1500字范文 > 祥云杯网络安全大赛 MISC Writeup

祥云杯网络安全大赛 MISC Writeup

时间：2024-07-04 10:07:28

文章目录

签到进制反转到点了xixixi带音乐家Charles Sensor

签到

PS C:\Users\Administrator> php -r "var_dump(base64_decode('ZmxhZ3txcV9ncm91cF84MjY1NjYwNDB9'));"string(24) "flag{qq_group_826566040}"

进制反转

题目描述：

电脑中到底使用的是什么进制呢？真是麻烦，有时候还是手机好用。结果用flag{}包住，并且全为大写

WinRAR打开显示文件头损坏，其次有加密，猜测RAR伪加密，使用010 Editor打开

文件结尾发现提示：flag is the song's name

接着找到第三块struct RarBlock block[0]下的struct FileHeadFlags HEAD_FLAGS

修改ubyte PASSWORD_ENCRYPTED的值为0

解压得到flag.wav，无法使用Audacity打开，就通过导入文件->导入->原始数据

听着很明显是歌声但是却是倒放，Ctrl+A全选，点击效果 > 反向(时间)，然后再效果 > 改变速率，调节到一个正常歌曲的播放速度，然后经过降噪，消除咔嚓声等一系列操作，最后听歌识别

先推个在线识别歌曲网站：/identify-songs-music-recognition-online/

听歌识曲识别不出来，就听歌词找吧，也挺快的，考验听力水平

歌名：《Too Good At Goodbyes》

flag{TOOGOODATGOODBYES}

到点了

题目描述：

我那么多遗憾，那么多期盼，你知道吗（下雨熊猫头

1.docx打开，勾选隐藏文字

2.docx有加密，根据1.docx提供的提示，使用Accent OFFICE Password Recovery爆破密码

先尝试爆破8位纯数字，毕竟8位字母数字就太多了，还不知道分不分大小写

爆破过程就不看了，时间太长了，直接贴结果，密码为：2024

解开2.docx，全选标红，发现有一串AB字符，很明显应该是培根密码

AABBAABBBAABBBAAAABBABBABABAAAAABBAAABBBBAABBBAABABABBAAABAAAABAABAABBABAAAAABAA

培根在线解码：/peigen/

GOODNIGHTSWEETIEgoodnightsweetie

binwalk分离3.docx，得到一个4.zip，里面有一张4.bmp

4.bmp

bmp隐写，有密码，试了不是LSB，尝试使用wbs43open

密码：goodnightsweetie

flag{2ec9405ac7bcfb16f5fd494bcf21337c}

xixixi

题目描述：

室友最近沉迷y神，又氪又肝，还ghs。为了他的身体着想，我把他的s图整没了。但我明明删了脚本啊，为什么还能被他发现......8说了，医院的空调真舒服~

new.vhd

可以使用DiskGenius或者Win7的磁盘管理进行挂载，建议使用DiskGenius挂载

DiskGenius->磁盘->打开虚拟磁盘文件

kejin.png

以及还有两个Py脚本

import structclass FAT32Parser(object):def __init__(self, vhdFileName):with open(vhdFileName, 'rb') as f:self.diskData = f.read()self.DBR_off = self.GetDBRoff()self.newData = ''.join(self.diskData)def GetDBRoff(self):DPT_off = 0x1BEtarget = self.diskData[DPT_off+8:DPT_off+12]DBR_sector_off, = struct.unpack("<I", target)return DBR_sector_off * 512def GetFAT1off(self):target = self.diskData[self.DBR_off+0xE:self.DBR_off+0x10]FAT1_sector_off, = struct.unpack("<H", target)return self.DBR_off + FAT1_sector_off * 512def GetFATlength(self):target = self.diskData[self.DBR_off+0x24:self.DBR_off+0x28]FAT_sectors, = struct.unpack("<I", target)return FAT_sectors * 512def GetRootoff(self):FAT_length = self.GetFATlength()FAT2_off = self.GetFAT1off() + FAT_lengthreturn FAT2_off + FAT_lengthdef Cluster2FAToff(self, cluster):FAT1_off = self.GetFAT1off()return FAT1_off + cluster * 4def Cluster2DataOff(self, cluster):rootDir_off = self.GetRootoff()return rootDir_off + (cluster - 2) * 512

