Atutor 2.2 Cross Site Scripting
Posted on 04 February 2016
Security Advisory - Curesec Research Team 1. Introduction Affected Product: Atutor 2.2 Fixed in: partly in ATutor 2.2.1-RC1, complete in 2.2.1 Fixed Version Link: http://www.atutor.ca/atutor/download.php Vendor Website: http://www.atutor.ca/ Vulnerability Type: XSS Remote Exploitable: Yes Reported to vendor: 11/17/2015 Disclosed to public: 02/01/2016 Release mode: Coordinated Release CVE: n/a Credits Tim Coen of Curesec GmbH 2. Overview Atutor is a learning management system (LMS) written in PHP. In version 2.2, it is vulnerable to multiple reflected and persistent XSS attacks. The vulnerabilities can lead to the stealing of cookies, injection of keyloggers, or the bypassing of CSRF protection. If the victim is an admin, a successful exploitation can lead to code execution via the theme uploader, and if the victim is an instructor, this can lead to code execution via a file upload vulnerability in the same version of Atutor. 3. Details XSS 1: Reflected XSS - Calendar CVSS: Medium 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N Description: The calendar_next parameter of the calendar is vulnerable to XSS. This issue has been fixed in ATutor 2.2.1-RC1. Proof of Concept: http://localhost/ATutor/mods/_standard/calendar/getlanguage.php?token=calendar_next<script>alert(1)<%2fscript>&pub=1 Code: /mods/_standard/calendar/getlanguage.php $token = $_GET['token']; echo _AT($token); XSS 2: Persistent XSS - Profile CVSS: Medium 5.0 AV:N/AC:L/Au:N/C:N/I:P/A:N Description: When saving profile information, < is filtered out. < on the other hand is not filtered, but converted to <, which leads to persistent XSS. A user account is needed, but registration is open by default. This issue has been fixed in ATutor 2.2.1. Proof of Concept: Visit: http://localhost/ATutor/users/profile.php In any field, enter <img src=no onerror=alert(1)> The input is for example echoed when visiting http://localhost/ATutor/users/ profile.php. This self-XSS may be exploited by force-logging in the victim. The input is not only echoed to the user themselves, but also in other places. For example, an attacker could send a private message to a victim. When the victim views the message, or visits their inbox, the injected code will be executed. XSS 3: Persistent XSS - Forum CVSS: Medium 5.0 AV:N/AC:L/Au:N/C:N/I:P/A:N Description: When creating a forum post, the Subject parameter is vulnerable to persistent XSS. A user account is needed, but registration is open by default. This issue has been fixed in ATutor 2.2.1. Proof of Concept: Visit a forum, eg here: http://localhost/ATutor/mods/_standard/forums/forum/view.php?fid=1&pid=1 Post a new message, as Subject, use: Re: test topic'"><img src=no onerror=alert(1)> In ATutor 2.2.1-RC1, < and > are encoded, preventing the proof of concept from working. But until version 2.2.1, it was still possible to exploit this issue either by using the JavaScript context the input is echoed into (onClick), or by adding a new attribute: adding new attributes: Re: ';" onmouseover="alert(1); var foo=' staying inside the existing JavaScript context: Re: test topic';alert(1);var foo=' XSS 4: Persistent self-XSS - Calendar CVSS: Low 2.6 AV:N/AC:H/Au:N/C:N/I:P/A:N Description: The event name of the calendar is vulnerable to persistent XSS. The calendar seems to be shown only to the user creating it, meaning the only way to exploit this issue would be to force-login the victim. A user account is needed, but registration is open by default. This issue has been fixed in ATutor 2.2.1-RC1. Proof of Concept: Visit: http://localhost/ATutor/mods/_standard/calendar/index_mystart.php Create event with name: '"><img src=no onerror=alert(1)> Visit event page: http://localhost/ATutor/mods/_standard/calendar/index_mystart.php XSS 5: Persistent XSS - Chat CVSS: Medium 5.0 AV:N/AC:L/Au:N/C:N/I:P/A:N Description: When viewing the chat history, chat messages are not properly HTML encoded, leading to persistent XSS. A user account is needed, but registration is open by default. This issue has been fixed in ATutor 2.2.1-RC1. Proof of Concept: 1. Visit Chat: http://localhost/ATutor/mods/_standard/chat/chat.php 2. Enter chat message: '"><img src=no onerror=alert(1)> 3. Visit chat history of that user: http://localhost/ATutor/mods/_standard/chat/filterHistory.php?filterChatID=[USERNAME] 4. Solution To mitigate this issue please upgrade at least to version 2.2.1: http://www.atutor.ca/atutor/download.php Please note that a newer version might already be available. 5. Report Timeline 11/17/2015 Informed Vendor about Issue 11/21/2015 Vendor requests more time 01/06/2016 Vendor releases new release candidate with partial fix 01/30/2016 Vendor releases complete fix 02/01/2016 Disclosed to public Blog Reference: https://blog.curesec.com/article/blog/Atutor-22-XSS-149.html -- blog: https://blog.curesec.com tweet: https://twitter.com/curesec Curesec GmbH Curesec Research Team Romain-Rolland-Str 14-24 13089 Berlin, Germany
