[FD] Simple ASC CMS v1.2 - (Guestbook) Persistent Vulnerability

Document Title: =============== Simple ASC CMS v1.2 - (Guestbook) Persistent Vulnerability References (Source): ==================== http://ift.tt/2q1q3gh 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://ift.tt/2rH0Y7k ) 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

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