import structfrom xixi import FAT32Parserfrom xixixi import Padding, picDepartListdef EncodePieces():global clusterListres = []Range = len(picDepartList) # 58# GetRandomClusterList(n) - Generate a random cluster list with length nclusterList = GetRandomClusterList(Range)for i in range(Range):if i != Range - 1:newCRC = struct.pack("<I", clusterList[i+1])plainData = picDepartList[i][:-4] + newCRCelse:plainData = picDepartList[i]# Show the first piece to him, hhhif i == 0:newPiece = plainDataelse:newPiece = ''key = clusterList[i] & 0xFEfor j in plainData:newPiece += chr(ord(j) ^ key)# Padding() -- Fill to an integral multiple of 512 with \xFFres.append(Padding(newPiece))return res

参考上面给出的脚本进行还原，还原脚本参考的是Timeline Sec团队的脚本

原文地址：https://mp./s/CP3-W8VcLokQNYMSbXw9wg

# -*- coding: utf-8 -*-# @Project: Hello Python!# @File : exp# @Author : Tr0jAn <Tr0jAn@># @Date : -11-22import structimport binasciiclass FAT32Parser(object):def __init__(self, vhdFileName):with open(vhdFileName, 'rb') as f:self.diskData = f.read()self.DBR_off = self.GetDBRoff()self.newData = ''.join(str(self.diskData))def GetDBRoff(self):DPT_off = 0x1BEtarget = self.diskData[DPT_off+8:DPT_off+12]DBR_sector_off, = struct.unpack("<I", target)return DBR_sector_off * 512def GetFAT1off(self):target = self.diskData[self.DBR_off+0xE:self.DBR_off+0x10]FAT1_sector_off, = struct.unpack("<H", target)return self.DBR_off + FAT1_sector_off * 512def GetFATlength(self):target = self.diskData[self.DBR_off+0x24:self.DBR_off+0x28]FAT_sectors, = struct.unpack("<I", target)return FAT_sectors * 512def GetRootoff(self):FAT_length = self.GetFATlength()FAT2_off = self.GetFAT1off() + FAT_lengthreturn FAT2_off + FAT_lengthdef Cluster2FAToff(self, cluster):FAT1_off = self.GetFAT1off()return FAT1_off + cluster * 4def Cluster2DataOff(self, cluster):rootDir_off = self.GetRootoff()return rootDir_off + (cluster - 2) * 512def read(n):global keybinary = b''for i in vhd.read(n):binary += (i ^ (key & 0xFE)).to_bytes(length=1, byteorder='big', signed=False)return binaryFAT = FAT32Parser("new.vhd")vhd = open("new.vhd", "rb")vhd.seek(0x27bae00) # 定位磁盘中图片位置flag = open("flag.png", "wb")flag.write(vhd.read(8)) # 写入png头key = 0while True:d = read(8)length, cType = struct.unpack(">I4s", d)print(length, cType) # length为数据长度，cType为数据块类型data = read(length)CRC = struct.unpack(">I", read(4))[0]print(CRC)rCRC = binascii.crc32(cType + data) & 0xffffffffprint(rCRC)rDATA = struct.pack(">I", length) + cType + data + struct.pack(">I", rCRC)flag.write(rDATA)if CRC != rCRC: # CRC错误的IDAT数据块b_endian = struct.pack(">I", CRC)clusterList = struct.unpack("<I", b_endian)[0]print(clusterList)vhd.seek(FAT.Cluster2DataOff(clusterList))key = clusterList & 0xFEif cType == b"IEND":break

flag{0cfdd1ad80807da6c0413de606bb0ae4}