝试修复')
|
||||
data[0:8] = sig
|
||||
changed = True
|
||||
return changed, data, head
|
||||
|
||||
# 修复尺寸
|
||||
@staticmethod
|
||||
def repair_size(data: bytearray):
|
||||
changed = False
|
||||
print('[*] 检测文件尺寸')
|
||||
chunk_begin = 8
|
||||
width_begin = chunk_begin + 8
|
||||
height_begin = chunk_begin + 12
|
||||
length = int.from_bytes(data[chunk_begin:chunk_begin+4], byteorder='big')
|
||||
chunk_data = data[chunk_begin+4: chunk_begin+4+length]
|
||||
ctype = chunk_data[0:4] # 应该为 b'\x49\x48\x44\x52'，即 b'IHDR'
|
||||
width = int.from_bytes(chunk_data[4:8], byteorder='big')
|
||||
height = int.from_bytes(chunk_data[8:12], byteorder='big')
|
||||
crc = chunk_data[-4:]
|
||||
|
||||
if JPG.test_ihdr_chunk(chunk_data[:-4], crc):
|
||||
print(' - 图片尺寸设置正确')
|
||||
else:
|
||||
if width == 0:
|
||||
print('[x] 检测到图片宽度设置异常，尝试修复...')
|
||||
for i in range(1, 2048):
|
||||
chunk_data[4:8] = i.to_bytes(4, byteorder='big')
|
||||
if JPG.test_ihdr_chunk(chunk_data[:-4], crc):
|
||||
width = i
|
||||
print(f'[*] 图片宽度修复成功，宽度值为{i}')
|
||||
data[width_begin: width_begin+4] = width.to_bytes(4, byteorder='big')
|
||||
changed = True
|
||||
break
|
||||
if width == 0:
|
||||
print('[x] 图片宽度修复失败')
|
||||
|
||||
temp = input(f'当前宽度值为{width}，高度值为{height}，是否尝试将高度值设置为更高？可输入高度值或直接回车：')
|
||||
if temp.isdigit():
|
||||
height = int(temp)
|
||||
data[height_begin: height_begin+4] = height.to_bytes(4, byteorder='big')
|
||||
print(f'[*] 已将图片高度设置为{height}')
|
||||
changed = True
|
||||
return changed, data
|
||||
|
||||
@staticmethod
|
||||
def test_ihdr_chunk(chunk_data, crc):
|
||||
crc32 = binascii.crc32(chunk_data) & 0xffffffff
|
||||
return crc32 == crc
|
||||
|
||||
@staticmethod
|
||||
def check_data(data: bytearray):
|
||||
return False, data, []
|
||||
|
|
@ -0,0 +1,238 @@
|
|||
import binascii
|
||||
import zlib
|
||||
from PIL import Image
|
||||
|
||||
class PNG:
|
||||
extension = 'png'
|
||||
sig = b'\x89\x50\x4E\x47\x0D\x0A\x1A\x0A'
|
||||
|
||||
def __init__(self):
|
||||
pass
|
||||
|
||||
# 检测文件格式，返回百分比
|
||||
@staticmethod
|
||||
def test(data: bytearray):
|
||||
rate = 0
|
||||
if data.find(PNG.sig) != -1:
|
||||
rate = 100
|
||||
else:
|
||||
if data.find(b'IHDR') != -1:
|
||||
rate = rate + 30
|
||||
if data.find(b'IEND') != -1:
|
||||
rate = rate + 30
|
||||
return rate
|
||||
|
||||
# 获取图片信息
|
||||
@staticmethod
|
||||
def get_info(data: bytearray):
|
||||
text = b'tEXt'
|
||||
index = data.find(text)
|
||||
chunk_data = ''
|
||||
if index > 32:
|
||||
length = int.from_bytes(data[index-4: index], byteorder='big')
|
||||
chunk_data = data[index+4: index+4+length]
|
||||
print('[*] 图像信息：')
|
||||
print(bytes(chunk_data).split(b'\x00'))
|
||||
|
||||
info = chunk_data
|
||||
return info
|
||||
|
||||
def check_tail(data: bytearray):
|
||||
changed = False
|
||||
tail = None
|
||||
