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#攻擊標題：uWSGI PHP Plugin目錄遍歷

#日期：2018年3月1日

#開發作者：Marios Nicolaides-RUNESEC

#評審人：西蒙·洛伊齊德斯和尼古拉斯·馬基塔尼斯-魯內塞克

#供應商主頁：https://uwsgi-docs.readthedocs.io

#受影響的軟件：2.0.17之前的uWSGI PHP Plugin

#測試依據：uWSGI 2.0.12和2.0.15

#公司代碼：CVE-2018-7490

#類別：Web應用程序

概述

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在沒有指定“PHP allowed docroot”選項的情況下，2.0.17之前的uWSGI PHP插件容易被目錄遍歷。

該漏洞是由于請求通過“php docroot”指定的DOCUMENT_ROOT目錄下的資源時對文件路徑的驗證不正確造成的。

遠程攻擊者可以利用此漏洞，使用路徑遍歷序列（“..%2f”）從易受攻擊的系統中讀取任意文件。

這在uWSGI 2.0.12和2.0.15上進行了測試。2.0.17之前的所有版本都會受到影響。

細節

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uWSGI的文檔指出，phpdocroot選項用于將我們的php環境囚禁在一個項目目錄中(http://uwsgi docs.readthedocs.io/en/latest/PHP.html\run-php-apps-without-a-frontend-server）。

；將我們的php環境囚禁在project_dir中

php docroot=%（項目目錄）

在測試過程中，觀察到uWSGI在作為獨立（沒有前端web服務器）執行時受到目錄遍歷漏洞的影響，同時使用“php docroot”選項來強制web應用程序的DOCUMENT_ROOT。

uwsgi--http套接字：1337--protocol=http--plugin php--php索引索引.php--php docroot/home/testing/webapp/

攻擊者可以通過使用路徑遍歷序列（“…%2f”）訪問敏感信息來攻擊此漏洞，如下所示：

http://example.runesec.com%2f….%2f….%2f….%2f/

我們注意到，當執行目錄遍歷攻擊時，uWSGI發出以下安全錯誤：

[uwsgi fileserve]安全錯誤：/etc/passwd不在/home/testing/webapp下或安全路徑下

但是，請求文件的內容（即/etc/passwd）仍然返回給用戶。

在搜索了web上可能的解決方案之后，我們注意到“php-allowed-docroot”選項以前被添加到uWSGI中，以獲得更好的安全性，并且可以用來列出允許的文檔根，但是沒有進一步的細節(http://lists.unbit.it/pipermail/uwsgi/2011-December/003180.html).

在進一步的測試中，我們發現當使用“php allowed docroot”而不是“php docroot”選項時，它不受目錄遍歷攻擊的影響。

uwsgi--http套接字：1337--protocol=http--plugin php--php索引索引.php--允許的根目錄/php/webapp測試/

在與uWSGI項目進行了一次非常有建設性和有幫助的談話之后，他們發布了一個更新，在使用“php docroot”選項來防止目錄遍歷攻擊時，強制執行文檔根檢查。請參閱緩解部分了解更多信息。

影響

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攻擊者可以利用此漏洞獲取對位于web根目錄之外的敏感文件的未經授權的讀取權限。

緩解

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建議更新至uWSGI 2.0.17-https://uwsgi-docs.readthedocs.io/en/latest/Changelog-2.0.17.html

參考文獻

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https://blog.runesec.com/2018/03/01/uwsgi-path-traversal/

https://uwsgi-docs.readthedocs.io/en/latest/Changelog-2.0.17.html

https://cve.mitre.org/cgi-bin/cvename.cgi？名稱=CVE-2018-7490

https://nvd.nist.gov/vuln/detail/CVE-2018-7490

https://www.owasp.org/index.php/Testing_Directory_traversal/file_include_（OTG-AUTHZ-001）

時間軸

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2017年6月26日-uWSGI項目告知了該問題

2018年2月26日-uWSGI項目發布了一個補丁

2018年3月1日-公開披露

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phpinfo? ?

