phpwcms 1.7.9 Code Execution
Posted on 10 December 2015
Security Advisory - Curesec Research Team 1. Introduction Affected Product: phpwcms 1.7.9 Fixed in: 1.8.0 RC1 Fixed Version https://github.com/slackero/phpwcms/archive/ Link: phpwcms-1.8.0-RC1.zip Vendor Website: http://www.phpwcms.de/ Vulnerability Code Execution Type: Remote Yes Exploitable: Reported to 09/29/2015 vendor: Disclosed to 12/02/2015 public: Release mode: Coordinated release CVE: requested, but not assigned Credits Tim Coen of Curesec GmbH 2. Overview phpwcms allows the upload of files with dangerous type, which leads to code execution. Additionally, it allows registered users who are not admins to use PHP tags, which also leads to code execution. Please note that a user account is needed to upload files. The user does not need administration rights, but there is no open registration by default (the form to add users is however open to CSRF). 3. Unrestricted Upload of File with Dangerous Type CVSS High 9.0 AV:N/AC:L/Au:S/C:C/I:C/A:C Description When uploading files, there are no checks as to the type or extension of the file. When uploading single files, these are stored inside the "filearchive" directory. The original file name is changed to the hash of the file name. The directory is protected with a .htaccess file from accessing or executing files directly. Because of this, uploading single files can not easily be exploited; it may however be possible to execute them via include_int_php (see below). However, when uploading multiple files, these are stored temporarily inside the "upload" directory, and these files are not renamed. The "upload" directory is also protected by an .htaccess file, but as .htaccess files can be uploaded, it can be overwritten, thus leading to code execution. Please note that a user account is needed to upload files. The user does not need administration rights, but there is no open registration by default. Proof of Concept Upload a .htaccess file and a PHP file here: http://localhost/phpwcms-phpwcms-1.7.9/phpwcms.php?do=files&p=8 The .htaccess file should contain: allow from all Now the uploaded PHP file can be accessed and executed: http://localhost/phpwcms-phpwcms-1.7.9/upload/shell.php?x=id 4. Code Execution CVSS High 9.0 AV:N/AC:L/Au:S/C:C/I:C/A:C Description The functions include_int_php, include_int_phpcode, and include_ext_php can all be used to gain code execution. These functions can be used by any logged in user, admin rights are not required. Proof of Concept Create a new article. As author, use [PHP] passthru("touch mynewtest.php") [/PHP] Visiting http://localhost/phpwcms-phpwcms-1.7.9/feeds.php is one of the ways to trigger the code execution. Please note that the feed is by default cached for one hour, during which the code would not be executed as the cache is loaded instead. The vulnerable functions are used in other places as well, which means an attacker may not have to wait an hour for the cache to clear by triggering the code elsewhere. 5. Solution To mitigate this issue please upgrade at least to version 1.8.0 RC1: https://github.com/slackero/phpwcms/archive/phpwcms-1.8.0-RC1.zip Please note that a newer version might already be available. 6. Report Timeline 09/29/2015 Informed Vendor about Issue 09/29/2015 Vendor confirmed issues 10/21/2015 Reminded Vendor of Disclosure Date 10/25/2015 Vendor requests more time 11/17/2015 CVE Requested (no reply) 11/24/2015 Reminded Vendor of Disclosure Date 11/29/2015 Vendor releases fix 12/02/2015 Disclosed to public Blog Reference: https://blog.curesec.com/article/blog/phpwcms-179-Code-Execution-122.html -- blog: https://blog.curesec.com tweet: https://twitter.com/curesec Curesec GmbH Curesec Research Team Romain-Rolland-Str 14-24 13089 Berlin, Germany