iend = b'\x49\x45\x4E\x44\xAE\x42\x60\x82'
|
||||
length = len(data)
|
||||
index = data.find(iend)
|
||||
if index == -1:
|
||||
index = data.find(iend[0:4])
|
||||
if index != -1:
|
||||
index = index + 4
|
||||
else:
|
||||
index = index + 8
|
||||
|
||||
if index == -1:
|
||||
print('[x] 缺少png文件格式结束标识符IEND')
|
||||
elif index < 32:
|
||||
print('[x] 缺少png文件格式结束标识符IEND位置貌似不太对')
|
||||
else:
|
||||
tail = data[index:]
|
||||
if len(tail) > 0:
|
||||
changed = True
|
||||
print('[x] 检测到文件尾部有垃圾数据，已尝试修复')
|
||||
|
||||
return changed, data, tail
|
||||
|
||||
# 修复文件头
|
||||
@staticmethod
|
||||
def repair_sig(data: bytearray):
|
||||
changed = False
|
||||
head = None
|
||||
print('[*] 检测文件头')
|
||||
index = data.find(PNG.sig)
|
||||
if index > 0:
|
||||
# 如果能检测到文件头
|
||||
print('[x] 检测到文件头前有垃圾数据，已尝试修复')
|
||||
head = bytes(data[:index])
|
||||
data = data[index:]
|
||||
changed = True
|
||||
elif data[0:8] != PNG.sig:
|
||||
# 如果检测不到文件头，那么需要进一步确认有没有可能是被篡改或者缺失文件头，可以根据下一个chunk标记来辅助确认
|
||||
index2 = data.find(b'IHDR')
|
||||
if index2 != -1:
|
||||
# 能检测到有图片尺寸信息的IHDR标记
|
||||
if index2 == 12:
|
||||
# 说明文件头只是写的不对，直接替换
|
||||
data[0:8] = PNG.sig
|
||||
elif index2 > 12:
|
||||
# 说明前面还是有垃圾数据
|
||||
head = bytes(data[:index2-4])
|
||||
data = bytearray(PNG.sig) + data[index2-4:]
|
||||
print('[x] 检测到文件头前有垃圾数据，已尝试修复')
|
||||
elif index2 > 3 and index2 < 12:
|
||||
# 说明文件头长度不够
|
||||
data = bytearray(PNG.sig) + data[index2-4:]
|
||||
print('[*] 检测到文件头异常，已尝试修复')
|
||||
changed = True
|
||||
else:
|
||||
# 说明可能不是png图片了
|
||||
print('[x] 未发现png图片特征，无法修复')
|
||||
return changed, data, head
|
||||
|
||||
# 修复尺寸
|
||||
@staticmethod
|
||||
def repair_size(data: bytearray):
|
||||
changed = False
|
||||
print('[*] 检测文件尺寸')
|
||||
chunk_begin = 8
|
||||
data_begin = chunk_begin + 8
|
||||
width_begin = data_begin
|
||||
height_begin = data_begin + 4
|
||||
length = int.from_bytes(data[chunk_begin:chunk_begin+4], byteorder='big')
|
||||
ctype = data[chunk_begin+4: chunk_begin+8] # 应该为 b'\x49\x48\x44\x52'，即 b'IHDR'
|
||||
chunk_data = data[data_begin: data_begin+length]
|
||||
width = int.from_bytes(chunk_data[0:4], byteorder='big')
|
||||
height = int.from_bytes(chunk_data[4:8], byteorder='big')
|
||||
crc = int.from_bytes(data[data_begin+length:data_begin+length+4], byteorder='big')
|
||||
|
||||
if PNG.test_ihdr_chunk(ctype + chunk_data, crc):
|
||||
print(' - 图片尺寸设置正确')
|
||||
else:
|
||||
b = False
|
||||
if not b:
|
||||
print('[x] 尝试修复图片宽度...')
|
||||
chunk = ctype + chunk_data
|
||||
for i in range(1, 2048):
|
||||
chunk[4:8] = i.to_bytes(4, byteorder='big')
|
||||
if PNG.test_ihdr_chunk(bytes(chunk), crc):
|
||||
width = i
|
||||
print(f'[*] 图片宽度修复成功，宽度值为{i}')
|
||||
data[width_begin: width_begin+4] = width.to_bytes(4, byteorder='big')
|
||||
changed = True
|
||||
b = True
|
||||
break
|
||||
if not b:
|
||||
print('[x] 尝试修复图片高度...')