Server API?

uWSGI

可能會存在。此漏洞

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https://www.exploit-db.com/exploits/44223

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# Exploit Title: uWSGI PHP Plugin Directory Traversal # Date: 01-03-2018 # Exploit Author: Marios Nicolaides - RUNESEC # Reviewers: Simon Loizides and Nicolas Markitanis - RUNESEC # Vendor Homepage: https://uwsgi-docs.readthedocs.io # Affected Software: uWSGI PHP Plugin before 2.0.17 # Tested on: uWSGI 2.0.12 and 2.0.15 # CVE: CVE-2018-7490 # Category: Web ApplicationOVERVIEW -------- The uWSGI PHP plugin before 2.0.17 is vulnerable to Directory Traversal when used without specifying the "php-allowed-docroot" option.The vulnerability exists due to improper validation of the file path when requesting a resource under the DOCUMENT_ROOT directory which is specified via "php-docroot".A remote attacker could exploit this weakness to read arbitrary files from the vulnerable system using path traversal sequences ("..%2f").This was tested on uWSGI 2.0.12 and 2.0.15. All versions before 2.0.17 are affected.DETAILS ------- The documentation of uWSGI states that the php-docroot option is used to jail our php environment to a project directory (http://uwsgi-docs.readthedocs.io/en/latest/PHP.html#run-php-apps-without-a-frontend-server).; jail our php environment to project_dirphp-docroot = %(project_dir)During testing it was observed that uWSGI was affected by a Directory Traversal vulnerability when executed as a standalone (without a front-end web server) along with the "php-docroot" option to enforce the DOCUMENT_ROOT of the web application.uwsgi --http-socket :1337 --protocol=http --plugin php --php-index index.php --php-docroot /home/testing/webapp/An attacker could exploit this vulnerability by using path traversal sequences ("..%2f") to access sensitive information as demonstrated below:http://example.runesec.com:1337/..%2f..%2f..%2f..%2f..%2f..%2f..%2fetc/passwdWe noticed that when a Directory Traversal attack was performed, uWSGI was issuing the following security error:[uwsgi-fileserve] security error: /etc/passwd is not under /home/testing/webapp or a safe pathHowever, the contents of the requested file (i.e., /etc/passwd) were still returned to the user.After searching the web for possible solutions, we noticed that the "php-allowed-docroot" option was previously added to uWSGI for better security and could be used to list the allowed document roots but no further details were available (http://lists.unbit.it/pipermail/uwsgi/2011-December/003180.html).Upon further testing, we observed that when the "php-allowed-docroot" was used instead of the "php-docroot" option, it was not affected by Directory Traversal attacks.uwsgi --http-socket :1337 --protocol=http --plugin php --php-index index.php --php-allowed-docroot /home/testing/webapp/After a very constructive and helpful talk with the uWSGI Project, they released an update which enforces a DOCUMENT_ROOT check when using the "php-docroot" option to prevent Directory Traversal attacks. Please see the MITIGATION section for more information.IMPACT ------ An attacker could exploit this vulnerability to gain unauthorized read access to sensitive files located outside of the web root directory.MITIGATION ---------- It is recommended to update to uWSGI 2.0.17 - https://uwsgi-docs.readthedocs.io/en/latest/Changelog-2.0.17.htmlREFERENCES ---------- https://blog.runesec.com/2018/03/01/uwsgi-path-traversal/ https://uwsgi-docs.readthedocs.io/en/latest/Changelog-2.0.17.html https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-7490 https://nvd.nist.gov/vuln/detail/CVE-2018-7490 https://www.owasp.org/index.php/Testing_Directory_traversal/file_include_(OTG-AUTHZ-001)TIMELINE -------- 26 June 2017 - uWSGI Project informed about the issue 26 February 2018 - uWSGI Project released a patch 1 March 2018 - Exploit publicly disclosed

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