|
||||
chunk = ctype + chunk_data
|
||||
for i in range(1, 2048):
|
||||
chunk[8:12] = i.to_bytes(4, byteorder='big')
|
||||
if PNG.test_ihdr_chunk(chunk, crc):
|
||||
height = i
|
||||
print(f'[*] 图片高度修复成功，宽度值为{i}')
|
||||
data[height_begin: height_begin+4] = width.to_bytes(4, byteorder='big')
|
||||
changed = True
|
||||
b = True
|
||||
break
|
||||
if not b:
|
||||
temp = input(f'当前宽度值为{width}，高度值为{height}，是否尝试将高度值设置为更高？可输入高度值或直接回车：')
|
||||
if temp.isdigit():
|
||||
height = int(temp)
|
||||
data[height_begin: height_begin+4] = height.to_bytes(4, byteorder='big')
|
||||
print(f'[*] 已将图片高度设置为{height}')
|
||||
changed = True
|
||||
return changed, data, width, height
|
||||
|
||||
@staticmethod
|
||||
def test_ihdr_chunk(chunk_data, crc):
|
||||
crc32 = binascii.crc32(chunk_data) & 0xffffffff
|
||||
return crc32 == crc
|
||||
|
||||
@staticmethod
|
||||
def check_data(data: bytearray):
|
||||
idats = []
|
||||
index = 0
|
||||
print('[*] 检测IDAT数据块')
|
||||
while True:
|
||||
index = data.find(b'IDAT', index)
|
||||
if index != -1:
|
||||
length = int.from_bytes(data[index-4: index], byteorder='big')
|
||||
data_begin = index + 4
|
||||
idats.append((data_begin, length))
|
||||
index = index + length + 8
|
||||
else:
|
||||
break
|
||||
|
||||
changed = False
|
||||
b = False
|
||||
idat_append = []
|
||||
for idat in idats:
|
||||
if not b:
|
||||
# 默认每个IDAT数据块最大为65445，如果出现一个数据块小于65445，说明数据块结束。如果后续又出现了IDAT数据块，则说明可能有异常数据
|
||||
if idat[1] < 65445:
|
||||
b = True
|
||||
else:
|
||||
print('[x] 检测到异常IDAT数据块')
|
||||
idat_data = data[idat[0]: idat[0]+idat[1]]
|
||||
idat_result = binascii.hexlify(zlib.decompress(idat_data)) # 究竟是不是要这样处理有待研究
|
||||
idat_append.append[idat_result]
|
||||
|
||||
return changed, data, idat_append
|
||||
|
||||
# 处理RGB三个通道
|
||||
@staticmethod
|
||||
def check_channels(filename: str, width: int, height: int):
|
||||
image = Image.open(filename)
|
||||
pixels_r = []
|
||||
pixels_g = []
|
||||
pixels_b = []
|
||||
for y in range(height):
|
||||
for x in range(width):
|
||||
r, g, b = image.getpixel((x, y))
|
||||
pixels_r.append(r)
|
||||
pixels_g.append(g)
|
||||
pixels_b.append(b)
|
||||
|
||||
data_r = PNG.check_channel(pixels_r, width, height, '红')
|
||||
data_g = PNG.check_channel(pixels_g, width, height, '绿')
|
||||
data_b = PNG.check_channel(pixels_b, width, height, '蓝')
|
||||
|
||||
return False, data_r, data_g, data_b
|
||||
|
||||
# 对单通道的处理方式
|
||||
@staticmethod
|
||||
def check_channel(channel: bytearray, width: int, height: int, channel_name):
|
||||
data_set = set(channel)
|
||||
value_len = len(data_set)
|
||||
|
||||
print('[*] 正在检测%s色通道'%channel_name)
|
||||
|
||||
# value_len为1说明所有像素都一样，不包含任何信息
|
||||
if value_len == 1:
|
||||
return False
|
||||
|
||||
# value_len小于17说明有可能包含01的二进制信息，或者8、10、16进制信息
|
||||
if value_len < 17:
|
||||
print('[?] 通道颜色值仅有' + str(value_len) + '个值, 建议继续分析此通道信息')
|
||||
|
||||
# 说明应该不只是黑白信息，可能都为可打印字符
|
||||
if value_len > 2 and value_len < 95:
|
||||
# 提取出可打印字符
|
||||
print_list = [chr(i) for i in channel if i > 31 and i < 127]
|
||||
print_str = ''.join(print_list)
|
||||
print('[?] 看看通道中这些可打印信息有没有用吧：' + print_str)
|
||||
return print_str
|
||||
|
||||
return False
|
||||
|
||||
|
||||
|
||||
|
||||
Loading…
Reference in New Issue